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160 Cards in this Set
- Front
- Back
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BV
Are viruses bigger or smaller than bacteria? |
Smaller
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Why are they considered "true parasites"
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Because they contain no mitochondria, ribosomes, golgi, or other cellular organelles of their own. They are completely dependant on the machinery of the host cell to produce energy and proteins.
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Do viruses ever have both RNA and DNA?
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NO!!
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With presence of a virus often comes interferon release. What are interferons?
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Interferons are proteins produced by cells of the immune system and induced by virus infection and double stranded RNA molecules. They act like hormones to other cells, working through a specific receptor. They induce anti-viral states in neighboring, uninfected cells by: (1) inhibiting translation of protein (protein kinase phosphoylates eIF2); (2) destroy mRNA (mediated by 2-5A synthtase; (3) inhibit protein synthesis
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What are the two essential components all viruses have?
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Protein (capsid) and nucleic acid (DNA or RNA)
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What are viral envelops?
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Coverings on top of viral capsids made of a combination of viral glycoproteins and host cell's membranes. They are used to help virus enter host.
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What is a capsid?
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A repeating series of protein subunits that surround the viral genome.
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What are the two types of capsids?
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Icosahedral capsid: nucleic acid is condensed in a core inside the structure. (ex. Polio, norwalk, adenovirus)
Helical capsid: linked in a "ribbon" that folds into a helix. (ex. influenza and mumps) |
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What is the function of a capsid?
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To condense, protect, and transport nucleic acids. While it also provides specificity for attachment.
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What part of the virus starts the actual infection? How?
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Capsids, they cause attachment of the virus on to the target cell as well as aide in the injecting of the genetic material into the host cell.
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How are viruses classified?
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Using their viral genetic information (their genome)
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What is unique about (-) RNA viruses?
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They cannot be translated directly into protein. Instead they must be first transcribed into mRNA. So they have to carry their own enzyme (RNA-dependant RNA polymerase) which transcribes the RNA into a complimentary strand (mRNA). This complimentary strand can then be translated into protein.
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How are most viruses taken up into the host cell?
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In coated pits which form vescicles.
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How are enveloped viruses released vs. naked ones?
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Enveloped ones bud through the cell membrane.
Naked ones are released when the cell lyses. |
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Can a virus reproduce on their own?
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NO! They must invade a cell, take over the cell's internal machinery and instruct the machinery to build new viruses.
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What four steps are needed in order for a virus to reproduce?
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1. adsorption and penetration
2. uncoating of the virus 3. synthesis and assembly of the viral products as well as inhibition of the host cell's own DNA, RNA, and protein synth. 4. release of virions from the host cell (either by lysis or budding) |
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What is "uncoating"?
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When the viral envelop fuses with endosomes membrane at low pH allowing nucleic acid to be released from the capsid into the nucleus or cytoplasm.
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What virus has a latent infection where its viral nucleic acids reside as extrachromosomal elements?
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Herpesvirus
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What is a persistent infection?
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One where there is continual shed of virus particles after the acute illness has passed. The amount of virus produced is lower than lytic cycle and virus production does not kill cell.
Note: persistant infection does not always manifest in overt disease |
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What are cytopathic effects? How is this information used?
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Damage to infected host cells caused infecting virus.
Different cytopathic effects can be seen in virus isolation and growth and used to identify viruses. |
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How can you "visualize the virus via the plaque assay"?
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The virus infects a cell, destroys it, and as it is doing this, plaques are created in the monolayer. These plaques can be visualized by vital stains.
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What is the mneumonic for Picornavirdae viruses?
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"I am (+) that there is a PERCH that pooped on the peak (pico)"
(+) ssRNA Polio, Echo/entero, Rhino, Coxsackie, HAV. Transmitted fecal-oral (and virus is in stool for 3-6 wks) |
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VIP
Where do piconavirdae viruses replicate? How? |
Since they are (+)ssRNA, they ARE mRNA and are translated into polyproteins. They polyproteins are then processed into proteases. This all happens in the cytoplasm.
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What is the season for piconavirdae viruses?
