Micro exam 3
Infectious dose
# of microbes necessary to establish infection
Animal Virus Replication #3 Synthesis of Viral proteins and Replicaiton of Genome
--hijacks the living host cell -Uses the host cell ribosomes to make proteins -Synthesizes more of its nucleic acids and parts to make tons more Depending on the type of virus, There are 3 replication strategies: A. Replication of DNA viruses B. Replication of RNA Viruses C. Reverse Transcribing Viruses
Antigentic shift
-A major change due to a new gene segement Example: H1N1 -occurs in Inflenza A only -two differnt strains of the virus enters the host cell at the same time -genes between the two are mixed and recombined to form one NEW influenza virus with some of both
Asymptomatic Carriers
-A person who harbors the infectious agent with no signs/symptoms of infection -Do not take precautiosn -May sheed pathogen intermitelty or constantly for weeks, months, yeats 1. exposed to pathogen -no s/s during the incubation period -still infectious during this time 2. exposed to pathogen -sick with or without s/s -recover-->still shed pathgon=infectious
Provides benefical molecules to the host
-Carried out by intestinal bacteria and yeast; mainly bacteria -Types of bacteria have this ability: Bacteroides sp., Lactobacillus sp., Bifdobacterium sp., E. coli, Bifdobacterium sp, in general the Phylum Proteobacteria
Pathogenesis SARS-CoV-2
-Destroys Type II alveolar cells (secrete surfactant) -Attaches to the ACE-2 receptors (Angiotensis converting enzyme) -these receptors are found in the lungs, blood, heart, kidnesy, liver, & GI tract (lining) -Prevents ACE-2 receptors from doing its job (putting the breask on inflammation &BP)
C. RNA genome- Reverse Transcribing Viruses
-Encodes the enzyme Reverse Transcriptase -Synthesizes DNA from a strand of RNA -Example; Retroviruses like HIV, HTLV -These are also incorporated into host cell genome called Latent or Provirus
Animal Virus Replication: 2. Penetration and Uncoating
-Enveloped Viruses do it one way, naked viruses do it another way! -Enveloped Viruses enter the host cell by: A. Fusion with membrane-lipid bi-layer fuses with the cell membrane after attachement. Then nucleocapsid is releashed directly into cytoplasm B. Endocytosis-vessicle formed, enveloped fuses with vesicle. Then releases nucleocapsid into cytoplasm -Naked viruses enter the host cell by: 1. Direct pentration -viral genome goes directly through host cell phospolipid bilayer membrane 2. Endocytosis -Virus will destroy endosome, then released into cytoplasm
Envelope Virus Disadvantages
-Evenolped viruses are fragile -Conditions that damage membranes; will damge the envelope (heat, freezing, pH change, lipid solvents, chemical disinfectants like chlorine and hyrogen peroxide) -Naked viruses are generally tougher
Handful of viruses known to cause cancer:
-Human papilloma virus-cervix, vulva, vagina, penis, anus, back of throat (oropharynx) -Hepatis B-Liver -Epstein-Barr-nasopharyngeal, burkitt lymph -Hepatis C-Liver -Herpes virus-type-8-Kaposi Sarcoma (connective tissue) -Human T-lymphocyte virus-leukemia, lymphoma
Animal Virus Replication: 1. Attachment
-In enveloped viruses, spikes on the virion attach to receptors on the living cell -In naked viruses, the capsid attaches to receptors on the living host cell -Ther are hundreds of thosands of receptors on host cells, usually only need 2 to attach
How long does SARS-CoV-2 live?
-Lab studies-surfaces 7 days, cotton 4 days -Real world studies-3 days
Viral Componets: Envelope Virus Advantages
-Membrane "looks" like cell, hides virus from the immune system -Helps virus infect new cells by membrane fushion with a new host cell
Clostridium botulinum
-Produces endospores, endotoxin -Causes botulism -unpasteurized honey -impoperly canned vegatables Neurotoxin blocks acteylcholine at the neuromuscular junction -Prevents contraction of the muscle Botox
Animal Virus Replication: 4. Assembly (aka Maturation)
-This is simply when the virus particles are assembled together to form virions -Number of viruses produced depends on type of virus and size and intial health of host cell
The role of viruses in cancer
-Viruses cause 20-25% of human cancer -Some carry copies of oncogenes as part of their genomes -Some promote oncogenes already present in host -Some interfere with tumor repression
Viral Diseases (Gastroenteritis)
-caused by Norovirs, Rotavirus -may be caused by other microbes as well -other names: stomach flu, gastric flu, stomach bug -s/s: nausea, vomitting, watery diarrhea (fever rare)
Why are there so many strains of Influenza?
