RNA Viruses
Name That Viral Family! Envelope Yes RNA structure SS (NEGative) circular 3 segments Capsid symmetry Helical Medical importance California encephalitis Sand fly/Rift Valley fevers Crimean-Congo hemorrhagic fever Hantavirus--- hemorrhagic fever, pneumonia
Viral Family Bunyaviruses
Are Pandemics local or worldwide?
worldwide
Togaviruses
• ssRNA • Enveloped, icosahedral symmetry • Family Togaviridae • Genus alphavirus: Arboviruses • Genus rubivirus: Rubella
Name That Virus! -A flavivirus (also an arbovirus) --transmitted by Aedes mosquitoes. --virus has a monkey or human reservoir --Symptoms: high fever, black vomitus, and jaundice Hints: Flavi = yellow jaundice
Yellow Fever virus
KEY CONCEPTS POSitive strand RNA viruses
•Positive-strand RNA viruses: -have single-stranded RNA genomes of the same polarity or sense as mRNA .-The (+) strand RNA virus genome functions as mRNA, and the naked RNA is infectious. -All (+) RNA viruses encode an RNA-dependent RNA polymerase used in genome replication. Unlike other RNA viruses, (+) RNA viruses do not carry the polymerase as part of the virion structure. •Medically important (+) RNA viruses encompass six virus families (Picornaviridae, Caliciviridae, Astroviridae, Togaviridae, Flaviviridae, and Coronaviridae) and share similar properties.
What are the 3 C's of measles?
cough coryza conjunctivitis
Are Epidemics local or worldwide?
local
What are the etiologic agents of the "common cold"?
#1)Rhinoviruses #2)Coronaviruses (HCoV-229E)
Rabies virus
---Bullet shaped virus ---Negri bodies are characteristic cytoplasmic inclusions in neurons infected by ________ virus; commonly found in Purkinje cells of cerebellum ---Travels to the CNS by migrating in a retrograde fashion up the nerve axon ---Long incubation period (weeks to months before symptom onset) ---Progression of Disease: fever, malaise ----> agitation, photophobia, hydrophobia ---->paralysis, coma -----> death
What are the members of Retroviridae? Hints: (+) RNA, 2 identical segments Lipid envelope
-Human T lymphotropic virus types 1 and 2 -Human Immunodeficiency virus types 1 and 2
What are the members of Paramyxoviridae? Hints: (-) RNA Lipid envelop
-Parainfluenza virus -Respiratory syncytial virus -Newcastle disease virus -Mumps virus -Rubeola (measles) virus
What are some disease mechanisms of Human Coronaviruses?
-Virus infects epithelial cells of upper respiratory tract -Virus replicates best at 33-35C; therefore it prefers the URT -Reinfection occurs in the presence of serum antibodies -The glycoprotein "corona" helps this enveloped virus survive the GI tract -Severe acute respiratory syndrome infection is exacerbated by inflammatory responses
Disease mechanisms of Human Coronaviruses
-virus infects epithelial cells of upper respiratory tract --virus best replicates at 33-35C; therefore it prefers URT --Reinfection occurs in the presence of serum antibodies --The glycoprotein "corona" helps this enveloped virus survive the GI tract --Severe acute respiratory syndrome infection is exacerbated by inflammatory responses
A 24-year-old woman has had fever and a sore throat for the past week. Moderately severe pharyngitis and bilateral cervical lymphadenopathy are seen on physical examination. Which one of the following viruses is LEAST likely to cause this picture? A) Norovirus B) Adenovirus C) Coxsackie virus D) Epstein-Barr virus
A
What are the Segmented Viruses?
All are RNA viruses. They include: Bunyaviruses, Orthomyxoviruses (influenza viruses) Arenaviruses, Reoviruses BOAR
What does the Rabies structure look like?
Bullet-shaped virus
Each of the following statements concerning hepatitis C virus (HCV) and hepatitis D virus (HDV) is correct EXCEPT: A) HCV is an RNA virus that causes post-transfusion hepatitis. B) HDV is a defective virus that can replicate only in a cell that is also infected with hepatitis B virus. C) HDV is transmitted primarily by the fecal-oral route. D) People infected with HCV commonly become chronic carriers of HCV and are predisposed to hepatocellular carcinoma.
C
Mnemonic for POSitive-Sense RNA Virus Families: Calcivirus Hepevirus Picornavirus Flavivirus Togavirus Coronavirus Retrovirus
Call Pico and Flo To Come Rightaway
Influenza viruses Genetic Drift
Causes epidemics. Minor (antigenic drift) changes based on random mutation
Influenza viruses Genetic shift/antigenic shift
Causes pandemics. Reassortment of viral genome; segments undergo high-frequency recombination, such as when human flu A virus recombines with swine flu A virus.
_________________ is a family of viruses that causes the common cold, severe acute respiratory syndrome, Middle East respiratory syndrome, and COVID-19.
Coronavirus
What virus is the most likely etiological agent of the following Clinical summary? Herpangina: Vesicular lesions on the tongue and roof of the mouth of a 7-year-old patient accompany fever, sore throat, and pain on swallowing
Coxsackie A virus
This virus is responsible for nearly all cases of infantile respiratory bronchiolitis: A) parainfluenza virus B) metapneumo virus C) coxsackie A virus D) respiratory syncytial virus
D) respiratory syncytial virus RSV is the most common cause of severe lower respiratory tract disease in infants and young children. Persistence of immunity does not often occur so reinfection is common. [Mahon 2015, p712]
Name that Hepatitis Virus! Virus RNA picornavirus Transmission fecal-oral Carrier No Incubation Short (weeks) HCC Risk No Notes Asymptomatic (usually) Acute Alone (no carriers)
HAV
Name that Hepatitis Virus! Virus RNA Flavivirus Transmission primarily blood, IVDU, Post transfusion Carrier yes Incubation Long HCC Risk Yes; from chronic inflammation Notes Chronic, Cirrhosis, Carcinoma, Carrier Acute Alone (no carriers)
HCV
Name that Hepatitis Virus! Virus RNA delta virus Transmission Parenteral, sexual, maternal-fetal Carrier Yes Incubation Superinfection-- short Co-infection-- long HCC Risk Yes Notes Defective virus Dependent on HBV; superinfection--> poor prognosis
HDV
Major Human Coronavirus Proteins Proteins E1(matrix glycoprotein)
Location Envelope Functions Transmembrane protein
Name That Virus! --A paramyxovirus --Symptoms: Parotitis, Orchitis (inflammation of testes), and aseptic Meningitis --Can cause sterilitiy (especially after puberty) Hint(s): Makes your parotid glands and testes as big as POM-poms.
Mumps virus
What is the best specimen for diagnosis of Rhinovirus?
