micro-virology

DNA enveloped viruses

Herpesviruses (HSV, VZV, CMV, EBV), HBV, smalpox virus

DNA nucleocapsid viruses

adenovirus
papillomaviruses
parvovirus

RNA enveloped viruses

Influenza
parainfluenza
RSV
measles
mumps
rubella
rabies
HTLV
HIV

RNA nucleocapsid viruses

Enteroviruses (polioviurs, coxsackievirus, echovirus, HAV)
rhinovirus
reovirus (rotavirus)

All DNA viruses are linear except

Papilloma and polyoma (circular, supercoiled)
hepadna (circular and incomplete)

Herpesviruses
'gon't get herpes in a CHEVrolet'

+envelope
dsDNA- linear
HSV-1 oral, keratoconjunctivitis
HSV-2 genital, lesions
VZV chickenpox, zoster, shingles
EBV mono, burkitt's lymphoma
CMV infection in immunosuppressed, esp transplant; congenital defects
HHV -6 roeola (exanthem subitum)
HHV-8 Kapo

Roseola

HHV-6 dx: transient rash - starts on neck, spreads to trunk and head but is gone w/ a day; preceded by a 3 day self limiting high fever; usually pt is < 2yo (febrile confvulsions rarely occur)

Hepadnavirus

enveloped
dsDNA-partial circular
HbV = acute or chornic hepatitis
vaccine available
contains reverse transcriptase even though it's not a retrovirus

Adenovirus

no envelope
dsDNA-linear
febrile pharagitis, sore throat
penumonia
conjunctivitis - 'pink eye'

Parvovirus

no envelope
dsDNA-linear (smalles DNA virus)
B19 virus = aplastic crises in sickle cell dx
'slapped cheeks' rash (erythema infectiosum (fifth disease)
hydrops fetalis

Papillomavirus

no envelope
dsDNA-circular
HPV-warts, CIN, cervical CA

Polyomavirus

no envelope
dsDNA-circular
JC - progressive multifocal leukoencephalopathy (PML) in HIV

Poxvirus

enveloped
dsDNA-linear (largest dna virus)
smallpox, althrough eradicated, could be used in germ warfare
vaccinia-cowpox (milkmaid's blisters'
molluscum contagiosum

Picornaviruses
(PERCH)

no envelope
ssRNA-linear
Poliovirus - polio-salk/sabin vaccines-IPV/OPV
Echovirus - aspetic meningitis
Rhinoviurs - 'common cold'
Coxsackievirus-aspetic meningitis, (cox A) herpangina-febrial pharygitis, hand, foot, and mouth disease, (Cox B) myocarditis

hand, foot and mouth disease

causes dy enterovirus - cox A
consists of high fever followed by sore throat and blisters on the top of the throat, palms and soles (rash may also cover the body)

Caliciviruses

no envelope
ssRNA-linear
HEV
norwalk virus - viral gastroenteritis

Reoviruses

no envelope
dsRNA-linear (10-12 segments)
*double icosahedral*
reovirus-colorado tick fever
rotavirus - #1 cause of fatal diarrhea in children

Colorado tick fever

*reovirus
Two phased febrile disease: fever, chills, headaches,pain behind the eyes, light sensitivity, muscle pain, generalized malaise abdominal pain, nausea, vomiting as well as a flat or pimply rash

Togaviruses

enveloped
ssRNA-linear
rubella (german measles)
eastern equine encephalitis
western equine encephalitis

Flavaviruses

enveloped
ssRnA-linear
HCV
Yellow fever
Dengue
st.louis encephalitis
west nile virus

what are arboviruses? Name them (paul bunyan wearing a toga w/ a mosiquito sucking is flavorful bd!)

viruses transmitted by arthropods:
Some flaviviruses (yellow fever, dengue, st.louis encephalitis, west nile)
Some togaviruses (east and western equine encephalitis)
some bunyaviruses (cali encephalitis and Cremean-congo hemorrhagic fever)

Retroviruses

enveloped
ssRNA-linear
have reverse transcriptase
HIV-aids
HTLV (human t-lymphotropic viruse)-tcell leukemia

Coronavirus

enveloped
ssRNA-linear
coronavirus = common cold and SARS

orthomyxoviruses

enveloped
ssRNA-linear (8 segments)
influenza virus

Paramyxoviruses (PRM)

enveloped
ssRNA-linear, nonsegmented
P: parainfluenza = croup
R: RSV - bronchiolitis in babies, rx = ribavirin
M: measles - rebeola
M: mumps

Rhabdoviruses

enveloped
ssRNA-linear
rabies

Filoviruses

enveloped
ssRNA-linear
ebola/marburg hemorrhagic fever -often fatal

ebola

*filovirus
early symptoms: high fever, headache, jt pain, abd pain, severe weakness, sore throat, n/v; later: bdy diarrhea, petechia from sclerotic arterioles, hypovolemia, tachy, organ failure

