Viruses Flashcards
Live Vaccines
Smallpox Yellow Fever Chickenpox Sabin's polio MMR Influenza (intranasal)
Killed Vaccine
Rabies
Influenza (injected)
Salk polio
HAV
Positive-strand RNA viruses
Retrovirus Togavirus Falvivirus Coronavirus Hepevirus Calicivirus Picornavirus
Naked viral genome infectivity
all dsDNA (except pox and HBV) (+) strand ssRNA
Viral replication - DNA viruses
all in nucleus (except pox)
Viral replication - RNA viruses
all in cytoplasm (expect influenza and retro)
Naked viruses
Papillomavirus Adenovirus Picornavirus Polyomavirus Calcivirus Parvovirus Reovirus Hepevirus
HSV-1
enveloped, dsDNA and linear
gingivostomatitis, keratoconjunctivitis, temporal lobe encephalities (most common cause in US); herpes labialis
latent in trigeminal ganglia
Transmission: respiratory secretions, saliva
HSV-2
enveloped, dsDNA and linear
herpes genitalis, neonatal herpes
latent in sacral ganglia
Transmission: sexual contact, perinatal
VZV
enveloped, dsDNA and linear
chickenpox, shingles, encephalitis, pneumonia
latent in dorsal root or trigeminal ganglia
Transmission: respiratory secretions
EBV
enveloped, dsDNA and linear
infectious mono-
infects B cells –> fever, HSM, pharyngitis, and lymphadenopathy (posterior cervical nodes)
Peak incidence - 15-20 years
Atypical lymphocytes = cytotoxic T cells
Burkitt’s/Hodgkin’s lymphoma, nasopharyngeal carcinoma
latent in B cells
Transmission: respiratory secretions, saliva
CMV
enveloped, dsDNA and linear
congenital infection, mono (negative monospot), pneumonia, retinitis
“owl’s eye” inclusions
latent in mononuclear cells
Transmission: congenital, transfusion, sexual contact, saliva, urine, transplant
HHV-6
enveloped, dsDNA and linear
Roseola: high fevers for several days that can cause seizures, followed by diffuse macular rash
HHV-8
enveloped, dsDNA and linear
Kaposi’s sarcoma (HIV patients)
Transmission: sexual contact
Hepadnavirus
enveloped, dsDNA and partial circular
HBV -
acute or chronic hepatitis
vaccine available (contains surface antigen)
has reverse transcriptase
Transmission: parenteral, sexual, maternal-fetal; has carrier state
long incubation (months); increased risk of HCC (integrates into host genome –> oncogene)
Adenovirus
naked dsDNA and linear
febrile pharyngitis - sore throat; acute hemorrhagic cystitis
pneumonia
conjuncitivitis (“pink eye”)
Parvovirus
naked ssDNA and linear (-) (smallest)
B19-
aplastic crisis in sickle cell
“slapped cheeks” rash in children - erythema infectiosum (fifth disease)
RBC destruction in fetus –> hydrops fetalis and death
pure RBC aplasia and RA-like symptoms in adults
Papillomavirus
naked, dsDNA and circular
HPV- warts (1, 2, 6, 11) CIN cervical cancer (16, 18, 31, 33) vaccine available
Polyomavirus
naked, dsDNA and circular
JC virus - progressive multifocal leukoencephalopathy in HIV
BK virus - transplant patients, commonly targets kidneys
Poxvirus
enveloped, dsDNA and linear (largest)
smallpox, although eradicated, could beused in germ warfare
Vaccinia - cow pox (“milkmaid’s blisters”)
Molluscum contagiosum - flesh colored dome lesion with central dimple
Reovirus
naked, dsRNA linear (10-12 segments), icosahedral
coltivirus - Colorado tick fever
rotavirus - #1 cause of fatal diarrhea in children
- acute diarrhea in US during winter, especially in daycares
- villous destruction with atrophy leads to decreased absorption of Na and loss of K
CDC recommends routine vaccination of all infants
Picornaviruses
naked, ssRNA (+) linear, icosahedral
PERCH
poliovirus
echovirus - aseptic meningitis
rhinovirus - common cold (acid labile - no GI infection)
coxsackievirus - aseptic meningitis; herpangina (mouth blisters, fever); hand, foot, and mouth disease; myocarditis
HAV - acute viral hepatitis