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Summer-Fall (in temperate climates)
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VIP
At what pH are enteroviruses (aka piconavirdae) resistant? |
pH 3.0 - 9.0
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Describe the structure of piconavirdae viruses?
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They have a icosahedral capsid that has ridges and canyons.
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Where does Poliovirus enter the body?
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In the intestinal and oropharyngeal mucosa and then into the lymphatic tissue.
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Does Poliovirus causes viremia?
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Yes
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What cells does Polio get to infect?
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Ones with a receptor.
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Is polio shed in feces?
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Yes for long periods of time
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What is the most common clinical presentation to polio?
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Asymptomatic (or mild "flu-like" illnesses)
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What are the four possible outcomes of a poliovirus infection?
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1. Asymptomatic illness (90%)
2. Abortive poliomyelitis (minor febrile illness, flu-like) 3. Nonparalytic poliomyelitis or aseptic meningitis (1-2%; virus progresses to the CNS causing back pain and muscle spasms + minor illness) 4. Paralytic polio (0.1-2%; get minor infection and then 3d after it goes away you get a major illness (biphasic) and the virus spreads from the blood to the anterior horn cells and motor cortex.) |
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Mneumonic for: Polio
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President Roosevelt (+RNA) just felt like he had the flu but he was shedding virus for a long time. Then 3-4 days later he became paralyzed.
He is in the top 1% of the population. |
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Since polio is a picornavirus what resistance does it have?
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It is resistant to pH 3-9
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VIP
What is post-polio syndrome? |
In 20-80% of the original victims of polio can get an induced poliomyelitis that can occur 30-40yrs later.
Infectious polio is not present but the syndrome is believed to be due to a loss of neurons in the initially affected nerves. |
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How is poliovirus detected?
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Using a throat (2d-2wks) or rectal swab (4mths) -- call CDC
Confirm with serology |
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VIP
How many doses of polio vaccine are needed to induce seroconversion? |
3, and anyone with polio can give a vaccinated person a booster!!
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Which polio vaccine produces a secretory Ab that prevents the initiation of infection?
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Sabin vaccine (oral, live, attenuated)
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Describe the polio vaccine that we currently use:
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Salk, inactivated polioviruses of all three serotypes. It is given IM and does not produce the duodenal IgA like Sabin.
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Are there any effective anti-viral agents against poliovirus?
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NO!
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Is it better to get Polio when you are young or old?
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Young, greater chance at getting paralytic poliomyelitis when you are old.
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What disease does Coxsackie Virus A cause? Describe?
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Hand-foot-and-mouth, common childhood illness, produces a short-lived (7-10d) fever and blisters in mouth/palms/soles. Can also cause conjunctivitis.
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Treatment for Coxsackie A? MOA?
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Pleconoril; binds to virion and changes it shape (so virus can attach to cell receptor an uncoat), blocking production of infectious progeny virus particles.
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Ways to test for all picornovirea/enteroviruses
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P: rectal/throat swab
E: enterovirus: culture CSF R: rhinov: clinical C: coxackie: culture CSF H: Hep A: serology for HAV particles |
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What drug is for all enteroviruses (HepA, Rotavirus, and Norwalk) and Coxsackie A
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Pleconaril: binds to and changes virion so it can't attach to the receptor.
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What presents like Coxsackie B?
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Echovirus; asymptomatic meningitis (just like a bad Coxsackie B/also A can) but it presents with GI symptoms.
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What are three enteroviruses discussed in lecture?
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1. Norwalk (+ssRNA)
2. Rotavirus (dsRNA, reoviridae) 3. Hepatitis A (+ssRNA) |
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How do you detect Hep A in body?
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Do serology to look for anti-HAV IgM in serum.
Also, HAV particles/antigens are present via immunoassay in the feces. |
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CASE:
Patient with HepA: what are their lab findings? |
Hypokalemia: from anorexia
Increase BUN: volume depletion Jaundice |
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What four viruses cause diarrhea?
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Rotavirus (dsRNA)
Norwalk (+ssRNA) Adenovirus (DNA, no envelop) Coronavirus |
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How does Rotavirus cause fever, and yellow diarrhea?
