Term
For RNA viruses, generalize and give exceptions for;
-Strandedness
-Enzymes in capsule
-Envelope
-Segmented
-Replication site |
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Definition
Strandedness; all are ssRNA, except *Reovirus
Enzymes in capsule; all -RNA have RdRp, also;
-Reovirus (dsRNA)
-Retrovirus (reverse transcriptase)
Envelope; all are enveloped except;
-Picornavirus
-Calicivirus & Hepevirus
-Reovirus
Segmented; only ones are;
-Reovirus (ds)
-Orthomyxovirus (neg)
-Bunyavirus (neg)
-Arenavirus (ambi)
(ROBA sounds like robot, pieces)
Replication site; almost all in the cytoplasm
-Retroviruses us the nucleus
-Influenza (orthomyxovirus) can also use the nucleus
-To make things a bit easier, remember reovirus is an exception to almost every rule; it is dsRNA, non-enveloped, segmented, and carries a polymerase (not sure where it replicates) |
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Term
| What are the positive sense RNA viruses? |
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Definition
-Calicivirus
-Hepevirus
-Picornavirus
-Flavivirus
-Togavirus
-Coronavirus
-Retrovirus
-Mnemonic; CALL PICO and FLo TO COme Rightaway
-(hepe is grouped with calici) |
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Term
What can we say about +RNA viruses in terms of;
-Segmentation
-Capsule polymerase
-Replication site |
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Definition
-All are unsegmented linear +ssRNA, have no capsule polymerase, and replicate in the cytoplasm... except *retroviruses
-Retroviruses are diploid linear +ssRNA, have capsule reverse transcriptase, and replicate in the nucleus |
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Term
| What about envelope and shape for +RNA viruses? |
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Definition
All have an envelope except the first three;
-Calicivirus, hepevirus, and picornavirus
They are all icosahedral except;
-Coronavirus (helical), and retroviruses (icosahedral, but also truncated or conical) |
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Term
| What are the major viruses in each family? (use the chart on page 399 of pdf) |
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Definition
| -Remember the "PEE Co Rn A" mnemonic |
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Term
| What is the first thing +RNA do when it get's in the cell? |
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Definition
| -The +RNA is the same as mRNA, so it starts off immediately with translation (to make RdRp) |
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Term
| What is against the norm for caliciviruses? |
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Definition
-They are naked
-Means that they are transmitted by the fecal-oral route (contaminated food and water) |
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Term
| What is the medically important calicivirus? What is its reservoir and transmission? |
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Definition
-Norwalk virus (norovirus)
-GI tract is reservoir and transmission is fecal-oral
-Very common on cruise ships |
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Term
| What is the disease caused by norwalk virus? How do we treat it? |
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Definition
Acute gastroenteritis;
-**The most common cause of gastroenteritis in the US**
-Get nausea, vomiting, watery diarrhea (no blood or pus)
-We usually don't treat it |
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Term
| How do we differentiate this norwalk from rotavirus? |
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Definition
-Rotavirus is more in infants
-"If you can walk, it's norwalk" |
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Term
| What are the clinically important Hepeviruses? What is important about it? |
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Definition
-Hep E (HepE-viruses)
-Has high mortality in pregnant patients
-Also, remember, this is one of the naked ones
-See hep cards |
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Term
| What are the members of the picornaviruses? |
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Definition
-Polio
-ECHO
-Enteroviruses (group containing polio, coxsckie, & ECHO)
-Rhino
-Coxsackie
-Hepatitis A
Mnemonic; PEE Co Rn A |
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Term
| What is weird about picornoviruses? SIze? Peak incidence? |
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Definition
-They are the last of the *naked +RNAs
-Call Pico (because he's naked lol)
-Rem, hepeviruses are also naked, but not in mnemonic
-Also, it is the *smallest of the RNA viruses, and around the size of parvovirus (the smallest DNA)
-Pico(small)-RNA-viruses
-These are more common in the *summer and fall |
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Term
| Which ones were the enteroviruses again? What is odd about them? Who are they more common in? |
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Definition
-Polio virus
-Coxsackie virus A & B
-Echoviruses
-They are transmitted fecal-oral, but do not cause diarrhea**
-More common in children (they are "pico" lol) |
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Term
| What is odd about Rhinoviruses? |
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Definition
-They are naked, as all picornaviruses are, but are not stable in the *acid of the stomach
-Also, they grow best at *cooler temps of about *33C; this is why it causes head colds, and why chicken soup helps |
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Term
| For all the members of picornaviridae, give the transmission, pathogenesis, diseases, diagnosis, and treatment? (See the table on 403 for answers) |
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Definition
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Term
| What is weird about flaviviruses? |
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Definition
| -Nothing, they are a completely typical family of +ssRNA, which again, means; linear, non-segmented, no polymerase in the capsule, enveloped, icosahedral, and replication in the cytoplasm |
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Term
| What are the members of flaviviruses? How are they transmitted? |
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Definition
-Yellow fever
-Dengue
-St. Louis encephalitis
-Hep C
-West Nile virus
-They are all arboviruses, except for Hep C (rem hep C as the odd one out by C for color, and flavi means yellow) |
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Term
| Give the host, disease, and diagnosis for the different members of flaviviridae? Which have vaccines? (See faviviruses table on 404) |
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Definition
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Term
| What is the most common viral cause of encephalitis? |
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Definition