Nasal wash
Fill in the Blank: Under a magnification of 500X, this photomicrograph of a brain tissue specimen, extracted from an unknown source, revealed the presence of intracellular, magenta-colored inclusions known as _____________ bodies, in a case of rabies.
Negri
Name That Virus! -Nonenveloped RNA virus. -A picornavirus. -Cause of common cold; > 100 serologic types -Acid labile---destroyed by stomach acid; therefore does not infect the GI tract (unlike the other picornaviruses Rhino has a runny nose
Rhinovirus
ROTAvirus =
Right Out The Anus
Epidemiology: _____________ are largely transmitted via mosquitoes
Togaviruses
Shared properties of Picornaviruses, togaviruses, flaviviruses, calciviruses, and coronaviruses
(+) POSitive RNA genome resembles mRNA and is translated into a polyprotein, which is proteolyzed A (-) NEGative RNA template is used for replication Togaviruses, coronaviruses, and noroviruses have early and late genes
What are the members of Flaviviridae?
-Yellow fever virus -Dengue virus -St. Louis encephalitis virus -West Nile virus -Zika virus -Hepatitis C virus -Hepatitis G virus
How do you treat the common cold?
-nasal vasoconstrictors -inhale hot humid air and steam from hot chicken soup
Why is there no vaccine for the common cold?(Rhinovirus)
-numerous serotypes -immunity wanes about 18 months after infection -immunity is type-specific and correlates best with local production of secretory IgA
Rhinovirus Transmission
-only need 1 virion -respiratory aerosols -fomites -hands
Pathogenesis of Rhinovirus
-uses ICAM-1 receptor of immunoglobulin superfamily of proteins -predilection for cooler environment of nasal mucosa -unable to replicate in GI tract -labile to acidic pH -grows best at 33C -enters through mouth,nose, eyes and initiates infection of URT including throat -infected cells release bradykinin and histamine causing a "runny nose" -gradual antigenic drift
Each of the following statements concerning the prevention and treatment of influenza is correct EXCEPT: A)The inactivated influenza vaccine contains H1N1 virus, whereas the live, attenuated influenza vaccine contains H3N2 virus. B) The vaccine is recommended to be given each year because the antigenicity of the virus drifts. C) Oseltamivir (Tamiflu) is effective against both influenza A and influenza B viruses. D) The main antigen in the vaccine that induces protective antibody is the hemagglutinin.
A
Regarding poliovirus and the disease poliomyelitis, which one of the following is most accurate? A) Poliovirus is transmitted primarily by the fecal-oral route. B) New antigenic variants arise by coinfection with animal strains of poliovirus. C) Paralytic poliomyelitis is the most common manifestation of poliovirus infection. D) Poliovirus has single-stranded RNA as its genome and a polymerase in the virion that synthesizes its mRNA. E) The current vaccine recommendation is to give the live, attenuated vaccine for the first three immunizations to prevent the child from acting as a reservoir, followed by boosters using the killed vaccine.
A
The most common causes of viral pneumonia in adults are: A) Influenza and adenovirus B) Hepatitis A and B viruses C) Coxsackie A and B viruses D) Herpes simplex and CMV
A) Influenza and adenovirus influenza and adenoviruses are the main causes of respiratory infections, including the common cold, tracheobronchitis, and pneumonia. Adenoviruses also cause conjunctivitis, keratitis, cystitis, and gastroenteritis.
You are working as a public health practitioner in a county of 100,000 individuals. You are asked to investigate an outbreak of a febrile illness accompanied by rash at a small, private preschool. The initial case of illness occurred in a 28-year-old teacher who had recently returned from visiting her family in India. She was born in India and moved to the United States at the age of 4 years. She received her usual childhood immunizations at that time. Her illness began with fever and fatigue about 14 days ago. She stayed home from work until the fever subsided 6 days ago. She had onset of rash that is erythematous and macular. It began on the face, neck, and near the hairline but has become generalized and confluent on the trunk. When examining her oral mucosa, the lesion shown in Figure IV-215 is seen. There are now four children in the preschool exhibiting a high fever, and two have developed a similar rash. Review of medical records at this school shows nonvaccination rates of 25%. Which of the following vaccine-preventable illnesses is most likely? A) Measles B) Mumps C) Poliovirus D) Rubella E) Varicella
A) Measles Measles remains a common illness worldwide and continues to pose a significant health threat in the United States among individuals who are unvaccinated. Prior to the availability of the measles vaccine, an estimated 3-5 million individuals died of measles and its complications yearly. However, since the introduction of the measles vaccine in the 1960s, the number of cases of measles worldwide has declined. By 2008, the estimated number of deaths due to measles had declined to <200,000 yearly, but measles remains a common cause of death among children under the age of 5 in developing countries. Areas that continue to have a high number of measles cases include India, Pakistan, China, and Southeast Asia. Some areas of Africa also have greater numbers of measles cases. Measles is caused by a single-stranded RNA virus that is a member of the Morbillivirus genus. It is one of the most highly contagious directly transmitted pathogens. Outbreaks can occur in populations even if <10% of the individuals are susceptible. Susceptible household contacts have attack rates of >90%. Frequent settings for outbreaks include schools and healthcare settings. The virus is transmitted by respiratory droplets in short distances or, less commonly, by small-particle aerosols that remain suspended in the air for long periods. After exposure, there is a 10-day incubation period. During this time, the virus is replicating locally in the respiratory epithelium with development of a secondary viremia at 5-7 days. Prior to symptom onset and during viral replication, affected individuals can shed high numbers of viral particles, fostering further spread of disease. After the incubation period, initial symptoms include fever, malaise, cough, conjunctivitis, and coryza. Koplik spots (Figure IV-215) are diagnostic of measles. The bluish white dots appear initially on the buccal mucosa and are surrounded by erythema. They precede the onset of rash typically by 2 days. The rash of measles is erythematous and macular. It begins most commonly behind the ears and along the neck and hairline. It progresses to involve the face, trunk, and arms, where it may become confluent. Petechiae may be present. The rash fades in the same order of progression, and desquamation of the skin may occur. Deaths due to measles occur related to respiratory complications including bacterial pneumonia as well as encephalitis. In developed countries, the case-fatality rate of measles in children is <1 in 1000, but death rates as high as 20%-30% can occur in refugee camps. Vaccination is highly effective in measles prevention. Infants who have been vaccinated develop effective immunity by the age of 9 months in 85% and by the age of 12 months in 95%. Rates of secondary vaccine failure are low, typically around 5% or less, even 10-15 years after vaccination. Due to the misconception that measles vaccination is associated with the development of autism, there has been a rise in nonvaccination in the United States, with periodic outbreaks as a result. In this setting, the disease is most often introduced by an affected individual who recently traveled to an area where measles remains common. (Chap. 229)
A 40-year-old female experienced a respiratory infection after returning home from a visit to her homeland of China. A rapid onset of pneumonia in the lower respiratory area prompted the physician to place her in isolation. She was diagnosed presumptively with severe acute respiratory syndrome (SARS) and placed on a respirator. What type of testing should be done next to diagnose this disease? A) Molecular technique and cell culture B) Latex agglutination test C) Blood culture D) Complement fixation
A) Molecular technique and cell culture SARS virus was discovered in China in 2003. The virus belongs to the common cold group of coronaviruses, and is easily transmitted to healthcare workers having close contact with infected patients. It is the cause of the severe lower respiratory infection that can be fatal. Laboratory confirmation may be done by PCR testing is available commercially, cell culture, EIA, or IFA. Typically, PCR is used on two different specimen types with the same specimen type submitted at least two days apart. If both tests are positive, the infection is confirmed.