-changing protein spikes (surface antigens) -Antigentic drift is responsible for mutations that cause different strains each year (occurs in Influenza A&B) -reason why we get vanccinated each year -one virus enters the host cell and mutations occure in the replication, slightly different N and H protein spikes
SARS-CoV-2 characteristics
-coronavirus -envelope -helical capsid -RNA -Enters host through multiple methods (transmission)
SARS-CoV-2 transmission
-droplet, airborne, direct, indirect-fomites, fecal-oral
Competive Exclusion of Pathogens
-microbiota cover binding sites that could be used for attachment by pathogens -microbiota consumes most of availble nutrients, keeps it from pathogens
Produce Toxins/Antimicrobial substances
-microbiota produce toxic molecules that prevent the growth of other microbes, potential pathogens Examples: -Propionibacterium sp. lives on teh surface of the skin. It degrades lipids, releasing fatty acids. the fatty acids inhibit the growth of some pathogens. -Lactobacillus sp. lives in the vagina. It produces lactic acid. The acidic conditions (low pH)prevents the growth of some pathogens -Bifidobacterium sp. produces bacteriocin which is an antibacterial property. This compound helps to prevent the growh of Listeria monoctogenes
Structure of a virus:
-nucleic acid surrounded by a protein coat; Nucelocapsid -the nucleic acid part can be DNA or RNA (not both)
Growing Viruses
-obligate intracellular parasites: can't just grow on nutrient-rich agar like bacteria -must provide cells for them to infect -some viruses can be frown in cell culture (e.g, cancer cells growing in the bottom of a dish) -Malignant cells are "immortal" -Some viruses must be grown in anmials, or embryonated chicken eggs -Influenza virus vaccines are made in chicken egg embryos
Herpes Infection
-signs and symptoms -Slow spreading skin lesions -recurrence of lesion is common -pathogens and virulence factors: -caused by human hepesviruses 1 &2 -Produce various proteins that act as virulence factors -Pathogenesis -virus infects nerves of specifc Ganglia -painful lesion caused by inflammation and cell death
Viral genomes come in all kinds:
-single or double stranded, RNA or DNA -Linear or circular -one piece or segmented (in several fragments) -The capsid part is made up of capsomers (the little plates) -Some viruses have a phospholipid; Envelople -The viruses that do not have an envelop eare called NAKED Viruses
Trains/stimulates parts of the immune system
-the body's immune cells learn the difference between harmless and pathogenic organisms -stimulates the production of IgA. IgA is found in mucus membranes and works by attaching to pathogens
Persistent viral infection
-years or for life -A. Chronic - contious production of virus particles -usually in the absence of disease symptoms -can transmit through blood and body fluid to others without symptoms -B. Latent -viral genome remains silent in cells until triggered to reactive -when reactivated, produciton and relse of viruses occurs
Choose the correct statement about replication strategies of viruses.
