Virology Success

Which of the following is an acquired immunodeficiency syndrome defining condition? A. Pneumocystis pneumonia B. Chronic infectious mononucleosis C. Severe acute respiratory syndrome D. Malaria

A. Pneumocystis pneumonia

Which of the following is not a step involved in virus replication? A. Attachment B. Mitosis C. Penetration D. Release

B. Mitosis B. Lacking essential components for the synthesis of macromolecules, viruses are not able to reproduce by binary fission. Host cells are required to provide the synthesis of viral components. The replicative cycle has four stages: absorption, penetration (uncoating), eclipse (biosynthesis), and release (maturation). Viral replication in the host cell may result in cell death, chronic infection with no observable changes, or transformation of the infected cell into a cancerous cell.

Which of the following animals is the primary reservoir for the lymphocytic choriomeningitis virus? A. Dogs B. Rodents C. House cats D. Poultry

B. Rodents

Which of the following togaviruses is known to produce fetal defects? A. Influenza B. Rotavirus C. Rubella D. Varicella

C. Rubella

Acute retroviral syndrome is characterized by which of the following? A. Chronic recurrent infection B. Slow rate of virus replication C. High titer of autoantibodies D. Lack of detectable antiviral antibody

D. Lack of detectable antiviral antibody

A 50-year-old male presents to the emer-gency department of a hospital in Arizona in severe respiratory distress. He states that he has fatigue, headache, muscle aches and pain, and fever before he developed difficulty in breathing. He reports that he recently cleaned the loft of his barn and noted a large amount of rodent feces. He is most likely suffering from which of the following disease? A. Hantavirus pulmonary syndrome B. Rabies C. West Nile fever D. Yellow fever

A. Hantavirus pulmonary syndrome

Jaundice is a common clinical symptom of which of the following viral diseases? A. Hepatitis A B. Infectious mononucleosis C. Rabies D. Varicella

A. Hepatitis A is one of several infectious diseases characterized by liver damage and icterus (jaundice). The appearance of jaundice, in the icteric phase, is correlated by liver biopsy with extensive parenchymal destruction. Convalescence is usually accompanied by subsequent complete regeneration of the diseased organ.

Which of the following hepatitis viruses is typically transmitted by the fecal-oral pathway? A. HAV B. HBV C. HCV D. HGV

A. Hepatitis A virus is typically transmitted by the fecal-oral pathway. Hepatitis B, C, and G viruses are generally transmitted by blood contact. Hepatitis E virus is also transmitted by the fecal-oral pathway.

4. Which of the following has been declared eradicated by the World Health Organization? A. Smallpox B. Human T cell lymphotropic virus C. Hepatitis G virus D. Eastern equine encephalitis

A. smallpox The last natural case of smallpox was in 1977, and the World Health Organization declared the world smallpox free in 1979. Elimination of the virus was due to a worldwide vaccination program. Because of the highly contagious nature of variola virus, the cause of smallpox, the ability of the vims to produce severe infections, and the termination of routine vaccinations, the virus is considered a potential bioterrorism agent.

The virus that causes hepatitis B is characterized as a A. Defective DNA virus requiring delta virus to complete its replication cycle B. DNA virus utilizing reverse transcriptase C. Nonenveloped DNA virus D. Single-stranded RNA virus

B. DNA virus utilizing reverse transcriptase B. The hepatitis B virus is an enveloped, partially double-stranded DNA virus. During viral replication, full-length RNA transcripts of the viral genome are inserted into maturing virus particles. The viral enzyme reverse transcriptase then transcribes these RNA transcripts to a fulllength DNA strand but only partially completes synthesis of the complementary DNA strand— hence a partially double-stranded DNA genome.

