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BR-RNA viruses
5/31/06
| Question | Answer |
|---|---|
| Naked nucleic acids from what kind of strands are infectious? | dsDNA (except poxvirus & HBV) and (+)strand ssRNA (~mRNA) |
| Naked nucleic acids of which strands are not infectious? | (-)RNA viruses and dsRNA viruses |
| Name the Naked (nonenveloped) RNA viruses...naked CPR | Calcicivirus, Picornavirus, Reovirus |
| All enveloped viruses gain their envelopes from the plasma membrane when they exit the cell except... | herpesvirus, which acquires it from the nuclear membrane |
| All viruses are haploid (1 copy of RNA or DNA) except... | retroviruses, which have 2 identical ssRNA molecules (diploid) |
| All DNA viruses replicate in the nucleus except | poxvirus |
| All RNA viruses replicate in the cytoplasm except | retroviruses and influenza |
| What kind of immunity does a live attenuated vaccine induce? | humoral and cell-mediated; can be virulent (avoid in immunocompromised/their family) |
| Killed vaccines activate what type of immunity? | humoral; these are stable |
| What are the live attenuated vaccines? | MMR, Sabin polio, VZV, yellow fever, smallpox |
| What are the killed vaccines? | rabies, influenza, HAV, Salk polio |
| Which vaccine is recombinant? | HBV; HbsAg |
| Define recombination | exchange of genes btw 2 chromosomes by crossing over w/in regions of significant base sequence homology |
| Define reassortment | when viruses with segmented genomes (ex: influenza) exchange segments; high-frequency recombination; causes worldwide pandemics |
| Define complementation | when 1 of 2 viruses that infect a cell has a mutation that results in a nonfunctional protein. The nonmutated virus "complements" the mutated one by making a functional protein to serve both viruses |
| Define phenotypic mixing | genome of virus A can be coated w/surface ptns from virus B; Type B ptn coat determines the infectivity of the phenotypically mixed virus but the Progeny of type A infxn is encoded by A genome |
| DNA enveloped viruses | Herpesviruses (HSV type 1 & 2, VZV, CMV, EBV), HBV, smallpox |
| DNA nucleocapsid viruses | Papillomavirus, Adenovirus, Parvovirus |
| RNA enveloped viruses | Influenza, parainfluenza, RSV, MMR, rabies, HTLV, HIV |
| RNA nucleocapsid viruses | Enteroviruses (polio, coxsackie, echo, HAV), rhino, reo |
| Slow viral infections (exist in pt for years before manifesting as clinical dz) | Subacute Sclerosing Panencephalitis (measles sequelae), Progressive Multifocal Leukoencephalopathy (reactivated JC virus in AIDS pts) |
| Segmented viruses: BOAR | Bunyaviruses, Orthomyxoviruses (influenza; 8 segments of (-)stranded RNA...reassortment), Arenaviruses, Reoviruses; |
| PicoRNAviruses = small RNA viruses | polio, rhino, coxsackie, echo, HAV; RNA is translaged into 1 large polypeptide that is cleaved by proteases into fxnl viral ptns; can cause aseptic (viral) meningitis except rhino and HAV |
| Rhinovirus...has a runny nose | cause of common cold; cannot cause meningitis; nonenveloped; 100 serologic types |
| ROTAvirus (right out of anus) | most important global cause of infantile gastroenteritis!!; segmented dsRNA reovirus; acute diarrhea in US in winter |
| Paramyxoviruses | parainfluenza (croup), mumps, measles, RSV (bronchiolitis, pneumonia) in infants; all have 1 serotype except parainfluenza (has 4) and RSV (has 2) |
| Mumps is a paramyxovirus with | 1 serotype; it gives you bumps (parotitis), meningitis, & orchitis (testes); can cause sterility esp after puberty |
| Measles virus is a paramyxovirus that | causes measeles; Koplik (blue/gray) spots on buccal mucosa; SSPE, encephalitis, giant cell pneumonia; cough, coryza, conjunctivitis |
| Influenza viruses are | segmented enveloped ssRNA; Hemagglutinin +, Neuraminidase +; Pandemic; risk for bacterial superinfxn; rapid genetic changes (shift or drift) |
| Define Genetic Shift | reassortment of viral genome; ex: when human flu A recombines with swine flu A |
| Define Genetic Drift | minor changes based on random mutation |
| How do you protect against influenza? | killed vaccine which is reformulated each fall; offered to elderly, newborns, healthcare workers |
| Which drugs are used as prophylaxis for influenza A exposure? | Amantadine and Rimantadine |