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It encodes a viral enterotoxin, NSP4. This mobilizes Ca causing Ca to be released from the intestinal stores with causes hypermobility. At the same time there is openning of Cl channels.
This infection is restricted to the villus epithelium of th SI. |
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Is there life long immunity for the rotavirus?
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There is a production of secretory IgA Ab that are very protective and probably induce life long immunity but 4 serotypes exist.
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Describe the RotaTeq vaccine:
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RotaTeq:
A live attenuated virus vaccine that is made by placing the genes encoding the human rotavirus capsid proteins of different serotypes into a bovine rotavirus. There is a risk of intussusption. Should be given in 3 doses, spaced 2 months apart. |
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What type of viruses are Norwalk viruses?
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(+)RNA, non-enveloped, in Calicivirus family
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What is the treatment for the Norwalk virus?
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Suppuritive care
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How many serotypes are their of the Norwalk virus?
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Many!
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How do you test for Norwalk virus?
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Can get ELISA but often just use clinical assessment
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SG:
20yo college student with nausea and vomiting/diarrhea has low grade fever, malaise, muscle aches. After 2d felt better, but roomates got sick 2 wks later. What is it? Test? |
Norwalk virus, test= clinical
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Study questions:
How do serum IgG antibodies protect us from disease caused by enteroviruses? |
ask?
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SQ
How do you detect infection with Hep A? |
From lecture:
Acute infection = anti-HAV IgM is detected in the serum HAV particles and/or antigens are detectable in immunoassay of the feces. |
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SQ:
WHy is it important to determine if babies hospitalized are infected with rotavirus? |
Since such a large number of particles are excreted there is a high incidence of nosocomial transmission. Children must be put in isolation.
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Test Q:
Major characterisitcs of the entervirus group of viruses include all of the following except: a. fecal-oral route, b. acid stable virion, c. proteolytic processing of the viral polyprotein to yield capsid and nonstructural proteins, d. primary viremia leading to spread of virus to target tissues, e. majority of infections result in frank cases of disease. |
E. Screwy question
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Describe basics of all herpesviruses:
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DNA, linear, double stranded, enveloped
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List the 6 types of herpesviruses:
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1. Herpes simplex (1 and 2)
2. Cytomegalovirus 3. Epstein-Barr virus 4. Varicella-zoster virus 5. Human Herpes 6 (and 7) 6. Human Herpes 8 |
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Why are herpes viruses unique?
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They become latent in the body after primary infection, with the potential for reactivation after varying periods of time.
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Do most people have antibodies to Herpes viruses?
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Yes
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Are most herpesvirus diseases prolonged or self-limited?
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Self-limited (but can be life threatening in an immunocompromised patient)
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What specifically is unique about the herpesvirus genome?
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There are two regions, Unique-L and Unique-S, which are braced in by inverted repeated sequences.
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How do herpes get into cell?
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Its unknown - but we do know that the viral envelop induces cell membrane fusion.
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Describe the transcription of a Herpes virus:
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There is an early and late period.
The early period, has alpha genes expressed (code for phosphoproteins). The late period has beta genes expressed with code for DNA-binding proteins. Gamma genes are then coded for to make structural proteins. |
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In the latent infections, are their any virions being produced?
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NO
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Describe the primary infection, latent infection, and recurrent infection of HSimplex 1:
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Primary: cold sores, sore throat, rare encephalitis (less freq: genital infection)
Latent: asymptomatic (viral DNA resides in the trigeminal nerve ganglion) Recurrent infection: virus replicates and travels down sensory nerve fibers around nose and mouth. Symptoms are usually milder |
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Describe the primary infection, latent infection, and recurrent infection of Herpes simplex 2:
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Primary: vesicular eruptions on genitalia (spread via sexual contact)
Latent: asympto; viral DNA resides in sensory cells of sacral ganglion. Recurrent: milder outbreak in same genital area |
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Describe the primary infection, latent infection, and recurrent infection of Varicella Zoster:
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Primary: fever, malaise, vescile production
Asympto: viral DNA resides in doral root gangion Recurrent: virus goes down sensory nerve fiber and infects epithelial cells inundated by fiber. Unilateral, painful, and systemic (in immunocomp) |
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What Herpesvirus infection can also cause blindness?