Which virus is the most common etiological agent of viral respiratory diseases in infants and children? A) Respiratory syncytial virus (RSV) B) Measles virus C) Coxsackie A virus D) Coxsackie B virus
A) Respiratory syncytial virus (RSV) RSV is the cause of croup, bronchitis, bronchiolitis, and interstitial pneumonia. Children under one year old who are hospitalized are the most susceptible group.
A six month old male infant was hospitalized with a respiratory infection. He was diagnosed with apnea and bronchiolitis. Further testing revealed congenital heart disease. Bacterial cultures were negative for Streptococcus pneumoniae and Haemophilus influenzae. What further testing should be done? A) Respiratory syncytial virus (RSV) B) Rotavirus C) Norwalk virus D) HIV
A) Respiratory syncytial virus (RSV) Respiratory syncytial virus is spread by large particle droplets such as dust and is one of the most common causes of hospitalization for respiratory illness of infants less than one-year-old. RSV causes bronchiolitis, pneumonia, and croup in infants and respiratory upper respiratory illness in children. It is also been found to cause nosocomial infection in nursing homes. Diagnosis is made by EIA, fluorescent antibody (FA) staining, and cell culture.
A 48-year-old woman comes to the clinic because of increasing breathlessness. She returned from a trip to Hong Kong, China 2 weeks ago and reports fevers, muscle aches, headache and a dry cough for the last week. Over the last 2 days she had noticed increasingly severe breathlessness. Past medical history is noncontributory. CXR shows bilateral patchy infiltrates. Laboratory studies show leukopenia. Which of the following is the most likely cause of this patient's symptoms? A) SARS-CoV B) Zika virus C) Dengue virus D) Legionella pneumophila E) Plasmodium species
A) SARS-CoV Consider SARS in a patient presenting with symptoms and signs of atypical pneumonia starting within 10 days of travel to high risk areas. characterized by up to a week of high fever and non-specific viral symptoms followed by development of a dry cough and dyspnea. The incubation period is 2-10 days. CXR shows bilateral patchy infiltrates consistent with atypical pneumonia laboratory studies show leukopenia
Which technique is used for the confirmation of infection with human immunodeficiency virus (HIV-1)? A) Western blot (immunblot) assay B) Enzyme-linked immunosorbent assay (ELISA) C) Complement fixation D) p24 antigen testing
A) Western blot (immunblot) assay the Western blot essay is most often used to confirm the positive serological test of antibodies to HIV. The samples confirmed positive antibodies are demonstrated against two of the three major regions (env, pol, and gag). However, because the Western blot detects antibodies it may miss people in the window phase of infection, is not confirmatory for neonatal infections due to the presence of maternal antibodies, and has a long turnaround time resulting in a loss of contact with the patient. For these reasons, the CDC is evaluating a new approach using a simultaneous test for antibodies to both HIV-1 and HIV-2 and P 24 antigen to screen for infection. Positives will be tested by separate immunoassays to identify whether the infection is HIV-1 or HIV-2. Samples testing negative for both of these would be tested by nucleic acid amplification method such as PCR for viral RNA.
Which of the following statements regarding antigenic shift or drift in influenza is correct? A) antigenic drift is due to point mutations in the H&N genes B) antigenic drift is responsible for pandemics of influenza C) antigenic shift is responsible for seasonable epidemics of influenza D) local annual outbreaks of influenza are often due to antigenic shift
A) antigenic drift is due to point mutations in the H&N genes Drift refers to minor changes that occur during point mutations. Drift is primarily responsible for the annual outbreaks and epidemics of influenza. Shift refers to a more major change due to recombination between different viral subtypes and is most often the cause of the periodic pandemic infections. It is due to both antigenic drift and shift that lifelong immunity to influenza cannot CURRENTLY be achieved. [Mahon 2015, p709; QCClinPath 3e 2014, p90]
Which test is the primary screening test for HIV? A) serum enzyme linked immunosorbent assay B) western blot C) quantitative HIV RNA D) CD4 count
A) serum enzyme linked immunosorbent assay The extremely high sensitivity of the serum ELISA test makes it the screening test of choice. There can be a window period between the infection and seroconversion, usually 6-8 weeks, leading to possible false-negative results. The confirmation of a positive result is usually done with Western blot, that detects antibodies to specific antigens such as p24, p31, gp41, and gp120/160 are positive. [Mahon 2015, p715]
A 12-year-old girl is seen by her pediatrician with symptoms of vomiting, diarrhea, nausea, stomach cramps, chills, and fever. Symptoms began 1 day after attending a school dinner and pool party at a local country club. What is the most likely diagnosis?
Acute Gastroenteritis Etiology and Epidemiology: Noroviruses belong to the calicivirus family and are the most common cause of acute gastroenteritis in older children and adults in the United States. Noroviruses are transmitted by the fecal-oral route. Norovirus outbreaks are associated with the ingestion of contaminated food or water, direct person-to-person contact, and contact with contaminated environmental surfaces. Clinical Manifestations: Acute gastroenteritis is characterized by acute onset of vomiting, diarrhea, nausea, abdominal cramps, and fever. Norovirus incubation period is short, usually 24-48 hours (range, 12-72 hours), and the onset of symptoms is typically very abrupt. The duration of illness is usually 48-72 hours with rapid recovery. Vomiting is a prominent symptom. Diarrhea is generally watery without blood or mucus. Pathogenesis: Norovirus infects the small bowel and directly damages enterocytes. Norovirus-induced pathology leads to transient malabsorption of water and nutrients and reduced gastric motility, culminating in vomiting and diarrhea. Laboratory DiagnosisNorovirus is detected in clinical or environmental samples by reverse transcriptase-PCR. Treatment and Prevention: Currently, there is no specific treatment or vaccine for norovirus infection. Supportive care is the mainstay of treatment. Handwashing and use of surface disinfectants are effective means of prevention.
A 14-year-old girl is seen in a pediatric practice with a sudden onset of fever (39.4°C), headache, stiff neck, and photophobia. She returned home last week from summer vacation at a recreational vehicle campsite that featured a campground pool. What is the most likely diagnosis?