1. DNA viruses enocde their own enzymes like DNA polymerase 2. Influenza virus uses replicase and it occurs in the cytoplasm of the cell
Reserviors of Infections: The natural habitat of the pathogens
1. Environment 2. Humans 3. Animals
Virulence Factors
1. Enzymes releasehd from the pathogen 2. Toxins 3. Structures for movement: flagella-bacteria, hyphae-in fungi, think roots (ex: Candida albicans (yeast infections), Trichonphyton sp.(toenail fungus)) Cillici-in Protozoa (ex: Balantidium coli (fecal/oral transmission/tropics) Ameboid movement-Protozoa (Ex: Nagelra fowden (brain eating amoeba) 4. Structures for attachement: pili-surface of pathogen, adhesions-gluelike molecule, Attachment proteins on surface of pathogen, EPS of biolfilms 5. Host cell invasion techniques: phagocytosis of macrophages, endocytosis of viruses
What are the three major shapes of viruses
1. Icosahedral 2. Helical 3. Complex
List the 11 portals of exit
1. Respiratory Tract 2. Urine 3. Feces 4. Cuts 5. Needles 6. Blood sucking arthropods 7. Aerosois 8. Skin 9. Blood 10. Salivary 11. Droplets
Charateristics of viruses
1. Very small, 100 to 1000x smaller than cells they infect 2. Can only by seen with an electron microsope 3. Minuscule, acellular, infectious agents having either DNA or RNA 4. Cause infections of humans, anmials, plants, and bacteria 5. Cause most of hte diseases that plague the industrialized world 6. Cannot carry out any metabolic pathway 7. Neither grow nor respond to the environment 8. Cannot reproduce independently, considred Obligate Intercellular Parasite 9. Recruit the host cell's metabolic pathways to increase their numbers 10. No cytoplasmic membrane, cytosol, or organelles
List the three types of molecules detected by the tests in the animation.
1. Viral RNA 2. Antigens 3. Antibodies
Describe 3 ways viruses may be released from infected cells
1. cell death-when a cell dies and it bursts parts of the virus spread to other cells 2. Budding-a virus aquires its envelope through the membrane of an organelle 3. the vesicles that are membrane bound fuse with the plasma membrance which releases their content
List and describe the 4 portals of entry
1. inhalation-occurs when inhalation happens via the respiratory tract 2. Absorption-viruses can be absorbed through mucous membranes (ex:eyes) 3. Ingestion-viruses can be ingested while eating; occurs in the gastrointestional tract 4. Inoculation-viruses can enter through open wounds
There _____ major types of viral infections
2; acute and persistent
Which Influzena type causes the most serious disease?
A
Explain latency in animal viral infections. THEN, give 4 examples of viruses that may go latent
A virus can remain dormant within a host cell. This can lead to a lifelong infection. Some examples are herpes simplex virus (HSV)-1, varicella zoster, adenovirus, and Epstein-Barr
For each vaccine type in the animation, propose a test that could detect an active viral infection without false positives from that vaccine. (Hint: It may help to review the tests for active infections in the Detection animation. Note that there may not be a good test in every case.) A. Inactive whole virus B. Antigen proteins C. Genetic instructions (DNA or mRNA)
A. Not a great test to test for this B. PCR Test C. PCR or Antigen Test
Animal Virus Replication #3 Synthesis of Viral proteins and Replicaiton of Genome Part 2
A. Replication of DNA Viruses -Most replication occurs i nthe nucleus -Viruses encode their own enzymes like DNA polymerase Example: Human Papilloma Virus, Herpes: These are incorporated into host all genome then called: Latent or Provirus
Antigen protein vaccines deliver the spike protein directly into the body. The DNA and mRNA vaccines, however, make the cells of the body generate the spike protein. Briefly describe how the body generates spike proteins for each vaccine type. A. DNA vaccines B. mRNA vaccines
A. not avaible in the USA, inactivated adenovirus, transcribe DNA into mRNA, ribosomes translated into spiked proteins. B. artifical membrane, similar to cell membrane, cells ribosomes translate mRNA into the spiked proteins
Figure 1 shows that remdesivir "mimics" an important component of RNA replication. Which component of RNA replication has a structure similar to that of remdesivir?
Adenine
Scientists discovered the SARS-CoV-2 is 10 to 20 times more likely to bind to these receptors than other coronavirus was. Predict how this increased change of binding has affected SARS-CoV-2's ablility to replicate.
Because it can bind to these receptors easier meaning it can infect more people at once allowing from more transmission (replication)
Why are naked viruses generally more resistant to disinfectants than are enveloped viruses?
Because the envelope is fragile and non eveloped viruses are more resistant to changes in pH, temperature
What is one song we heard in class and what was the body part mentioned?