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Herpes simplex 1
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What happens if a neonate is exposed to the herpesvirus?
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A devastating disease that is often fatal.
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Does herpesvirus cross the placenta?
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YES
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What is the most common cause of fatal sporadic encephalitis in the US?
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Herpes simplex virus (though rare) - mortality is 70%
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What is the reactivation rate of HSV in patients receiveing transplants?
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85%
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What other side effect of HSV can immunosuppressed patients die of?
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HSV pneumonia
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Describe ACYCLOVIR:
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Used to treat Herpes Simplex I and II and Varicella Zoster:
Acts against viruses that encode Thymidine Kinase. Thymidine kinase activates the acyclovir (phosphorylation) and host cells do the same (2P). This Phos-Acycylovir blocks guanine triP this causes termination of the growing viral DNA chain. => No leading or lagging strands will be synthesized (vs. TZP/US = no DNA synthase since it inhibits helicase-primase complex) since Acyclovir does not have a 3'hydroxyl group to add on to as guanosine does. |
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Why does ACYCLOVIR not effect nL, non-infected cells?
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No phos occurs from uninfected cells so there is no active drug to inhibit nL cellular DNA synthesis or to cause toxicity.
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VIP
What mutations of Herpes viruses can generated ACV resistant strains? |
Mutations in:
1. Viral TK - drug is not phosphorylated 2. Viral polymerase - polymerase no longer binds to drug. |
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What drug prevents reoccurrance of HSV?
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Acyclovir
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Describe the contagious period of varicella?
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Contagious period PRECEEDS fever and rash on head/trunk
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Is varicella (chicken pox) sytemic?
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YES, there is a generalized vescicular rash.
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What type of varicella vaccine is there?
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Live, attenuated (gives 75-85% protection)
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What is the mneumonic for the Epstein-Barr virus:
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"Free drinks for people with African Burkitt's Lymphoma and Nasopharyngeal CA" at Epstein's Bar.
Try our "Oral Hairy Leukoplasia". No gay people allowed, only heterophile Ab's can come in. |
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What is the clinical presentation of EBV?
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Sore throat, fever, lymphadenopathy (90%), and splenomegaly.
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Amphicillin causes a rash in what patients?
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Ones with EBV
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What are three complications of EBV?
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1. ruptured spleen
2. neurologic complications 3. autoimmune hemolytic anemia |
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How is EBV transmitted?
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Through respiratory droplets and saliva.
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Lab diagnosis for EBV?
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Throat washing and a monospot test for HETEROPHILE ANTIBODIES.
Specific Viral Capsid Antigen (VCA) can also be done if early. Smear for atypical lymphocytes |
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If you are IgG (+) for EBV does that mean you are not producing it in your saliva anymore?
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No, you can be IgG (+) and still produce it in your saliva.
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What is the treatment of Epstein Barr virus?
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There is none.
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What is mechanism of invasion of EBV?
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EBV attaches to cells in the oropharynx and replicates there --> then bloodstream invasion occurs and B-lymph are infected and disseminate --> then t-cells kill/control B cell outgrowth and promote latency in B cells.
Tcells kill and control B-cell outgrowth and promote latency in B cells. |
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What is the mneumonic for cytomegalovirus?
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Cyto-metal-owl-virus (also: CMV is the STD of babies since it can be tranmitted sexually or orally/daycare)
Causes mental retardation in children (neonates). |
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Which is more serious for infants: EPV or CMV?
How do they get it? |
Cytomegalovirus - can get it during birth (and also intrauterine infections - less common)
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How is the cytomegalovirus transmitted?
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Blood/secretions (sexually/and kids that exchange saliva easily)
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What is TORCHES?
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Infections that can kill neonates/cross placenta:
Toxoplam, Rubella, Cytomegalovirus, |
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VIP
What disease causes pneumonitis in 20% of bone marrow transplant receipients? |
Cytomegalovirus
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What can CMV induce in the blood vessels?
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Re-stenosis
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What causes retinitis in AIDS patients most commonly?