Aseptic Meningitis Etiology and Epidemiology: Nonpolio enteroviruses (coxsackieviruses and echoviruses) are a common cause of aseptic meningitis. Coxsackie and echoviruses are transmitted by the fecal-oral route and direct contact with infected secretions; less commonly by respiratory droplets. Coxsackie and echovirus infections are most common in the summer and fall months in temperate climates. Each virus has numerous serotypes. Clinical Manifestations: Aseptic meningitis is characterized by acute onset of fever, headache, stiff neck, and photophobia. Most patients recover in about a week with no CNS sequelae. Other disease syndromes associated with coxsackieviruses and echoviruses include herpangina (coxsackie A and echovirus), hand-foot-and-mouth disease (coxsackie A), pleurodynia and myalgia (coxsackie B), acute hemorrhagic conjunctivitis (coxsackie A), and pericarditis and myocarditis (coxsackie B). Additionally, enterovirus D68 (EV-D68), while known for many decades, has recently been associated with clusters of cases of upper and lower respiratory infections in young children with CNS manifestations of acute motor neuron disease similar to poliomyelitis. Pathogenesis: Coxsackievirus and echovirus pathogenesis is similar to that of poliovirus but differs by commonly infecting the meninges rather than the motor neurons. Virus directly damages and kills target cells. Clearance of the virus is antibody-mediated. Laboratory Diagnosis: Coxsackieviruses, echoviruses, and other enteroviruses are detected and differentiated by PCR. Treatment and Prevention: There is no treatment or vaccine for coxsackie, echovirus, or other enterovirus infection. Control measures include frequent handwashing and avoidance of sharing of towels and bedding with persons with conjunctivitis.
Albert is a 20-year-old male presenting with sore throat, cough, muscle aches, and a high fever that persisted for several days. The symptoms develop shortly after he returned from a visit to China during which he visited a poultry farm. His symptoms are typical of the seasonal flu, but he reports that he was vaccinated before his trip to China, raising the suspicion that he has acquired avian flu, which is more life-threatening. Question: How could infection of humans with avian flu lead to an epidemic?
Avian influenza (H5N1) infections have been reported in Asia, Africa, and Europe. It can be transmitted by direct contact with infected poultry, although human to human infection is rare. The possibility exists that during human infection, the virus could undergo alterations via genetic shift, recombination between different strains of virus. The new virus, to which there has not been extensive human exposure, could cause a worldwide outbreak of the disease.
Regarding "slow viruses" and their diseases, which one of the following is the most accurate? A)The viruses that cause slow diseases, such as progressive multifocal leukoencephalopathy (PML), have a slow rate of replication that accounts for the long latent period and slow progression of the disease. B) PML is caused by a virus that causes widespread inapparent infections early in life but causes the disease PML primarily in people with reduced cell-mediated immunity. C) Creutzfeldt-Jakob disease (CJD) is caused by CJ virus, a retrovirus that integrates a DNA copy of its genome into the DNA of brain neurons. D) CJD occurs primarily in immunocompromised people, but infection with the virus that causes CJD is common, as evidenced by the presence of antibodies.
B
Which of the following groups contains the SARS virus? A) Calicivirus B) Coronavirus C) Flavivirus D) Filovirus
B) Coronavirus The severe acute respiratory syndrome (SARS) virus arose as a previously unrecognized organism causing serious respiratory tract infections. This virus has been shown to be part of the coronavirus group.
Which virus belonging to the Reoviridae group causes gastroenteritis in infants and young children but an asymptomatic infection in adults? A) Coxsackie B virus B) Rotavirus C) Respiratory syncytial virus D) Rhabdovirus
B) Rotavirus Rotaviruses have been implicated in both nosocomial infections and epidemic gastroenteritis. Children 3-24 months old are most commonly affected. Diarrhea begins after an incubation period of three days, last for 2-10 days, and is associated with vomiting and dehydration. In Immunosuppressed children, rotavirus causes a chronic infection.
Which of the following organisms is the causative agent of hand, foot, and mouth disease? A) Adenovirus B) coxsackie A C) coxsackie B D) human herpes virus 6
B) coxsackie A Coxsackie A & B are frequently confused for each other in terms of the diseases that they cause. Coxsackie A causes hand, foot, and mouth disease, so named for the most common location of the lesions. Coxsackie B is responsible for the majority of cases of viral myocarditis. [Mahon 2015, p823]
The organs of a 65-year-old male were donated soon after a fatal auto accident. Three recipients of his corneas and kidneys died with weeks after receiving his organs. Which of the following viruses most likely caused the death of these recipients? A. HIV B. Rabies C. Norwalk-like D. Rotavirus
B. Rabies Transmission of rabies (rhabdovirus) occurs primarily from the bite of a rabid animal, but in 20% of human rabies cases there is no known exposure to rabid animals. Donor tissues are not routinely tested for rabies. Diagnosis approved is performed by fluorescent antibody staining of the infected tissues, and electron microscopy that shows the presence of blood shaped virus particles
Regarding rabies virus and the disease rabies, which one of the following statements is most accurate? A)Finding intranuclear inclusion bodies within macrophages is presumptive evidence of rabies virus infection. B) Lamivudine is used to treat rabies because it inhibits the RNA-dependent DNA polymerase in the virion. C) In the United States, skunks and bats are more likely to transmit rabies virus to people than are dogs and cats. D) The incubation period of the disease is usually 2 to 4 days, leading to the rapid progression of the encephalitis and death. E) After the animal bite, rabies virus enters the bloodstream, replicates in internal organs such as the liver, and then reaches the central nervous system during the secondary viremia.
C
Which of the following groups of virus is best described as: ssRNA, enveloped, Pleomorphic/spherical capsid Large club-shaped spikes on surface gives "corona" effect Causes approximately 15% of coldlike illness A) Influenza A B) Influenza B C) Coronaviruses D) Pneumovirus
C) Coronaviruses This is the description of the coronavirus group.