Billie Jean-don't go around breaking young girls' hearts
Compare and contrast antigenic drift and antigenic shift
Both produce new strains of influenza-virus. But antigenic drift happens every 2-3 years when a single strain of influenza-virus mutates within a local population. Antigenic shift happens every 10 years and happens when genomes from different influenza-virus strains reassort within a host cell
Animal Virus Réplication: 5 Release
Budding: -Most enveloped viruses are released by BUDDING -budding=virus acquires envelope from the plams membrane, Golgi, or ER of host cell -Notice that this will include viral proteins that were produced using the viral nucleic acid. Thease are the "new" protein spikes -Most viruses will trigger apoptosis as they exit the cell. -Some released by LYTIC, bursting it open -Naked viruses are predominantly releasehd by host cell lysis. While some viruses lyse the hsot cell more or less directly, in many cases it is the body's immune defense that lyse the infected cell
Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?
Cell cultures and embryonated eggs
Propose a hypothesis about how remdesivir might inhibit the virus's replication process.
Cells most likely recognize it as one of their own nucleotide base, remdsivr will go where adenine is supposed to go. Prvents RNA from forming a mutation, can be indtroduced making the RNA useless
-2019
China-->Jan 2020 U.S. SARS-CoV-2 characteristics
Each of the following statements describes a step in the replication of SARS-CoV-2. These steps are listed in random order. Read through the steps and, in the spaces provided below, list them in the order they occur in the body. A. The virus relases its RNA genome into the cell B. Viral RNA polymerase helps transcribe more copies of the virus's RNA. C. The virus binds to a receptor on a human cell's membrane. D. New viruses travel to the cell membrane of the infected cell and are releashed outside the cell. E. The virus's RNA is translated into proteins by the cell's ribosomes.
Correct order: CAEBD
Herpes (oral and genital)-causes, symptoms, diagnosis, treatment, pathology
Cuase by teh herpes simplex virus (HSV), symptoms include sores and blisters at infections site, can be diagonised by a physcial examinateion and a viral culture, treatment is usually antivirals, hepres is a nuclear replication enveloped virus
Which viruses are easier to destroy; enveloped or naked, and WHY?
Enveloped are easeir to destroy because substances that damage members will damage the envelope therefore destroying the virus
Not all viruses have an envelope
Enveloped virus has one, Naked virus does not have an envelope
Which is true of viruses?
Enveloped viruses penetrate the host cell via fusion or endocytosis
Types of outbreaks
Epidemic=large # of cases in a population, greater than the normal (baseline) Pandemic=spreads worldwide; more than 1 continent
Protein Spikes: amount and type are used for classification (naming specific strains, usually just for Type A
Examples: H1N2, endemic in humans, pigs, & birds H1N1-caused Spanish Flu in 1918 and swine flu in 2009
Protein Spikes H=
Hemagglutinin
Name the virus that may cause cancer which is sexually transmitted
Human papilloma virus (HPV)
DNA Viruses
Incorporate their nucleic acids into the hosts genome
What is a virus? How do viruses work?
Infective agent; can only multiple in living cells of a host, contains DNA infects healthy cells and makes them multiply
What impacts might mutations have on the transmission of the virus?
It can increase transmission or decrease transmission or can have no affect.
When SARS-CoV-2 replicates in cells, mutations can occur in the virus's genome. Explain how a mutation (insertion, deletion, or substitution) in one of the virus's genes might affect a protein it encodes.
It will make every gene replicated after that will have the mutation. It can have no affect on the protein or it changes the structure of the protein changing the function.
In which type of viral infectiosn do viral genomes ramin silent in cells until triggered to reactivate and start making new virions?
Latent
Choose the correct statement about viral infections
Latent viruses can remain silent in host cells unitl triggered to reactivate
Staphyloccus aureus
MRSA-Methicilin Resistant S aureus by the late 90s strains of MRSA resistant to vancomycin -2 varieties: Community Acquired (CA) and Healthcare Acquired (HA) -on that makes up microbiota--> Commonly found on/in body -nasal mucosa: many people are colonized -not all stapharous is MRSA -5-10% colonized with MRSA infection
-2012
Midwest and Korea, Middle East Acture Respiratroy Syndrome MERS
Body Regions
Nasal, oral, skin, gastro-intestinal, urogential
N=
Neuraminidase
What do the H and N stand for in strains of Influenza like H5N1.
Neuraminidase, Hemagglutinin
Do the antigen protein vaccines contain all the proteins in the virus? If not, which protein(s) do they contain?
No, they contain the spike proteins
Are viruses alive?