The rapid diagnosis of rabies is best made by which of the following? A. Detecting Negri bodies in brain tissue B. Direct fluorescent antibody test of brain tissue C. Detecting antibody to the virus in serum D. Detecting antibody to the virus in cere-brospinal fluid

B. Direct fluorescent antibody test of brain tissue

Which of the following RNA viruses causes hepatitis and has a high incidence in countries with poor sanitation in handling human feces? A. Polyomavirus B. Hepatitis A virus C. Hepatitis B virus D. Hepatitis C virus

B. Hepatitis A virus

The use of cell cultures has enabled virologists to isolate and identify many clinically important viruses. However, because some viruses cannot be grown in cell cultures, these agents are best diagnosed by serologic testing. Such an agent is A. Cytomegalovirus B. Hepatitis C virus C. Herpes simplex virus 2 D. Respiratory syncytial virus

B. Hepatitis C virus has never been grown in culture. All knowledge of the virus and diagnostic reagents has been attained through molecular techniques applied to the RNA genome. Hepatitis C virus infection can be diagnosed by detecting antibody to the virus or by amplifying viral RNA from plasma. Cytomegalovirus, herpes simplex virus, and respiratory syncytial virus are readily grown in culture.

3. Characteristics of this DNA hepatitis virus include infections spread by contaminated body fluids, 50- to 180-day incubation period, and chronic infections. A. HAV B. HBV C. HCV D. HEV

B. Hepatits B virus is an enveloped DNA virus transmitted by contact with blood or via sexual contact. Most hepatitis viruses have a long incubation period of several weeks to months. Hepatitis A and hepatitis E viruses are RNA viruses primarily spread via the fecal-oral route. Hepatitis C virus is an RNA virus transmitted by contact with blood.

2. The appearance of Koplik spots in the oral mucosa of patients is characteristic of infection with what viral agent? A. Hepatitis B. Measles C. Rabies D. Smallpox

B. Measles (rubeola) is a highly infectious childhood disease. Infection with this vims is followed by a prodromal syndrome characterized by cough, coryza, conjunctivitis, and fever. The most characteristic lesions, Koplik spots, are seen on the buccal mucosa. Koplik spots are diagnostic for measles infection and represent necrotic vesicles with a white center surrounded by erythema.

Select the statement that is correct concerning the influenza A viruses. A. Humans are the only animal hosts for influenza A viruses. B. Pandemics are characteristically produced by influenza A. C. The incidence of infection peaks in the summer months. D. They are DNA viruses.

B. Pandemics are characteristically produced by influenza A. B. Influenza viruses are RNA viruses able to infect humans and other animals, such as birds and pigs. Influenza viruses are associated with epidemic and pandemic disease. There are two main types of influenza viruses (A and B), which differ antigenically and in epidemic periodicity. All recorded pandemics have been caused by influenza A viruses. The incidence of respiratory disease caused by these agents peaks during the winter months.

Mumps is characterized by an infection of the A. Central nervous system B. Parotid glands C. Pancreas D. Thymus

B. Parotid glands The mumps virus infects the parotid glands. Infection results in swelling of the neck. Mumps is primarily a childhood infection, and swelling of the parotid glands is diagnostic.

A baby was admitted to the hospital in February for dehydration due to severe diarrhea. Cultures for bacterial pathogens revealed normal fecal flora at 24 hours. Which of the following additional tests would be most appropriate given the case history? A. Heterophile antibody test B. Rotavirus antigen assay of stool specimen C. McCoy cell inoculation for cytomegalovirus (CMV) D. Urine microscopic analysis for presence of CMV cellular inclusion bodies

B. Rotavirus antigen assay of stool specimen B. Rotavirus is the cause of diarrheal disease in at least half of all infants and young children admitted to the hospital with dehydration requiring fluid replacement therapy. Because rotaviruses are difficult to propagate in cell culture, the method of choice for the detection of rotavirus infection is the direct examination of stool for the presence of viral antigen. Commonly used rotavirus antigen assay tests include latex agglutination and enzyme immunoassay.

An 18-year-old male presents to his family physician complaining of sore throat and fatigue. The patient is found to have a fever and swollen cervical lymph nodes. A complete blood count and differential reveal lymphocytosis and many reactive (atypical) lymphocytes. The physician should suspect an infection caused by A. Adenoviruses B. Epstein-Ban'virus C. Parainfluenza virus D. Varicella-zoster virus

B. The Epstein-BaiT virus , which is associated with Burkitt lymphoma and nasopharyngeal carcinoma, is the etiologic agent of infectious mononucleosis. Infectious mononucleosis is an acute disease most commonly affecting children and young adults. The virus is thought to be transmitted by intimate contact and has been called the "kissing disease." The patient's blood demonstrates a leukocytosis with a marked increase in T lymphocytes, and serologically the disease is characterized by a positive heterophile antibody and antibodies to various viral antigens.