In a person vaccinated against hepatitis B virus several years prior, which serological marker would be expected? A) HBsAg B) HBeAg C) anti-HBs D) anti-HBc
C) anti-HBs Anti-HBs in serum indicates convalescence or immune status. All of the other choices, with perhaps the early appearance post vaccination of HBsAg, should not be seen in a vaccinated person. HBeAg is present during active viral replication. Anti-HBc shows early in the course of disease and shows an acute infection. [Mahon 2015, p719; QCClinPath 3e 2014, p89]
A 13-year-old boy was admitted to the hospital with a diagnosis of viral encephalitis. History revealed that the boy harbored wild raccoons from nearby woods. What is the best method to determine if the boy has contracted rabies? A) remove the brain stems from all directions and examine for cytopathic effects B) request immunofluorescent test for antibody on the saliva from all of the raccoons C) request immunofluorescent test for antigen in cutaneous nerves obtained by nuchal biopsy of the patient D) isolate the virus from the saliva of the animals in the patient
C) request immunofluorescent test for antigen in cutaneous nerves obtained by nuchal biopsy of the patient Using direct immunofluorescence, rabies antigen can be detected in the cutaneous nerves surrounding the hair follicles of the posterior region of the neck (nuchal biopsy) and in epithelial cells obtained by a corneal impression. Antibodies to rabies can be detected in the serum and CSF of infected persons within 8-10 days of illness; however, infection usually occurs several months before the onset of symptoms. Isolation virus from the saliva of the patient may be accomplished by mouse inoculation or by inoculation of susceptible cell culture lines with subsequent detection by immunofluorescent antibodies.
A 40-year-old female returns from a 2-week trip to India where she traveled to various urban regions of the country for sightseeing. Approximately 3 days after returning she develops headache, malaise, and fevers (39.0-39.8°C). Approximately 2 days later, she also develops a rash on her face, trunk, and extremities, and experiences polyarthralgias involving multiple joints, especially of the hands, wrists, ankles, and knees. She presents to her primary care physician, and upon examination, she is found to have a fever of 39.2°C, tenderness and swelling of multiple joints, and a diffuse maculopapular rash located on her face, trunk, and extremities. Blood smears are negative for malaria. HIV testing is negative. Blood cultures are sent and are pending. Clinical laboratory findings reveal lymphopenia, thrombocytopenia, and transaminitis. What is the most likely diagnosis?
Chikungunya Etiology and Epidemiology: Chikungunya virus is an alphavirus and a member of the Togaviridae family. The name "chikungunya" is derived from the Makonde language in Africa meaning "that which bends up" in reference to the stooped posture of the patient suffering from incapacitating arthralgias from the infection. Chikungunya virus is transmitted by the bite of infected mosquitoes, and less commonly, by maternal-fetal transmission, blood product transfusion, or organ transplantation. It is endemic in certain parts of West Africa, and outbreaks have occurred in Africa, Asia, Europe, islands in the Indian and Pacific Oceans, the Caribbean islands, and the Americas. A large outbreak occurred on Réunion island in 2005-2006 that affected over 260,000 people, over a third of the island's population. Clinical Manifestations: Chikungunya virus infection usually causes a self-limited illness that lasts about 7-10 days. The incubation period is typically 3-7 days, with a range of 1-14 days. Clinical manifestations typically include fever for 3-5 days, malaise, polyarthralgias, and rash. Polyarthralgias are a predominant feature and typically inolve smaller joints of the fingers, hands, wrists, and ankles as well as larger joints, such as shoulders and knees. Occurrence of a patchy or diffuse macular or maculopapular rash on the face, trunk, and extremities is common. Severe complications can include respiratory failure, cardiovascular decompensation, hemorrhage, renal failure, and neurological manifestations such as meningoencephalitis or Guillain-Barré syndrome. In rare cases, relapse or persistence of symptoms may occur months after the initial infection. Laboratory abnormalities can include lymphopenia, thrombocytopenia, transaminitis, and elevated creatinine. Pathogenesis: Chikungunya virus enters host cells by receptor-mediated endocytosis in clathrin-coated vesicles. The low pH of the endosome causes fusion of viral and host membranes, thus releasing the viral nucleocapsid into the host cell cytoplasm. Translation of the viral genome results in formation of a replication complex, which replicates and produces full length minus strand genome. Nonstructural viral proteins act as the plus strand replicase to produce plus strand RNA that encodes the protein precursors of the viral structural proteins. The structural proteins are processed in the Golgi complex and are then transported to the plasma membrane. The viral RNA is packed into nucleocapsids, and the mature virions bud out of the plasma membrane. Laboratory Diagnosis: Chikungunya virus is detected by reverse transcriptase PCR assay or by serology. Treatment and Prevention: Supportive therapy is the mainstay of care since there is no treatment for Chikungunya virus infection. Mosquito vector control, protective clothing, and insect repellant containing DEET are key preventive measures.
An 18-year-old college student is seen in the university health clinic with complaints of sneezing, nasal discharge, nasal congestion, headache, sore throat, and cough for 3 days. Physical examination revealed an afebrile, normal-appearing male patient. What is the most likely diagnosis?
Common Cold Etiology and Epidemiology: Rhinoviruses are the most frequent cause of the common cold. Rhinoviruses are transmitted by hand-to-nose or hand-to-eye contact with contaminated respiratory secretions or respiratory droplets. Rhinoviruses are distributed worldwide; more than 100 rhinovirus serotypes are known. Clinical Manifestations: The common cold is characterized by an incubation period of 2-3 days followed by rhinorrhea, nasal congestion, sneezing, headache, mild pharyngitis, and cough, with little or no fever. Symptoms resolve after a week generally without complications. Pathogenesis: Rhinoviruses gain entry to cells in the nasopharynx by attachment to the intercellular cell adhesion molecule-1 (ICAM-1) receptor. Replication is localized to nasal epithelial cells and virus is shed in respiratory secretions. The virus causes minimal pathology to respiratory epithelial cells. The major pathogenesis of rhinovirus infections is associated with chemical mediators of inflammation (bradykinin, prostaglandins) that cause vasodilation, mucus secretion, and stimulation of the sneeze and cough reflexes. Laboratory Diagnosis: The common cold is a clinical diagnosis. It is often self-diagnosed by the patient who may or may not seek medical evaluation, depending on the severity of illness. Treatment and Prevention: There is no treatment and no vaccine to prevent rhinovirus colds. Handwashing is an effective method of prevention.
A pregnant 16-year-old female living in Haiti was brought to the hospital in labor where she subsequently gave birth to a baby girl. The mother had a flu-like illness with a low-grade fever, maculopapular rash, and lymphadenopathy during the second month of pregnancy. On examination, the baby had a blueberry muffin-like rash and cataracts. What is the most likely diagnosis?