No. They do not fit the criteria for a living thing. One fo the ways they do not is that they do not have the ability to reproduce on their own, viruses need a host cell to do that
B. Replication of RNA viruses
Occurs in cytoplasm -Uses viral RNA polymerase (AKA Replicase in Viruses) -Lack proofreading capabilites before trnaslation; this results in many mistakes we call mutations -Example: Influenza, SARS-CoV-2
Animal Virus Replication #2 continued
Once inside..... -DNA viruses go to the nucleus to mulitply -RNA multiply in the cytoplasm -ALL will then separate from their protein coat-uncoating -Uncoating releases the nucleic acids and enzymes
As shown in the animation, SARS-CoV-2 uses the ribosomes inside human cells to translate its RNA into viral proteins. According to the animation, what is on of the viral proteins made by the ribosomes, adn how does that protein help SARS-CoV-2 make more copies of itself?
One viral protein is the RNA polymerase and it makes copies of the viruses RNA.
Do the genetic instructions (DNA and mRNA) vaccines contain the virus's full genome? If not, what region(s) of the genome do they contain?
Only the spiked protein is made because it only has the instructions for that
Which of the following enzymes allows retroviruses to transcribe DNA from RNA?
Reverse transcriptase
All of the following viruses may cause the common cold except?
Rotovirus (adenovirus, coronavirus, rhionvirus can cause the common cold)
Explain how the terms COVID-19, SARS-CoV-2, and coronavirus mean different things.
SARS-CoV-2 is the name of the virus while COVID-19 is the disease caused from the virus. Coronavirus is a type of SARS-CoV-2
-2002/2003
Severe acute respiratroy syndrome SARS, China
Choose the correct statement about Norovirus
Signs and symptoms include, nausea, vomiting, and diarrhea
Syptamic
Symptoms-Felt by pateint Signs-observed by others -People w/symtoms are an bosivosu source of infectious agents -Take precautions not to transmit
Viral Diseases
The common cold: -upper respiartory infection -caused by: Rhinovirus, Coronavirus, Adenovirus -S/S usually no fever with rhinovirus, runny nose, cough, sore throat -Pathogenesis-Respiratory epitheial cell destrucition
Define infectious dose
The minimum # of microbes necessary to cause an infection to proceed.
Explain incubation period
The period of time that a person becomes infected to the time when they actually have symptoms, it is the most infectious (contagious) time
Propose an explanation for an indivduals test results that has a negative RT-PCR Test, Negative Antigen Test, and a Positive Antibody Test.
The person has had the virus in the past but has recoverd from it (no active infection)
Propose an explantion for an indivuals test results with a postive RT-PCR Test, Postive Antigen Test, and a negative antibody test
The person has the virus but they have not recovered from it yet (active infection)
What is the function of the spike protein?
The spikes attach to specific proteins on the surface of the cells.
Which of the following is a characteristic by which viruses are classified?
Type of nucleic acid
Describe virulence. Then give two virulence factors of pathogens.
Virulence is the harmfulness of a posion or disease. Two virulence factors are the capsule and flagella of a virus
Virulence
a measure of the pathogenicity (how destructive is the pathogen)
Pathogenicity
ability of a microorganism to cause disease
Infectious
able to be transmitted from one host to another AKA contagious or communicable
In viruses, protein spikes on the outer surface are responsible for?
attachement; 2 spikes needed
which are larger; bacteria or viruses
bacteria (02-4 microns, Viruses 5 microns-200 nanometers, SARS-CoV-2 100 nanometers)
Septicemia (sepsis)
bacteria and/or bacterial toxins in blood
A(n) ______ is a virus that infects bacterial cells
bacteriophage
The process known as ________ is a mechanism of release for enveloped viruses.
budding
Taxonomy
classification of viruses
Describe the shape and location of SARS-CoV-2's protein spikes.