RNA is tranlated into 1 large polypeptide that is cleaved by proteases into functional viral proteins
all expect rhinovirus and HAV cause aseptic meningitis
all expect rhinovirus have fecal-oral transmission
Hepevirus
naked, ssRNA (+) linear, icosahedral
HEV-
Transmission - fecal-oral, especially with waterborne epimedics
no carrier state, short incubation period, no increased risk for HCC
high mortality in pregnant women
Caliciviruses
naked, ssRNA (+) linear, icosahedral
norovirus - viral gastroenteritis
Flaviviruses
enveloped, ssRNA (+) linear, icosahedral
HCV Yellow fever Dengue St. Louis encephalitis West Nile virus
Yellow fever
enveloped, ssRNA (+) linear, icosahedral
transmitted by Aedes mosquitoes (monkey and human reservoirs)
Symptoms: high fever, black vomitus, and jaundice
HAV
naked, ssRNA (+) linear, icosahedral
Transmission: fecal-oral
no carrier state; short incubation; no increased risk for HCC
usually asymptomatic, acute, alone (no carriers)
HCV
enveloped, ssRNA (+) linear, icosahedral
Transmission: primarily blood, IVDU, post-transfusion
carrier state, long incubation
increases risk for HCC (chronic inflammation)
chronic, cirrhosis, carcinoma, carrier
Arboviruses
coltivirus yellow fever dengue St. Louis encephalitis West Nile virus Eastern equine encephalitis Western equine encephalitis
Rubella
togavirus
enveloped, ssRNA (+) linear, icosahedral
German measles (3 day)
fever, postauricular adenopathy, lymphadenopathy, arthralgias
fine truncal rash that starts at head and moves down
mild disease in children, but serious congenital infection
Retrovirus
enveloped, ssRNA (+) linear,
HTLV (icosahedral) - T-cell leukemia
HIV (complex and conical) - AIDS
Influenza
orthomyxovirus
enveloped, ssRNA (-) linear (8 segments), helical
hemagglutinin - promotes viral entry
neuraminidase - promotes progeny virion release
patients at risk for bacterial superinfection (S. pneumoniae, S. areus, H. influenzae)
Paramyxoviruses
enveloped, ssRNA (-) linear, helical
Parainfluenza - croup
RSV - bronchiolitis in babies; Rx - ribavirin
Measles, Mumps
contain surface F (fusion) protein, causes respiratory epithelial cells to fuse and form multinucleated cells
Palivizumab (antibody against F protein) prevents pneumonia caused by RSV infection in premature infants
Measles
paramyxovirus
enveloped, ssRNA (-) linear, helical
Characteristics: Koplik spots (red spots with blue-white center on buccal mucosa) and descending maculopapular rash
rash appears last - spreads from head to toe (includes hands and feet)
Sequelae: SSPE (years later), encephalitis (1:2000), giant cell pneumonia (rarely, in immunosuppressed)
3 C’s: cough, coryza, conjunctivitis
Mumps
paramyxovirus
enveloped, ssRNA (-) linear, helical
Symptoms: parotitis, orchitis, aseptic meningitis
can cause sterility (especially after puberty)
Rabies
rhabdoviruses
enveloped, ssRNA (-) linear, helical
bullet-shaped virus
Negri bodies are characteristic cytoplasmic inclusions in neurons (commonly in Purkinje cells of cerebellum)
long incubation period (weeks to months) before symptoms onset
Progression: fever, malaise –> agitation, photophobia, hydrophobia –> paralysis, coma –> death
most commonly from bat, raccoon, and skunk than dog bites
Postexposure treatment: would cleansing and vaccination +/- rabies immune globulin
HIV
enveloped, ssRNA (+) linear,
diploid genome (2 molecules of RNA)
3 structural proteins: env (gp120 and gp41) ---formed from cleavage of gp160 to form envelope proteins ---gp120 - attachment to host CD4 T cell ---gp41 - fusion and entry
gag (p24) - capsid protein
pol - RT (dsDNA from RNA), aspartate protease, integrase
virus binds CCR5 (early) or CXCR4 (late) co-receptor and CD4 on T cells; CD4 and CCR5 on macrophages