Congenital Rubella Etiology and Epidemiology: Rubella virus, a member of the togavirus family, is the cause of congenital rubella syndrome. Rubella virus is transmitted postnatally by respiratory droplets of infected individuals. Congenital infections occur by transplacental transmission from infected mother to the fetus. Rubella virus is recognized as one of the most potent infectious teratogenic agents. Risk of congenital rubella syndrome is greatest during the first trimester of pregnancy but can occur throughout pregnancy. Rubella outbreaks in the United States are rare but occur in unvaccinated or undervaccinated populations in the United States or in countries where rubella vaccination is not routine. Rubella remains endemic in developing countries. Clinical Manifestations: Rubella virus causes a mild illness in children and adults characterized by an incubation period of 14-21 days followed by a generalized maculopapular rash, low-grade fever, and lymphadenopathy. Common complications of postnatal rubella are arthritis and arthralgia, most frequently in adults. Rubella virus infection of women in the first trimester of pregnancy causes congenital rubella syndrome in the child, which is characterized by cataracts, cardiac abnormalities, deafness, and mental retardation. Pathogenesis: In postnatal infections, rubella virus enters via the respiratory tract, spreads to local lymph nodes, then spreads to the spleen and regional lymph nodes and disseminates by viremia to the skin, kidneys, joints, and respiratory tract. In congenital rubella, the virus infects the placenta and spreads to the fetus with multiple organ involvement and teratogenic effects. Antibody response limits viral spread, but cell-mediated immunity is required to resolve infection. Laboratory Diagnosis: Rubella virus-specific IgM and IgG antibody detection is the most common diagnostic test for rubella virus infection. Treatment and Prevention: There is no specific treatment for rubella virus infection. Live, attenuated rubella virus vaccine is highly effective in preventing rubella. The vaccine is usually given as a combined measles, mumps, rubella (MMR) vaccine.
Name that Virus! -Causes Pleurodynia (Bornholm disease) -aka "Devil's grip" -An acute illness in which patients have a sudden onset of fever and unilateral low thoracic, pleuritic chest pain that may be excruciating -Abdominal pain and emesis can occur extremely tender muscles on the involved side -Lasts an average of 4 days
Coxsackie B (B for Body) virus
What virus is the most likely etiological agent of the following Clinical summary? Pleurodynia: A 13-year-old boy has fever and severe chest pain with headache, fatigue, and aching muscles lasting for 4 days
Coxsackie B (B for Body) virus
Each of the following statements concerning the prevention of viral respiratory tract disease is correct EXCEPT: A) To prevent disease caused by adenoviruses, a live enteric-coated vaccine that causes asymptomatic enteric infection is used in the military. B) To prevent disease caused by influenza A virus, an inactivated vaccine is available for the civilian population. C) There is no vaccine available against respiratory syncytial virus. D)To prevent disease caused by rhinoviruses, a vaccine containing purified capsid proteins is used.
D
A clinical test used for the detection and identification of viral infections other than culture is: A) Hemagglutination B) Hemadsorption C) Viral antigen detection D) All of these options
D) All of these options In addition to serological tests for antibodies against the virus and DNA probes that identify viral DNA or RNA, the methods above aid in the rapid diagnosis of several viruses. Various species of animal RBCs are used for identification of viruses that contain receptors that included the RBCs. Some influenza a and parainfluenza irises may be detected only by hemagglutination or hemadsorption. Testing for viral antigen and culture is used for detection of RSP, CMB, and varicella zoster.
A 65-year-old woman was admitted to the hospital with acute respiratory distress, fever, myalgia, and headache. Influenza A or B was suspected after ruling out bacterial pneumonia. Which of the following methods could be used to confirm influenza infection? A) Influenza virus culture in Madin-Darby canine kidney B) Hemagglutination-inhibition test for antibodies in the patient's serum C) Direct examination of nasal epithelium for virus using fluorescent antibody stain D) All of these options
D) All of these options Influenza virus types A, B, and C may be grown and isolated in embryo needed in eggs or cell cultures using Madin-Darby canine kidney (MDCK), rhesus monkey, or cynomolgus monkey kidney cells. Cell culture using MDC care cells is the most rapid technique, permitting identification within 1-3 days. The hemagglutination inhibition test can be used to tighter antibody to influenza virus and to distinguish virus subtypes, a specific antiserum is available. Direct fluorescent and enzyme immunoassays using monoclonal antibodies to nucleoprotein antigens in infected nasal epithelium are used for rapid diagnosis of both influenza A and influenza B infections.
A 25-year-old male patient was diagnosed with HIV-1 by enzyme immunoassay, testing positive twice, the diagnosis was confirmed by Western blot testing. Which laboratory tests should be performed prior to initiating antiviral therapy? A) Quantitative plasma virus concentration (viral load testing) B) Quantitation of CD4 lymphocytes C) Phenotype/genotype resistance testing D) All of these options
D) All of these options The decision to initiate antiviral therapy is based upon the presence or absence of symptoms, CD4 lymphocyte count, and the viral load. For example, treatment is usually withheld from patients with CD4 counts > 350/uL and viral load < 55,000/mL and is instituted in asymptomatic patients at the CD4 count is less than 200 per microliter regardless of viral load. Treatment failure within the first year with three drug regimens is 35-45%, and drug resistance testing (genotype and/or phenotype testing) is recommended to identify drug resistant strains prior to initiating treatment.
The most common viral syndrome of pericarditis, myocarditis, and pleurodynia (pain upon breathing) is caused by: A) Herpes simplex virus B) respiratory syncytial virus C) Epstein-Barr virus D) Coxsackie B virus
D) Coxsackie B virus Coxsackie A virus, Coxsackie B virus, and the echo viruses are most commonly implicated in myocarditis and other syndromes, including acute cerebellar ataxia and hepatitis. Like poliovirus, infections are more common in the summer and fall and gain entry through the gastrointestinal tract.