Coxsackie viruses are associated with A. Gastrointestinal disease B. Hepatitis C. Myocarditis D. The common cold

C. Myocarditis C. The coxsackieviruses are enteroviruses named after the town of Coxsackie, New York, where they were first isolated. The viruses are divided into groups A and B on the basis of viral and antigenie differences. The group B coxsackieviruses are strongly associated with myocarditis that may cause sufficient damage to require heart transplantation. The group A coxsackieviruses are associated with various diseases, characterized by vesicular lesions, such as heipangina. Neither group of coxsackieviruses is associated with gastrointestinal disease.

Which of the following is the most clinically relevant disease associated with Zika virus? A. Pneumonia in the elderly B. Severe diarrhea in infants C. Neurologic disease in newborns D. Cancer in patients who are immuno-compromised

C. Neurologic disease in newborns

Poliovirus is a member of the family A. Flaviviridae B. Paramyxoviridae C. Picornaviridae D. Reoviridae

C. Picornaviridae C. Poliovirus is a member of the family Picornaviridae. These are small RNA viruses lacking an envelope. Other members of the family include coxsackieviruses, echoviruses, enteroviruses, and rhinoviruses.

1. The retrovirus responsible for causing acquired immune deficiency syndrome is a member of the family A. Orthomyxoviridae B. Paramyxoviridae C. Retroviridae D. Flaviviridae

C. Retroviruses are RNA viruses that replicate by means of DNA intermediates produced by the viral enzyme reverse transcriptase. The viruses associated with acquired immune deficiency syndrome are human immunodeficiency viruses (HIVs). These viruses belong to the family Retroviridae.

RNA-dependent DNA polymerase is also called A. Gyrase B. Neuraminidase C. Reverse transcriptase D. Transaminase

C. Reverse transcriptase C. RNA-dependent DNA polymerase is also known as reverse transcriptase. The enzyme uses an RNA template to synthesize the complementary DNA strand. The retroviruses require this enzyme for replication.

Which of the following childhood diseases is associated with human herpesviruses 6 and 7? A. Chickenpox B. Measles C. Roseola D. Zoster

C. Roseola

The togavims known to produce fetal defects is A. Influenza B. Rotavirus C. Rubella D. Varicella

C. The rubella virus is an RNA virus and a member of the family Togaviridae. In adults and children, rubella infections are generally a mild contagious rash disease. When a pregnant woman becomes infected, the consequences become more serious. If the fetus is infected during the first trimester of pregnancy, a variety of congenital defects may result. Anatomic abnormalities produced by this agent include cataracts, deafness, and cardiac problems.

14. The viral disease shingles, which causes extreme tenderness along the dorsal nerve roots and a vesicular eruption, has the same etiologic agent as A. Rubeola B. Vaccinia C. Varicella D. Variola

C. Varicella Zoster or shingles occurs predominantly in adults, whereas varicella occurs more commonly in children. The varicella-zoster virus, following the primary infection known as chicken pox, remains latent in the sensory ganglia. Reactivation of this virus, which occurs years later, is usually associated with a slightly immunocompromised state.

Human herpesviruses 6 and 7 are associated with a childhood disease called A. Chickenpox B. Measles C. Roseola D. Zoster

C.Roseola Human herpes viruses (HHVs) 6 and 7 cause the childhood disease roseola, also called sixth disease. The disease is characterized by fever, rash, and sore throat. More cases are caused by HHV 6 than HHV 7.

10. A 25-year-old patient presented with multiple vesicles around the mouth. Material from the lesions was obtained by needle aspiration and inoculated to MRC-5 cells. After 1 day, the cytopathic effect included foci of "ballooned" and lysed cells. These observations suggest infection with A. Adenovirus B. Cytomegalovirus C. Epstein-Barr virus D. Herpes simplex virus

D. Herpes simplex virus Cell cultures recommended for the isolation of herpes simplex virus (HSV) are human embryonic fibroblasts. The usual period needed to detect HSV destruction of the cell monolayer is 1 to 2 days. The more common of the two recognized types of HSV cytopathic effect begins with a granulation of the cytoplasm followed by cell enlargement and a ballooned appearance. Monoclonal antibodies and immunofluorescence are commonly used to differentiate between HSV-1 and HSV-2.