clubbed shaped; stick out from the viral envelope
Outbreak
cluster of cases, affecting a particular population
Endemic
diseases constantly present in a population ex: common cold, influenza
Shift or Drift; Occurs in Influenza A and B
drift
Shift or Drift; Responsible for the mutation that occur from year to year
drift
Shift or Drift; Results in slightly different H and N protein spikes
drift
Transmission
droplet, direct, indirect, airborne (maybe) -Incubation about 24-28 hours -Adults 2-4 year children more virus mutates quickly. We also do not have much memory with these types of viruses Concern: secondary infections-occurs during or after treatment/ recovry for another infection -The primary infection makes host more susceptible to disease
compostion resemebles that of a cell membrane from which it came
envelope
Viruses are typically referred to as their
family name
Prebiotics
food we eat that is metabolized by intestinal bacteria, usually high fiber foods
Clostridium tetani
found in the soil -produces endospores, produces endotoxin -Anaerobic -Contact with muccus membrane, puncture wound -Cell release a neurotoxin -Blocks inhibitory neurotransmitters -turns on all of the motronuerons
Name the virus that may cause cancer of the liver
hepatis
bacterermia
if bacteria gets into the blood, continues to grow
Predict how mutations in the gene that encodes the spike protein might affect the types of cells the virus infects
if the genes mutate int a different shape it can change the receptor it attaches to
_____ can be localized to a specific area wound, cut, burn, region of body
infection
Some______ lead to colonization of the host
infections
What is the pathogenesis of gastroenteritis
infects the epithelial cells of the small intestine, causes destruction therefore interferes with secretion and absorption of fluid and nutrients
Propose an explanation for an indivduals test results that has a postivte RT-PCR Test, Negative Antigen Test, and a Negative Antibody Test.
is infected (active), antigens may not be present int eh sample, can have a lot of false negatives (antigen test)
human microbiome
is the total of all microorgansims (bacteria, viruses, and single celled eukaryotes) living in association with the human body
What are 2 ways viruses are cultured (grown) in a lab?
lab animals and embryonated eggs
the study of ecology
learning about the habitats and interaction between the microbes and the host and also between the microbes themselves
Envelope is a
lipid bilayer membrane acquired from a host cell membrane when virus "buds" (plasma membrane) or passes through a membrane bound organelle (such as the nucleus)
Probiotics
live microorganisms that offer a health benift if it takes up residence
Prions destroy which cells
neurons
Some viruses carry_____ as part of the genome, they are known to cause cancer in humans
oncogenes
Most animal viruses only infect
one species
Define pathogeneis
pathogenesis is the development of a disease and what leads to the disease
Infection
pathogens overcome the body's defenses natural resistance then multiply and become established in body
Colonization
presence of pathogen (usually baceria or fungi) of the body's surface (skin), nose, mouth, intestines (think mucus membranes) without cuasing disease in the host
Glycoproteins
proteins bound to carbohydrate, stick out from envelope
Shift or Drift; H1N1 is an example
shift
Shift or Drift; Occurs in influenza A only
shift
Shift or Drift; Two different strains of the virus enter the host cell at the same time
shift
Where is microbiota found on the body?
skin, any place that has a mucus membrane; digestive tract, urogenital tract; the skin and large intestine house the most
Some envelopes have
spikes; are important for attachment ot host cells
Epidemiology
study of patterns of disease in populations
Acute viral infection
sudden onset, usually short duration
"Pathos"
suffering
Pathogenesis
the harm the pathogen is doing to the host ex: destroys epithelial cells in host; killer helper T-cells
Virion
the name for one virus particle
Influenza (The Flu)
upper and lower respiratory infection caused by: Influenavirals (Family Orthomyxom viruses) -3 human types: A,B,C -s/s fever, headache, cough, mucle pain, sore throat Transmission: Droplet,direct interest, airborne (likely) Pathogenesis: Destroys respiratroy epithelium -Incuabation is about 48 hours Treatment; Antivirals but in early stages only viruses grow resistent quickly Tamiflu-Prevents new viruses from being released from host cell Zoflueza-(new one from Japan) Blocks viral enzymes from making viral proteins
Human Microbiome Project
was launched by the National Istitues of Health in 2007 wiht the mission to generate the resources and expertise needed to charcterizee the human microbiome and anyalyze its role in healht and disease.
Virulence factor(s)
what the pathogen uses to harm the host, the more virulence factors a pathogen has, the more virulent it is
Latency of animal viruses
when animal viruses remain dormant in host cells, viruses are called latent viruses or proviruses. May be prolonged for years with no viral activity. Incorporation of provirus into host DNA is permanent