-HSV-1
-Have to consider this with SLE and WNV
-SLE and WNV are both spread by mosquitoes, however they are difficult to tell apart in a question as they are basically the same |
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Term
| What's weird about the togaviruses? |
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Definition
-Nothing, they are typical +ssRNA
-Also, they are somewhat special as some are arboviruses (rem. toga, flavi, and bunya) |
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Term
| What are the important togaviruses? Give all the info also (see chart on 405) |
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Definition
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Term
| What is weird about coronaviruses? |
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Definition
-It is helical
-Other than that it's got the normal linear +ssRNA with an envelope, and multiplication in the plasma
-Think of a twisted lemon peel in a corona lol |
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Term
| What are the viruses under the coronavirus family? And what do they cause (no table)? |
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Definition
Coronavirus;
-Second most common cause of the common cold
-More in winter/spring (Rhino is summer/fall)
SARS-CoV
-Severe acute respiratory distress syndrome |
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Term
For SARS, give;
-Reservoir
-Transmission
-Desease presentation
-Diagnosis
-Treatment |
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Definition
-Reservoir; birds and small mammals (civet cats)
-Transmission; respiratory
-Desease presentation; atypical pneumonia and flu-like
-Diagnosis; symptoms plus history of travel to endemic area (China or Toronto), also can detect antibodies
-Treatment; supportive |
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Term
| What is weird about the retroviruses? What does it's genome look like? What is it's shape? |
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Definition
-Their replication strategy is not the same as the other +ssRNA viruses which leads to a few important differences;
-RdDp (*reverse transcriptase) in the capsule
-Multiplication takes place in the nucleus
-Also, they are unsegmented, but **diploid
-The shape of the capsid can be icosahedral, but the most important one (HIV) has a *truncated cone shape (top is chopped off); called a type D retrovirus |
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Term
| What are the important retrovirus examples? |
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Definition
Human T-cell leukemia/T-lymphotropic virus
-Seen more in Japan and Caribbean
-Referred to as an oncovirus
HIV |
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Term
| What is the major protein we use to identify HIV early on? What are the other two? |
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Definition
-**p24; a capsid protein (can identify right after infection)
-p7p9 & p17 are also there, but less important |
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Term
| What enzymes does HIV have with it (3)? |
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Definition
-Reverse transcriptase; extremely error prone (genetic drift)
-Integrase; integrates genome into host DNA
-Protease; for cutting viral proteins to size |
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Term
| What are the envelope proteins of HIV? What do they bind (include host coreceptors)? |
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Definition
-gp120; binds CD4 & CCR5(mac) or CXCR4(T cells)
-gp41; for viral fusion to host cell |
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Term
| What are some key regulatory genes of HIV and what do their products do? |
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Definition
-**Nef; downregulates MHC I expression (responsible for virulence and required for progression to AIDS)
-Tat; transactivator (upregulates transcription)
-LTR; long terminal repeats (helps with integration)
-Rev; regulatory (increases transport of products to cyt) |
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Term
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Definition
-It uses gp120 to attach to CD4 with CXCR4 (T cells) as a coreceptor (uses CCR5 on macs earlier in infection)
-The macrophages serve mostly as a reservoir |
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Term
| Where does HIV make it's mRNA and progeny genomes? How does it leave the host? |
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Definition
-It makes the mRNA (cut genome) and genome (uncut) in the nucleus from the provirus (integrated viral DNA), and then ships it to the cytoplasm for translation
-It buds off the pm (as do most enveloped viruses) |
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Term
| What makes someone immune? |
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Definition
-They have a **CCR5 mutation so HIV can't use macrophages in the beginning and also have no reservoir
-Have to be homozygous; only slowed if hetero
-Long term survivors aren't immune, but the HIV may have a *Nef mutation |
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Term
| At what CD4 level do we start prophylaxis for the infections that come along in HIV? |
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Definition
| -Between 200 and 50 CD4 we start prophylaxis for different things |
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Term
| What are the screening and confirmation test for HIV? What do we use PCR for? What is the early marker? Where does flow cytometry come in? |
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Definition
-ELISA screens, *western blot confirms
-We can use PCR to determine viral load (esp. in infants)
-p24 protein, and antibodies come up pretty early as well
-We use flow cytometry to check CD4 to CD8 level (should have double CD4s) |
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Term
| What are the RT inhibitor drugs? The protease inhibitor drugs? What is HAART? What is a problem with these? |
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Definition
-RT inhibitors end in "-ine"; (nucleoside analogs usually)
-Protease inhibitors end in "inavir"
-Highly Active Anti-Retroviral Therapy; combines both above
-HIV gets resistant to these treatment methods
-HAART cocktail decreases this effect and is the current standard treatment |
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Term
| What are the other things we can target to treat HIV? What about resistance? |
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Definition
Fusion protein inhibitors; Fuzeon, enfuvirtide
CCR5 antagonist; Maraviroc
Integrase inhibitor; Raltegravir
-No resistance has been seen yet
-These are all newer and not standard treatment; so names aren't as important as target for now (I think lol) |
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