6. Kaposi sarcoma is associated with infection by A. Adenovirus B. Cytomegalovirus C. Hepatitis E vims D. Human herpes virus 8

D. Human herpes virus 8 During acquired immune deficiency syndrome (AIDS), as the immune system becomes weakened, the patient presents with chronic and recurrent infections and various neoplasms. Kaposi sarcoma, a relatively common cancer in patients with AIDS, has been linked to human herpes virus 8. Viral genome has been found in the cancerous growths in these patients.

The virus associated with warts is A. Flavivirus B. Morbillivirus C. Mumps virus D. Papillomavirus

D. Papillomavirus D. The etiologic agents for the numerous benign cutaneous and mucosal lesions known as warts are the human papillomaviruses (HPVs). The diagnosis of lesions caused by these agents is based on clinical appearance and histopathology, because there are no in vitro systems available for isolation. Some HPV types are strongly associated with squamous cell carcinoma of the cervix and anus.

The most common cause of cervical cancer is A. Cytomegalovirus B. Enterovirus C. Molluscum contagiosum D. Papillomavirus

D. Papillomaviruses are responsible for warts, including genital warts. Some serotypes of papillomavirus are associated with cervical cancer. A vaccine providing protection against these serotypes is available for women.

Molluscum contagiosum virus is a member of the A. Adenoviruses B. Herpes viruses C. Papovaviruses D. Pox viruses

D. Pox viruses Molluscum contagiosum is an infectious disease with a worldwide distribution caused by a poxvirus. Nodules develop in the epidermis of the face, arms, back, and buttocks, which undergo necrosis. Examination of epithelioid cells from affected areas will show characteristic eosinophilic cytoplasmic inclusions (molluscum bodies).

Negri bodies may be found in brain tissue of humans or animals infected with A. Adenovirus B. Filovirus C. Measles virus D. Rabies virus

D. Rabies is a neurotropic virus that causes extensive destruction in the brain. Negri bodies are seen in the cytoplasm of large ganglion cells and are demonstrated by Seller's stain. Rabies in humans or lower animals can be diagnosed by demonstration of these characteristic inclusions. However, the more sensitive direct fluorescent antibody test is more commonly used.

The etiologic agents of many common colds are RNA viruses that grow better at 33°C than at 37°C. These viruses are A. Adenoviruses B. Orthomyxoviruses C. Paramyxoviruses D. Rhinoviruses

D. Rhinoviruses , members of the picornavirus group, are a common cause of the respiratory disease known as the common cold. Hand transmission, not aerosols, appears to be the primary means of transmission. In contrast to other picornaviruses, the optimum temperature for rhinoviruses is 33°C.

Which of the following diseases is not associated with herpes simplex virus? A. Cold sores B. Encephalitis C. Genital herpes D. Thrush

D. Thrush D. Herpes simplex viruses (HSVs) are noted for causing a number of different diseases, notably cold sores (primarily HSV-1) and genital infections (primarily HSV-2). In neonates and immunocompromised individuals, they can produce encephalitis. They are also linked to severe eye infections. Thrush is an infection caused by the yeast Candida.

An example of a virus associated with latent infections is A. Influenza B. Rotavirus C. Rubella D. Varicella-zoster

D. Varicella-zoster D. Herpes simplex viruses, cytomegalovirus, and varicella-zoster viruses (VZV) produce latent infections. The genomes of these viruses can remain dormant in host cells for decades. Shingles (zoster) represents reactivation of latent VZV.

Although there have been no natural cases of this serious disease in about 30 years, which of the following is considered a potential bioterrorism disease A. Dengue B. Ebola hemorrhagic fever C. Shingles D. Smallpox

D. smallpox has not caused a natural infection since 1977, it is regarded as a potential bioterrorism agent. Routine vaccination against smallpox is no longer in effect, so the majority of the world's population is again susceptible. The U.S. has stockpiles of vaccine available to vaccinate everyone in the country in case of an attack.