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Cytomegalovirus
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Since CMV can also cause mononucleosis, how do you tell them apart?
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CMV has a special test: Shell Vial Assay test that can detect early antigens
Also, CMV has owl eye appearance. |
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What does Ganciclovir treat? How does it differ from Acyclovir?
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CMV-infected cells.
It only differs from ACV by one hydroxymethyl group. It DOES NOT encode TK but is phos'ed by CMV infected cells => inhibits DNA polymerases Side effect: causes bone marrow toxicity |
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What drug reduces the incidence of new cytomegalovirus in AIDS patients?
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Ganciclovir
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What is Rosella?
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Disease caused by Human Herpes Virus 6 and 7 that is a common disease in infancy
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VIP
What is the clinical presentation of Rosella? |
There is an abrupt rise in temperature followed in 2-4 days by a drop in temp + erythematous maculopapular rash that lasts for 1-2 day.
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What is the most common reason parents bring their infants in to the ER? Major problem?
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Rosella fever/rash
Major problem: no rapid diagnostics, some may develop seizures. |
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What cancer is linked to Human Herpes 8?
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Kaposi's sarcoma - red and raised lesions.
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What is the histological appearance of a Kaposi's sarcoma?
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Spindle-shaped tumor cells with neovascularization and inflammatory infiltrate.
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What resolves Kaposi's sarcomas?
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T-cells, which is why they can be reactivated during immunosuppression.
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What test predicts whether or not you will get Kaposi's sarcoma?
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Serologic testing for HHV 8; VIP: HIV + patients who are seropositive for HHV8 antigen have a 50% chance of developing KS.
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How does HHV 8 induce Kaposi's sarcoma?
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HHV 8 encodes several proteins similar to human proteins that promote cell growth and prevent apoptosis, trigger inflammation, and induce angiogeneisis.
HHV 8 induces IL-6, 8, and BCL-2 analogues. |
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What is the cure for Kaposi's sarcoma?
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There is no cure. But anti-retrovirals can cause regression of KS lesions
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Compare the parainfluenze virus, mumps, measles, RSV?
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Fusion protein = all positive
Hemagglutin = all postive except RSV Neuroaminidase = all positive except RSV and Measles Antigenic types: Para 4, Mumps 1, Measles 1, RSV 2. Immunity = short-lived for RSV and Para, and long-lived for Mumps and measles. |
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How does transmission of the mumps virus occur?
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ssRNA
respiratory droplets that infect the epithelial cells of the respiratory tract --> virus then spreads to tissues like salivary glands via blood (viremia). |
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What causes the symptom of swelling of the parotid glands in the mumps virus?
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Inflammatory response (which can also cause meningitis, encephalitis, pancreatitis, and oophoritis.
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How is mumps virus dx?
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virus can be isolated from the saliva, pharynx, and urine and grown in tissue culture cells
They show characteristic syncytial giant cells!!! Rapid dx can be made with EIA (anti-mumps virus antibodies) |
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When is the measle virus most infectious?
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2-3 days before the rash and fever appears!!
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What are the symptoms of measles?
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Fever and an exanthematous/maculopapulary rash.
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How is measles transmitted?
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Via respiratory droplets.
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What kind of virus is measles?
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(-)ssRNA, with envelop, its a paramyxovirus.
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What are three types of paramyxoviruses?
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Measles(-ssRNA, env), mumps (-ssRNA, env), rubella (+ssRNA, env)
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What virus causes pan-immunosuppression?
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Measles
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What is subacute schlerosing panencephalitis?
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A terrible side effect of the measles virus where the virus itself mutates and 2-10yrs after initial measles infection the mutant measles virus that got into the CNS starts to impact the body. This SSPE virus produces no M protein so there is no infectious virus to fight off (100% fatal)
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Population most affected with measles?
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Adopted children
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Is there a vaccine for measles? Will measles be erradicated?
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Yes, a live, attenuated vaccine. But measles will always be around since you can't vaccinate until 1 yr old.
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What type paramyxovirus causes pneumonia? What kind of pneumonia?
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Measles, giant-cell pneumonia
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How do you confirm dx of measles?