| Which drugs are used as prophylaxis for influenza A and B exposure? | Zanamivir and Oseltamivier (neuraminidase inhibitors) |
| Rabies infection is characterized by | Negri bodies (inclusions in neurons); Retrograde migration in CNS thru axons; virus has a bullet-shaped capsid; Long (wks-3mo) Incubation; Fatal encephalitis w/seizures & hydrophobia; Bat/racoon/skunk bites in US; Tx = antiserum and vaccine |
| ARBOvirus are ARthopod-BOrne viruses including: | flavi, toga, bunyaviruses; mosquitos, ticks; Dengue fever (bone-break) and Yellow fever; variant in SE Asia is hemorrhagic shock syndrome |
| Yellow Fever is caused by | flavivirus; Aedes mosquito; Monkey and human reservoir; High fever, BLACK VOMITUS, jaundice; "Councilman bodies" in liver (acidophilic inclusions) |
| HSV-1 is acquired via .... and causes... | respiratory secretions or saliva; gingivostomatitis, keratoconjunctivitis, temporal loba encephalitis, herpes labialis |
| HSV-2 is acquired by... and causes ... | sexual, perinatal; herpes genitalis, neonatal herpes meningoencephalitis |
| VZV is acquired by ... and causes... | respiratory secretions; shingles, encephalitis, pneumonia |
| EBV is acquired by.... and causes... | respiratory secretions, saliva; infectious mononucleosis, Burkitt's lymphoma |
| CMV is acquired by... and causes... | congenital, transfusion, sex, saliva, urine, transplant; Congenital infxn (cutaneous bleed, deaf, CNS periventricular calcification, microsephaly), mononucleosis, pneumonia |
| What is the most common cause of intrauterine fetal viral infection? | CMV |
| HHV-8 is acquired by.... and causes ... | sex; Kaposi's sarcoma (HIV pts) |
| Facts about mononucleosis...cause...symptoms...incidence... | EBV (herpesvirus); fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (esp Post Auricular Nodes); 15-20yo "kissing dz" |
| Tests for EBV mononucleosis | Positive Monospot/heterophil Ab test (agglutinates sheep RBCs); atypical CD8 lymphocytes |
| Tzanck Test is performed by... | smearing an open skin vesicle to detect Multinucleated Giant Cells; used to assay for HSV-1, -2, or VZV |
| HIV genome | diploid; 2 RNA molecules; uses Reverse Transcriptase to make dsDNA which integrates with the host DNA |
| p24 | HIV rectangular nucleocapsid protein |
| gp41 and gp120 | HIV envelope proteins |
| Presumptive HIV diagnosis | ELISA (sensitive, high false + rate...this test rules out negatives) |
| Positive HIV ELISAs are confirmed with... | western blot (specific, high false-negative rate; rule in test) |
| HIV PCR/viral load tests | measures viral RNA in blood; allows Dr to monitor drug therapy by observing decrease in levels |
| ELISA and Western blot tests for HIV are often Falsely Negative during this time period: | 1-2 months following infection; they screen for antibodies to viral proteins |
| CCR5 mutation is a/w | 1% and 20% of caucasians who either have immunity (homozygous) or a slower course (heterozygous) when exposed to HIV |
| CXCR1 mutation is a/w | rapid progression to AIDS |
| Acute phase of HIV infection | 0-3 months; viral load is up in the middle causing flu-like symptoms |
| Latent phase of HIV infection | CD4 lymphos are stable, viral load is low, Abs produced against p24 and gp120; 2-3months - years |
| Immunodeficiency; AIDS phase of HIV infection | plummeting CD4 levels; decline in antibodies, rise in viral/p24Ag load |
| Bacterial opportunistic infections in AIDS | TB, Mycobacterium avium-intracellulare complex |
| Viral opportunistic infections in AIDS | HSV, VZV, CMV, PML (JC virus) |
| Fungal opportunistic infections in AIDS | Thrush (candida), cryptococcosis (meningitis), histoplasmosis, pneumocystis pneumonia |
| Protozoan opportunistic infections in AIDS | Toxoplasmosis, cryptosporidiosis |
| Prions | infectious proteins that do not have RNA or DNA ; encoded by cellular genes; Creutzfeld-Jakob (rapid progressive dementia), kuru; a/w Spongiform encephalopathy; beta-pleated sheets |
| Congenital HSV | acquired during delivery; vesicles, encephalitis, retinitis, or disseminated disease |
| Congenital Rubella | MR, heart abnormalities, blindness, encephalitis, motor abnormalities |
| Congenital Syphilis | death in utero; teeth, bone, CNS abnormality |
| Congenital Toxoplasmosis | severe if acquired during pregnancy; still birth, chorioretinitis, intracerebral calcifications, microcephaly |
Created by:
bscaryp