A clinical specimen is received in viral transport medium for viral isolation. The specimen cannot be processed for 72 hours. At what temperature should it be stored? A. -80°C B. -20°C C. 4°C D. 22°C

A. -80°C Prolonged storage of clinical specimens for viral isolation requires -80°C. Specimens can be stored at 4°C for approximately 48 hours without appreciable loss of viability. Specimens should not be stored at -20°C for any length of time.

Enteroviruses are most often associated with A. Acute nonspecific febrile syndrome B. Bronchitis and pneumonia C. Lower respiratory tract infections D. Upper respiratory tract infections

A. Acute nonspecific febrile syndrome Most enterovirus infections are probably asymptomatic. Despite the name, these viruses are rarely associated with infections of the gastrointestinal tract. When symptomatic, they are most noted for producing acute nonspecific febrile syndrome.

9. Which of the following viruses is predominantly associated with respiratory disease and epidemics of keratoconjunctivitis? A. Adenovirus B. Molluscum contagiosum virus C. Norwalk virus D. Rotavirus

A. Adenoviruses are well known as respiratory pathogens and have been the cause of acute respiratory disease among military recruit populations. Also associated with adenoviral infection is the severe ocular disease keratoconjunctivitis, which typically occurs in epidemic form. Adenoviruses may remain in tissues, lymphoid structures, and adenoids and become reactivated.

7. The molecular receptor of the virus causing acquired immune deficiency syndrome is A. CD 4 B. CDS C. Fc receptor D. Complement receptor

A. CD 4 The human immunodeficiency viruses cause AIDS. The major target of the virus is the T helper cell, which would normally function to control disease. The virus initially binds to CD 4 found on the surface of T helper cells. Other coreceptors are also important for attachment.

Following a diagnosis of human immu-nodeficiency virus infection, the disease is staged based on which of the following? A. CD4+ cell count and opportunistic infections B. CD4+:CD8+ cell ratio and p24 concen-tration C. Anti-gp120 antibody titer and CD4+ cell count D. Anti-gp41 antibody titer and CD4+:CD8+ cell ratio

A. CD4+ cell count and opportunistic infections

Rhabdovirus is most noted for causing infections of the A. Central nervous system B. Gastrointestinal tract C. Lower respiratory tract D. Upper respiratory tract

A. Central nervous system Rhabdovirus causes rabies, an infection of the central nervous system. The virus is transmitted in the saliva of an infected animal during a bite. At the bite site, the virus initially infects muscle tissue, but will move to the peripheral nerves. The virus then migrates along the peripheral nerves to the central nervous system.

12. Which of the following is caused by a herpes virus? A. Cold sores B. Hemorrhagic fever C. Polio D. Rabies

A. Cold sores Members of the herpes virus group are responsible for a number of diseases, including cold sores. Hemorrhagic fevers are caused by a number of tropical viruses, such as Ebola and dengue. Polio is caused by a picornavirus, and rabies is caused by the rhabdovirus.

An 8-week-old infant was admitted to the hospital with symptoms of low birth weight, jaundice, and neurologic defects. Intranuclear inclusions were found in epithelial cells from the urine. The most likely diagnosis in this case would be infection by A. Cytomegalovirus B. Epstein-Barr virus C. Herpes simplex virus D. Rubella virus

A. Cytomegalovirus A. Infants usually acquire cytomegalovirus infections before birth or at the time of childbirth. These infections may lead to death during the first month of life or may result in residual neurologic impairment. The virus can be isolated from several different body fluids, with urine being the most commonly examined.

What is the most accurate test for identify-ing the presence of human papillomavirus? A. DNA hybridization B. Enzyme immunoassay C. Cell culture D. Serology

A. DNA hybridization

The "core window" refers to the time A. During hepatitis B virus infection when anti-HBc IgM is the only serologic marker B. During hepatitis B virus infection when HBc is the only serologic marker C. During hepatitis A virus infection when HAc is the only serologic marker D. During hepatitis C virus infection when the virus is latent

A. During hepatitis B virus infection when anti-HBc IgM is the only serologic marker During the course of acute hepatitis B virus infection, hepatitis B surface antigen (HBsAg) is the first marker detected. The host will ultimately begin to produce antibody (anti-HBs) to the antigen. As the antibody titer increases, there is a corresponding decrease in the antigen. However, there is a time period when neither of these markers is detectable. During this time period the only serologic marker is antibody to the hepatitis B core antigen (anti-HBc). This period is called the core window.