A three-year-old female was admitted to the hospital following a two day visit with relatives over the Christmas holidays. Vomiting and diarrhea left the child severely dehydrated. No other members of the family were affected. All bacterial cultures proved negative. A stool sample should be tested for which virus? A) CMV B) EBV C) Hepatitis D D) Rotavirus
D) Rotavirus Rotavirus is one of the most common causes of gastroenteritis in infants and young children (six months to two years old).-Like viruses. Vomiting and diarrhea are also common symptoms of Norwalk virus infections, but the prevalence of rotavirus during the winter months and the lack of illness and other family members make our rotavirus a more likely cause. Commercial availability of immunoassays for rotavirus makes its diagnosis easier to establish and rule out that infection with Norwalk
Which of the following is the most common cause of pediatric viral gastroenteritis? A) adenovirus, serotypes 40 and 41 B) Norwalk virus C) coronavirus D) rotavirus
D) rotavirus Rotavirus is the most common cause of viral gastroenteritis in infants and children. It causes >600,000 deaths annually. Coronavirus causes cold-like infections in adults and a small percentage of pediatric diarrhea cases. Adenovirus is mostly asymptomatic, causing a small percentage of pneumonia and gastroenteritis in children. Norwalk virus is the most common cause of adult viral gastroenteritis and is often responsible for the diarrheal outbreaks on cruise ships, resorts, or nursing homes. [Mahon 2015, p696,704,706,841]
A 17-year-old female presents to her health care provider with symptoms of sore throat, cervical lymphadenopathy, fever, fatigue, and myalgias. Which of the following should be excluded from her differential diagnosis? A) group A strep pharyngitis B) infectious mononucleosis C) human immunodeficiency virus D) rotavirus
D) rotavirus Rotavirus, while detected by antigen testing, is a gastrointestinal disease and is not indicated by the reported symptoms. [Stevens 2017, p425]
A three-year-old girl presents to the emergency department with fever, hoarseness, a "seal bark-like" cough, and inspiratory stridor. Her father states that she has had a cold for the past few days, with runny nose, nasal congestion, sore throat, and cough. He is now concerned because her cough has become loud, harsh, and brassy. Which of the following is the most likely cause of her ailment? A) fungus B) gram-negative bacteria C) gram-positive bacteria D) parasite E) virus
E) virus This is a classic case of acute laryngeotracheobronchitis (croup), and acute inflammation of the larynx, trachea, and epiglottis. The most common cause of croup is a viral (parainfluenza virus type I) infection. (BRS Pathology 5th edition, p223)
Poliomyelitis (Polio)
Etiology and Epidemiology: Poliomyelitis is caused by poliovirus. Poliovirus is transmitted by the fecal-oral route. Humans are the only natural hosts. Clinical Manifestations : Most (90%-95%) poliovirus infections are asymptomatic. Abortive poliomyelitis is the most common clinical form and is characterized by a flu-like illness, with fever, headache, sore throat, and nausea followed by spontaneous recovery without CNS sequelae. A minority (∼1%) of poliovirus infections result in either nonparalytic or paralytic poliomyelitis. Nonparalytic poliomyelitis is characterized by symptoms of aseptic meningitis with fever, headache, and stiff neck followed by spontaneous recovery. Paralytic poliomyelitis is characterized by asymmetric flaccid paralysis, most often affecting the legs. A post-polio syndrome is observed in about 25% of persons who survive paralytic poliomyelitis. The syndrome appears many years after full or partial recovery from acute polio infection and is characterized by constitutional, neurological, and musculoskeletal symptoms such as generalized fatigue, muscle or joint pain, and progressive muscle weakness with or without atrophy. Pathogenesis: Poliovirus initiates infection in the pharynx and gastrointestinal tract after ingestion, spreads to the draining lymph nodes, and then reaches the CNS by viremic spread. CNS invasion results in direct killing of motor neurons located in the anterior horn of the spinal cord, with subsequent paralysis. Clearance of poliovirus and recovery from infection are primarily due to IgA and IgG antibody responses Laboratory Diagnosis: Poliovirus can be detected in cell culture and identified with poliovirus-specific antibody. The gold standard method for diagnosis is reverse-transcriptase (RT) PCR amplification of polio virus RNA from cerebrospinal fluid. RT-PCR is also used to discriminate between poliovirus and other enteroviruses. Treatment and Prevention: There is no treatment for poliomyelitis. Polio can be prevented by either a live, attenuated (Sabin) or killed (Salk) vaccine. Killed polio vaccine is recommended in the United States because of rare cases of live vaccine-associated paralytic polio.
Name that Hepatitis Virus! Virus RNA hepevirus Transmission fecal-oral, especially with waterborne epidemics Carrier No Incubation Short HCC Risk No Notes High Mortality in pregnant Women; Enteric, Expectant mothers, Epidemic
HEV
A 25-year-old man is seen in an outpatient clinic with a chief complaint of fatigue, nausea, and vomiting for the past several days. He has had noticed that morning that his urine was dark yellow. On physical examination, the patient is found to have a low-grade fever, jaundice, and mild abdominal pain. He denies intravenous drug use and having unprotected sex or multiple sexual partners. He attended a 5-day outdoor rock concert in North Carolina 3 weeks earlier. He is a cook at the local university dining hall. What is the most likely diagnosis?
Hepatitis A Etiology and Epidemiology: Hepatitis A is caused by the picornavirus, hepatitis A virus (HAV). HAV is transmitted by the fecal-oral route. Epidemics of HAV are usually due to food- or water-borne infections associated with poor sanitary conditions and personal hygiene. Clinical Manifestations: Hepatitis A is characterized by an incubation period ranging from 15 to 50 days followed by the onset of fever, anorexia, nausea, vomiting, jaundice, and dark urine due to bilirubinuria. The duration of illness varies but is usually self-limiting with recovery in 3-4 weeks. Fulminant hepatitis leading to total liver failure and death is a rare complication. Pathogenesis: Ingested HAV initially infects cells in the oropharynx and gastrointestinal tract, spreads to the liver by viremia, and infects hepatocytes without producing marked cytopathology. Hepatic cell injury is mediated by immune attack by cytotoxic T cells. Virus from infected liver cells is shed into the intestine and excreted in the feces. HAV does not establish a chronic infection or carrier state. Serum IgG is important in recovery from infection and in long-term protection. Laboratory Diagnosis: HAV is detected by HAV-specific IgM antibody, which peaks during the acute or early convalescent stage of illness and remains detectable for approximately 3-6 months. Treatment and Prevention: There is no treatment for HAV infection. An inactivated HAV vaccine is available for individuals at risk for HAV infection. Passive immunization with HAV immune globulin is recommended for post-exposure prophylaxis in individuals exposed to infection but not previously immunized. Handwashing is an effective means of prevention.
Name That Virus! --Orthomixoviruses --Enveloped, negative single-stranded RNA viruses with 8-segment genome --Contain hemagglutinin (promotes viral entry) and neuraminidase ( promotes progeny virion release) antigens. --Patients at risk for fatal bacterial superinfection --Rapid genetic changes
Influenza Viruses
Rhinovirus Major Signs and Symptoms
Initial: sneezing followed by rhinorrhea Later: Rhinorrhea increases and is accompanied by symptoms of nasal obstruction (profuse watery discharge) -----mild sore throat, headache, malaise, cough, little or no fever
Major Human Coronavirus Proteins Proteins N (nucleoprotein)
Location Core Functions Ribonucleoprotein
Major Human Coronavirus Proteins Proteins E2 (peplomeric glycoprotein)
Location Envelope spikes (peplomer) Functions Binding to host cells; fusion activity
Major Human Coronavirus Proteins Proteins L (polymerase)
Location Infected cell Functions Polymerase activity
Major Human Coronavirus Proteins Proteins H1 (Hemagglutinin protein
Location Peplomer Functions Hemagglutination
What are some major RNA viruses?
