RNA viruses Flashcards
Reoviruses
No ENV, DS linear, 10-12 segments,
Isocahedral(double)
Coltivirus-Colorado tick fever
Rotavirus-#1 cause of fatal diarrhea in children
Picornavirus
No ENV, ss + linear, icosahedrral
Polio Echovirus: aseptic meningitis Rhinovirus: common Coxsackies: aspetic meningitis, herpangina (mouth blisters, fever), hand, food and mouth disease, myocarditis HAV: acute viral hepatitis
PERCH
Hepevirus
NO ENV, ss + linear, icosahedral
HEV
Calcifivirus
NO EVN, ss + linear, icosahedral
Norovirus-viral gastritis
Flavivirus
ENV, ss + linear, icosahedral HCV, Yellow fever Dengue, St. Louis encephalitis West Nile virus
Togavirus
ENV, ss + linear, icosahedral
Rubella
Eastern equine encephalitis
Western quine encephalitis
Retrovirus
ENV, ss + linear, icosahedral (HTLV) vs complex and conical (HIV)
Have RT
HTLV- T cell leukemia
HIV-AIDS
Coronavirus
ENV, ss + linear, helica
Common cold and SARS
Orthomyxoviruses
ENV, ss - linear, helical, 8 segments
Influenza
Paramyxoviruses
ENV, ss - linear, helical, nonsegmented
Parainfluenza = CROUP
RSV= bronchiolitis in babies, treat with ribavirin
Measles
Mumps
Rhabdovirus
ENV, ss - linear, helical
Rabies
Filovirus
ENV, ss - linear, helical
Ebola/Marburg hemorrhagic fever
often FATAL
Arenaviruses
ENV, ss - linear, helical, 2 segments
LCMV-lymphocytic choriomeningitis virus
Lassa fever encephalitis: spread by mice
Bunyaviruses
ENV, ss - linear, helical, 3 segments (vs. Arena with 2)
California encephalitis
Sandfly/Rift valley fevers
Crimean-Congo hemorrhagic fever
Hantavirus-hemorrhagic fever, pneumonia
Delta virus
ENV, ss - linear, Uncertain
HDV is defective virus that requires HBV.
Negative stranded viruses
Must transcribe negative to positive
Must bring its own RNA dependent RNA pol
Arenavirus, buynavirus, paramyxo, orthomyxo, filovirus, and rhabdovirus
“Always Bring Polymerase Or Fail Replication”
Segmented viruses
All are RNA viruses
Bunya, orthomyxo, arena, and reoviruses
“BOAR segments”
Picornavirus
PERCH
RNA translated into a large polypeptide leaved by proteases.
Can cause aseptic viral meningitis (except rhino and HAV)
All are entero (fecal oral) except rhinovirus
Rhinovirus
Picnoa
Non enveloped RNA
Common cause of cold, >100 serotypes
Acid labile, therfore does not infect the GI
Yellow fever
Flavivirus and arbovirus
Transmitted by Aedes mosquitos
Monkey and human reservoir
Symptoms: high fever, black vomitus, and jaundice
Flavi: means yellow and jaundice
Rotavirus
Most important global cause of infantile GI
Segmented RNA, reovirus
Major cause of acute diarrhea in the US during winter esp in dare care centers
Villous destruction with atrophy leads to decreased absorption of Na and loss of K+
Influenza
Enveloped, negative single stranded with 8 segments
HA: promotes viral entry
NA: promotes viral eggress
Patients at risk for fatal bacterial superinfection
Shift: assortment of genomes, causes PANDEMIC
Drift: minor changes, causes EPIDEMIC
“Sudden shifts are more deadly than graDual Drift”
Rubella virus
Togavirus
Cause rubella, one know as German measles (3day)
Fever, posauricular adenopathy, LAD, arthralgia, fine TRUNKAL rash that starts at HAND move moves DOWN
(Vs. Scarlett fever with face sparing)
“Rub-ear=postauricular, rubella”
Causes mild disease in children but serious congenital disease.
Paramyxoviruses
Paramyxovirus cause disease in children
Parainfluenza: croup: bark like cough
RSV: bronchiolitis, pneumonia
Mumps and measles
All contain surFace protein F (fusion) protein, which causes respiatory epithelial cells to fuse and form multinucleated cells
Palivizumab (antibody against F protein) prevents pneumonia caused by RSV in premature infants.
Measles virus
Paramyxo
Koplit spot and descending maculopapular rash
Possible sequelae: SSPE (subacute sclerosing panecephalitis, occuring years later), encephalitis (1:2000), and giant cell pneumonia (rarely, in immunosuppressed)
Rash presents LAST and spreads from head to TOE
Includes HANDS and FEET (vs. truncal rash in rubella)
Do not confuse with roseola (caused by HHV 6)
“Three C’s of Measles: Cough, coryza, conjuctivitis”
Mumps virus
Also paramyxo
Parotitis, Orchitis and aseptic Meningitis (POM)
can cause sterility, especially after puberty.
Rabies
Bullet shaped, Negri bodies
Commonly found in Purkinjee cells of cerebellum
Rabies have LONG incubation period (wks to months)
Postexposure treatment is wound cleansing and vaccination with rabies immune globulin
Travel to the CNS by retrograde fashion.
Progression of disease:
fever, malaise => agitation, photophobia, hydrophobia => paralysis, coma => death
More commonly from bat, raccoon, and skunk bites than from dog bites in the US.
HEV
RNA hepevirus (no env, ss+linear icosahedral) Fecal oral (like HA), esp with waterborne epidemics
No carriers, short incubation time
No HCC risk
High mortality in pregnant women
“enteric, expectant mother, and epidemic”
Viral hepatitis
Episodes of fver, jaundice, elevated ALT and AST
HAV/HEV are oral fecal
HBV: use its own DNA dependent DNA pol to make full strand dsDNA. Then the host RNA polymerase transcribes them.
Hepatitis markers
Anti HBc: antibody to HBcAg
= IgM=acute/recent infection, IgG=prior exposure or chronic infection.
HBeAg: a second different antigenic determinants in the HBV core. HBeAg indicates active viral replicaiton and thus high transmissibility
Anti HBe: antibody to E antigen, indicates low transmissiblity
Window period: no antigen, but anti HBe and anti HBc (IgM) and no anti HBs
Chronic with high infectivity: HBsAg, HBeAg and anti HBc (IgG), but no anti HBs
Chronic with low infectivity: HBsAg, anti HBe and anti HBc (IgG), but no anti HBs
HIV
Diploid genome (RNA), three structural proteins.
Env (gp120, gp41): fromed from cleavage of gp160 to form enveloped proteins
- gp120: attachment CD4 cells
- gp41: fusion protein
Gag(p24): capsid protein
Pol: RT, aspartate protease, integrase
Virus binds CCR5 (early), or CXCR4 (late coreceptors and CD4 on T cells; it only binds to CCR5 and CD4 on macrophages.
HIV diagnosis
ELISA: high sensitive, to rule out
Western: high specific, to rule in
PCR: viral load, to monitor drug efficacy
AID dx: <1.5
ELISA/Western: falsely negative in the first 2 months of HIV infectipn and falsely positive initially in babies born to infected mother (as anti gp120 crosses placental).
HIV time course
Four stages
Flu like, feeling fine, falling count, final crisis
CD4 < 200: AIDS.
During the latent phase, the virus replicates in the LN