Characteristic cytopathic effect associated with respiratory syncytial virus is A. Giant multinucleated cells B. Basophilic intranuclear inclusions C. Eosinophilic cytoplasmic inclusions D. Shrunken cells with multilobed nuclei

A. Giant multinucleated cells A. Respiratory syncytial virus causes fusion of adjacent cells. This produces giant multinucleated cells called syncytia. Basophilic intranuclear and eosinophilic cytoplasmic inclusions are characteristic of cytomegalovirus infection.

A primary care provider suspects an 18-year-old patient has infectious mono-nucleosis. However, the serologic markers for the test are all negative. Which of the following is the most likely explanation? A. Varicella-zoster virus infection B. Cytomegalovirus infection C. Blood sample was taken too early in the course of the infection. D. False negative results due to the pres-ence of heterophile antibody

B. Cytomegalovirus infection

The tubular cells of the human kidney shed which of the following viruses for prolonged periods? A. Adenovirus B. Cytomegalovirus C. Epstein-Barr virus D. Rubella virus

B. Cytomegalovirus infections may be asymptomatic for normal healthy hosts. Infections tend to be more severe in patients who are immunosuppressed or in neonates infected perinatally. Cytomegalovirus is readily isolated from urine because it is shed by the tubular cells of infected hosts.

5. Rotavirus is the most common etiologic agent of A. Acute nonbacterial encephalitis in children B. Acute nonbacterial gastroenteritis in infants and young children C. Chronic nonbacterial pharyngitis in children and young adults D. Chronic nonbacterial retinitis in children

B. Acute nonbacterial gastroenteritis in infants and young children One of the major viral agents associated with cases of acute gastroenteritis in children is rotavims. In particular, this agent is the cause of epidemic nonbacterial gastroenteritis in infants and young children that occurs most commonly during the winter months. Rotavirus belongs to the family of RNA viruses known as Reoviridae. Rotavirus has a fecal-oral route of transmission and has been documented as a nosocomial pathogen in pediatric areas of hospitals.

After receiving the hepatitis B vaccine, immunity is indicated by the presence of which of the following? A. Hepatitis B surface antigen B. Anti-hepatitis B surface antigen anti-body C. Anti-hepatitis Be antigen antibody D. Anti-hepatitis B core antigen antibody

B. Anti-hepatitis B surface antigen anti-body

Influenza A virus undergoes recombination events that produce new strains; this is referred to as A. Antigenic drift B. Antigenic shift C. Reactivation D. Viral latency

B. Antigenic shift Influenza A virus undergoes recombination events that produce significant changes in the RNA genome of the virus. These changes lead to alteration of surface antigens. This process is referred to as antigenic shift. Antigenic drift is a slight change in a gene, usually a point mutation. Influenza A, B, and C viruses can undergo antigenic drift.

11. The Sabin polio vaccine uses which of the following? A. Formalin-inactivated viruses B. Attenuated viruses C. Recombinant viral antigens D. DNA

B. Attenuated viruses The Salk vaccine utilizes a formalin-inactivated poliovirus. The Sabin polio vaccine uses an attenuated virus; therefore, the virus is still able to infect cells and cause an asymptomatic infection. The Sabin vaccine provides a stronger immune response than the Salk vaccine.

Which of the following is the greatest risk factor for severe West Nile virus infection? A. Exposure to rodents B. Exposure to bats C. Age, over 60 years old D. Concurrent enterovirus infectio

C. Age, over 60 years old

Hepatitis C virus infections A. Are commonly diagnosed during the acute stage B. Are uncommon in the U.S. C. Are most often acquired by contact with blood D. Seldom results in chronic infection

C. Are most often acquired by contact with blood C. Hepatitis C virus infections, unlike hepatitis A or hepatitis B infections, do not commonly produce jaundice. There are tens of thousands of individuals in the United States chronically infected with hepatitis C; chronic infection appeal's to be the rule rather than the exception. Transmission of the virus at present occurs mainly through needle sharing. Cases also occur among healthcare workers who contact infected blood.