MEASLES MUMPS RSV Influenza Coronaviruses Coxsackie Ebola Rotavirus Rabies
Name That Virus! --Koplik spots (red spots with blue white center on buccal mucosa) and descending maculopapular rash or characteristic. ----- Small white lesions with an erythematous halo that proceed the ____(?)____ rash by 1-2 days --Rash of ____(?)_____ (discrete erythematous rash becomes confluent as it progresses downward --SSPE (subacute sclerosing panencephalitis, occurring years later) -- Encephalitis( 1:2000), and giant cell pneumonia (rarely, in immunosuppressed) are possible sequelae. --Cough, Coryza, Conjunctivitis -- Rash presents last and spreads from head to toe. Includes hands and feet (vs truncal rash in rubella) -- Do not confuse with roseola (caused by HHV-6)
Measles virus
Family CORONAVIRIDAE
Members CORONAVIRUS Diseases SARS (Severe acute respiratory syndrome) SARS-Cov-2
Family Filoviridae
Members EBOLA virus Marburg virus
Family ORTHOMYXOVIRIDAE
Members INFLUENZA virus types A,B, and C
Family Picornaviridae Mnemonic: PEE Co Rn A viruses (Polio, Entero,Echo Coxsackie, Rhino, Hep A)
Members POLIOvirus Enteroviruses Echoviruses Coxsackievirus Rhinoviruses Hepatitis A virus
Family PARAMYXOVIRIDAE
Members Parainfluenza virus Sendai virus MEASLES virus Mumps virus Respiratory syncytial virus Metapneumovirus
Family Rhabdoviridae
Members RABIES virus vesicular stomatitis virus
PaRaMyxoviruses
Parainfluenza---croup RSV---bronchiolitis in babies; Rx--- ribavarin Measles Mumps
Name that Virus! Clinical Presentation Dermatologic Rash Findings/LABS Beginning at head and moving down; rash preceded by cough, coryza, conjunctivitis, and blue-white (Koplik) spots on buccal mucosa
Pathogen MEASLES Virus
Picornaviridae family
Poliovirus---polio-Salk/Sabin vaccines-IPV/OPV Echovirus---aseptic meningitis Rhinovirus---"common cold" Coxscackievirus---aseptic meningitis; herpangina (mouth, blisters, fever); hand, foot and mouth disease; myocarditis HAV---acute viral hepatitis PERCH
What is PML? What causes it?
Progressive Multifocal Leukoencephalopathy, ---subacute demyelinating disease ----Autopsy shows foci of demyelination w/ oligodendrocytes containing inclusion bodies only in the white matter caused by the JC virus.
Fill in the Blank: ________ viruses must encode their own polymerases (transcriptase and replicase)
RNA
Name That Virus! --Negri bodies are characteristic cytoplasmic conclusions in neurons infected by ______ virus ----- commonly found in Purkinje cells of cerebellum -- Has long incubation period (weeks to months) before symptom onset. -- Travels to the CNS by migrating in a retrograde fashion up nerve axons -- Progression of disease: fever, malaise ---> agitation, photophobia, hydrophobia ---> paralysis, coma ---> death. -- More commonly from bat, raccoon, and skunk bites than from dog bites in the United States
Rabies
Fill in the Blank: __________________, including HIV, are RNA viruses that use a DNA intermediate to replicate their genomes.
Retroviruses
Name That Virus! -The most important global cause of infantile gastroenteritis -- a segmented dsRNA virus (a reovirus). -- Major cause of acute diarrhea in the United States during winter, especially in daycare centers, kindergartens. -- Villous destruction with atrophy leads to decreased absorption of Na+ and loss of K+ Right Out The Anus
Rotavirus
This illustration provided a 3D graphical representation of a number of_____________ virions, set against a black background. Note the organism's characteristic, wheel-like appearance, which was made visible when viewed under the electron microscope. It's this morphology that gives the __________ its name, which is derived from the Latin rota, meaning "wheel". __________ are nonenveloped, double-shelled viruses, making them quite stable in the environment.
Rotavirus
What are the Target Cell and Receptor for Influenza A virus?
Target Cell Epithelial cells Receptor Sialic acid
A 45-year-old female horizon clinic complaining of a runny nose and sore throat for the past four days. She also complains of general malaise, headache, a nonproductive cough, and nasal congestion. She is afebrile, has mild erythema in her nasal passages, and has a watery nasal discharge. Her pharynx appears normal, and her lungs are clear. She has tender anterior cervical lymph nodes. What immune cells are involved in immune responses infection? Would you recommend an antibiotic?
The symptoms are consistent with Rhinovirus. The initial innate response would involve natural killer (NK) cells. The adaptive immune response would be mediated by CD8 cytotoxic T lymphocytes (CTL), which requires CD4 T cells to develop. You should not recommend antibiotics because it is a viral infection.
Name That Viral Family! Envelope No RNA structure SS (POSitive) linear Capsid symmetry Icosahedral Medical importance Norovirus--- viral gastroenteritis
Viral Family Calciviruses
Name That Viral Family! Envelope Yes RNA structure SS (NEGative) linear Nonsegmented Capsid symmetry Helical Medical importance PaRaMyxovirus: Parainfluenza--croup RSV--bronchiolitis in babies;Rx--ribavarin Measlese, Mumps
Viral Family Paramyxoviruses
Name That Viral Family! Envelope Yes RNA structure SS (POSitive) linear Capsid symmetry Icosahedral Medical importance Rubella Eastern equine encephalitis Western equine encephalitis
Viral Family Togaviruses
What are the Influenza pandemics resulting from Antigenic Shift?
Year of Pandemic Influenza A Subtype 1918: H(sw)N1; probable swine flu strain 1947: H1N1 1957: H2N2; Asian flu strain 1968: H3N2; Hong Kong flu strain 1977: H1N1 2009: H1N1 pdm09
Sudden shift is more deadly than
gradual drift
Where do rhinoviruses replicate?
in ciliated epithelial cells in the nose
This illustration depicted a 3D computer-generated rendering of a half-sliced__________ virus with a grey surface membrane, set against a black background. The virus' surface proteins, hemagglutinin (HA) and neuraminidase (NA), were highlighted in light and dark blue, respectively. HA is a trimer, which is comprised of three subunits, while NA is a tetramer, which is comprised of four subunits, with a head region resembling a 4-leaf clover. Inside the virus, its ribonucleoproteins (RNPs) were shown, with their coiled structures, and three-bulbed polymerase complex on the ends. An influenza virus' RNP is composed of both, RNA and protein. Every influenza virus has eight RNP segments, corresponding to the virus' eight total gene segments. Three of these RNP segments, encode the virus' surface proteins, i.e., the HA, NA and M proteins.
influenza
Coronavirus is a (nucleic acid structure) ______________ virus.
positive ssRNA
Fill in the Blank: With the exception of _____________, most togaviruses exist in well-defined geographical areas where mosquito vectors and host species determine the extent of virus survival and spread to humans. Important zoonotic pathogens include the three equine encephalitis viruses of the Americas. Chikungunya virus is now widely recognized as a significant cause of febrile illness accompanied by arthralgia. More serious complications have been observed in recent years. In contrast ___________ is endemic worldwide: although a mild childhood exanthema, infection of non-immune pregnant woman can result in serious congenital malformations.
rubella