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clinical appearance of one of CCK= coryza, cough, conjunctivits, and Koplik's spots.
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Do you get life long immunity from the paramyxoviruses?
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(MMR) YES!
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Since rubella is considered a mild childhood illess what is the big deal?
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The problem is in pregnant women with rubella. This causes an acute infection (1st trimester) --> infects fetus --> can cause spontaneous abortions or "congenital rubella syndrome"
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What is congenital rubella syndrome?
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A syndrome causing deafness, cataracts, heart defects, organ damage, and mental retardation in the newborn.
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Discuss the symptoms of measles, mumps, and rubella.
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Mumps: parotidits, fever
Measles: systemic rash (from inflam response), fever, rare giant cell pneumonia, SSPE Rubella: URTI, rash, fever, congenital rubella sydroma |
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Why is kidney function important in patients with mumps?
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Because mump virus is excreted in the urine (can cause renal impairment)
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VIP
How do we test for Rubella? |
ELISA for increase in rubella IgG on sample from nasophaynx or urine.
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What do negative strand RNA viruses like Paramyxoviruses induce?
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They induce cell fusion!
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What are the only three paramyxoviruses that do get life long immunity?
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Human metapneumo, RSV, and Parainfluenza v
(measle, mumps, and rubella do) |
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What two viruses have NO VIREMIA?
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Respiratory syncytial virus and parainfluenza
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What is the most common cause of LRTI in infants and young children?
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Resp Syncytial virus
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Describe the pathogenesis of RSV?
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RSV is acquired through inhalation and is then confined to resp. epithelium (no viremia) --> the presence of RSV induces necrosis of bronchiolar epithelium, submucosa edema --> broncioles become occluded with mucus and cellular debris
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What will a chest x-ray look like from a child with RSV?
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There will be hyperinflation and airtrapping since the broncioles are occluded with mucus and cellular debris from the necrosis and edema of bronchiolar epithelium.
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What testing is used to look for RSV?
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Throat culture --> EIA and characteristic syncytia development.
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What is the peak season for RSV?
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Oct-April with peaks in January and Feburary.
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What is Palivizumab?
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A monoclonal Ab directed against RSV given to high risk infants.
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What is the anti-viral therapy available for RSV?
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Ribavirin (nucleoside analog) that inhibits viral replication (expensive!)
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Does RSV have HA or NA glycoproteins?
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NO!
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VIP VIP
What is the characteristic micrscopic appearance of RSV in tissue culture? |
Pattern on syncytia that results from the amalgamation of cells with loss of cell borders forming multinucleated cells.
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Is there a vaccine for RSV?
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No, there was but it made it worse!
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Describe the presentation of Human Metapneumovirus? Why can this be confusing?
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Presentation is same as HPV: asymp, cold sympt, sore throat, brochitis, etc.
Mistaken for RSV (cultures will be neg) |
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How can you tell RSV and Human metapneumovirus appart?
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RT-PCR!
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Two common causes of otitis media?
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Human metapneumovirus
Respiratory synctial virus |
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What causes CROUP?
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Parainfluenza virus
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What is a characteristic of CROUP?
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Children barking like seals
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Does parainfluenza cause an URTI or LRTI?
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Both, URTI is more common but LRTI is more dangerous.
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Are there any antivirals or vaccines for Parainfluenza?
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NO
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VIP
Why are Fusion (F) glycoproteins so important to all paramyxovirdae viruses? |
F proteins mediates syncytia formation which is the primary characterisitic of paramyxoviruses infections.
It is very important because it induces fusion, allowing virus to enter cell and make synctia for cell lysis. |
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What does the hemaggluttinin-neuroaminidase (HN) glycoprotein do? Which paramyxovirus does not have it?
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HN aggultinated erythrocytes and cleaves neuraminic (sialic) acid from glycoproteins.
Measles does not have neuraminidase RSV does not have either of them. |
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What do P and L proteins together form?
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RNA-dependant-RNA polymerase that is assoicated with the nucleocapsid of (-)RNA viruses.
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What virus other than Parainfluenza can cause CROUP?
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Coronavirus
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