The poliovirus, an RNA virus, is a(n) A. Adenovirus B. Coxsackie virus C. Enterovirus D. Rhinovirus

C. Enterovirus Poliovirus, an enterovirus, is shed by both respiratory and fecal routes. Laboratory identification relies on isolation (especially from feces) and subsequent virus neutralization in tissue culture. Spread of the disease is associated with poor sanitary conditions and crowding.

Which of the following has not been successfully used to detect viruses clinical specimens? A. Cytopathic effect B. Enzyme-linked immunosorbent assay C. Growth on selective agar media D. Immunofluorescence

C. Growth on selective agar media C. Because of their nature as obligate intracellular parasites, successful cultivation of viruses requires living cells. Cell cultures provide host cell systems, which are easily handled, stable for long periods, and not susceptible to host factors such as stress or physiologic changes. Viruses are not like bacteria; they will not grow on any cell-free medium.

8. The type of cell culture that best supports the growth of cytomegalovirus is A. HeLa cells B. HEp-2 cells C. Human fibroblast cells D. Primary monkey kidney (PMK) cells

C. Human fibroblast cells Commercially available cell cultures of human fibroblasts are optimal for the cultivation of cytomegalovirus (CMV). CMV will not replicate in other cell cultures such as HeLa or HEp- 2. CMV can be identified with a high level of confidence solely on the basis of its characteristic cytopathology. Infected cells in the monolayer appear enlarged, rounded, and refractile.

Which of the following is associated with the rubella virus? A. It is a DNA vims. B. It is a member of the same taxonomic family as measles virus. C. It is known to produce defects in fetuses during the early stages of pregnancy. D. It is transmitted by an arthropod vector.

C. It is known to produce defects in fetuses during the early stages of pregnancy. C. The rubella virus causes an exanthematous disease resembling a milder form of measles in children. This single-stranded RNA vims, transmitted from person to person, is of medical importance to females of childbearing years because of the teratogenic effects it has on the fetus. Congenital rubella, resulting from an intrauterine fetal infection, is most severe when contracted during the first trimester of gestation.

Which of the following opportunistic diseases is not closely associated with acquired immune deficiency syndrome? A. Cryptococcosis B. Cryptosporidiosis C. Malaria D. Mycobacteriosis

C. Malaria C. The immunologic abnormalities demonstrated by patients with AIDS predispose them to a variety of opportunistic pathogens. The absence of a cellular and humoral immune response enables opportunistic organisms to cause extensive infection. Malaria is not an opportunistic infection.

Arboviruses A. Only infect humans B. Often cause hepatitis C. Typically infect lymphocytes D. Are transmitted by arthropods

D. Are transmitted by arthropod Arbovirus is short for arthropod-borne vims. These genetically diverse viruses share a common feature: They are transmitted by arthropods (e.g., mosquitoes and ticks). Arboviruses include West Nile virus and western equine encephalitis virus.

Which of the following is a characteristic of arboviruses? A. Only infect humans B. Often cause hepatitis C. Typically infect lymphocytes D. Are transmitted by arthropods

D. Are transmitted by arthropods

13. Which of the following is not a general characteristic of a virus? A. Obligate intracellular parasite B. Does not produce ATP C. Genome is surrounded by a protein coat D. Can self-replicate in the appropriate host cell

D. Can self-replicate in the appropriate host cell Viruses are obligate intracellular parasites that cannot self-replicate. They cannot produce ATP, and their genome is surrounded by a protein capsid. Most viruses contain either DNA or RNA; however, some large DNA viruses do contain viral mRNA and microRNAs.

A nasopharyngeal swab in bacterial trans-port medium is received in the laboratory at 8 a.m. The physician has requested a direct antigen test for influenza. The sample was collected at 6 p.m. the previous evening from a patient admitted to the hospital through the emergency department. You should perform which of the following step? A. Process the sample according to the package insert for the kit. B. Freeze the sample at −20°C for pro-cessing later that day. C. Place the swab into sterile saline and refrigerate until processed that day. D. Contact the physician and request an-other specimen.

D. Contact the physician and request an-other specimen.

Which of the following is a mild childhood disease caused by parvovirus B19? A. Measles B. Rubeola C. Rubella D. Erythema infectiousum

D. Erythema infectiousum