Arenaviruses

enveloped
ssRNA-circular
LCV - lymphocytic choriomeningitis
lassa fever encephalitis - spread by mice

Lassa Fever

*arenavirus
mainly found in Africa
Hemorrhagic fever w/ GI; Respiratory; cardiovascular involvement - quickly fatal if not treated

Bunyaviruses

enveloped
ssRNA-circular (3 segments)
California encphalitis
sandfly/rift valley fevers
crimean-congo hemorrhagic fever
Hantavirus - hemorrahgic fever, pneumonia

Deltavirus

enveloped
ssRNA-circular
Hepatitis D virus

Segmented viruses (BOAR)

Bunyaviruses {Hantav, enceph, hemorrhagic fever}
Orthomyxoviruses (influenza)
Arenaviruses {LCV}
reoviruses {rotavirus}

HSV-1

Gingivostomatitis (oral uclers); keratoconjunctivitis, temporal lobe encephalitis, herpes labialis
*tranmission: respiratory secretions, saliva

VZV

Shingles, encephalitis, pneumonia
*trans: respiratory secretions

EBV

infectious mono, Burkitt's lymphoma [t(8:14)]
*trans: respiratory secretions, saliva
*oral hairy leukoplakia in HIV

CMV

congential infection, mono (neg monospot, which is only + in ebv mono), pneumonia, path: owl's eye
*trans: congenital, transfusion, sex, saliva, urine, transplant

HHV-8

Kaposi's sarcoma (HIV pts)
*trans: sex
dx characteristics: hemorrhagic skin lesions are papular, +/- fungating, GI, respiratory involvement, hard palate lesions; rx: supportive and HAART shrinks & slows growth

Tzanck test

take a smear of opened skin vesicle - looks to detect multinucleated giant cells = HSV1, 2 and VZV. Infected cells also have intranuclear cowdry A inclusions
"Tzanch heavens I don't have herpes!"

Monospot test

heterophil Ab's detected by agglutination of sheep RBC's
*is postive for EBV mono, - in CMV mono*

Mono symptoms (4)

Mono associations

Fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (esp p.auricular nodes)

Hodgkin's and Burkitt's

Yellow fever

*flavivirus (arbovirus carried by aedes mosquitos)
*monkey or human reservoir
*high fever, blk vomitus, jaundice
*path: councilman bodies (acidopohilic inclusions) may be seen in liver

pathophys of rotavirus

*acute watery diarrhea in winter*
villous destruction w/ atrophy leads to decreaed absorption of Na+ & water

Rubella

*togavirus = ssRNA
3 days of measles, fever, lymphadenopathy, arthralgia, fine truncal rash; serious congenital disease

TORCH(s)

Toxoplasmosis
Other: VZV, parvo
Rubella
CMV
Herpes
(syphilis)

Genetic shift

Reassortment - rapid change of antigens via segment exchange b/w two different segments on different viruses
*could causes pandemic*

Genetid drift

antigenic drift - gradual change via random mutations w/in virus that changes the antigenic makeup
*drift in hemagglutinin (HA) and neuramidase (NA) of the orthomyxoviridae causes epidemics*

Rx of Influenza

Amantadine and rimantadine - useful for influ A, but resistance is high
Zanamivir and oseltamivir (neuraminidase inhibitors) useful for both A and B

Koplik spots

red spots w/ blue-white center on buccal mucosa, diagnostic for measles - show up 1-2 days before body rash

Measles: 3 C's and possible complications

Prodrome: Cough, Coryza (severe cold), Conjunctivitis/photophobia *rash spreads from head to toe, appears 2-3 days after prodrome onset*
SSPE (yrs later), giant cell pneumonia (immunosuppressed)

Mumps symptoms (POM)

*paramyxovirus
Parotitis
Orchitis (testes inflamm) - weary of sterility
Meningitis (aseptic)

Nigri bodies

characteristic cytoplasmic inclusions in neurons by rabies virus

Rabies virus - dx

ssRNA,Bullet-shaped capsid - travels retrograde up nn to CNS
dx: long incubation (wks-mo), fatal encephalitis, seizures, hydrophobia, hypersalivation, pharyngeal spasm
*trans: bat, racoon, skunk > dog

HAV

Asyptomatic (usually)
Acute - short incubation (3 wks)
Alone (no carriers
*fecal-oral*

HBV

Bd borne
*parenteral, sex, matenal-fetal routes
*long incubation - 3 mo
*hepadnaviruse has a DNA dependent DNA polymerase

HCV

*flavavirus
Chronic
Cirrhosis
CA
Carriers
Coke addicts
*trans: bd

HDV

*delta agent*
defective (req's HBsAg as its envelope
Dependent - on HBV for co-infection
*carriers

HEV

*RNA calicivirus
Enteric
Expectant mothers (high mortality)
Epidemics (water borne)

which HSV's predispose to chronic active hepatitis, cirrhosis, and hepatocellular Ca?

HBV and HCV

neuramindidase (NA) function

antigenic NZ produced by influenza viruses - cleaves neuraminic acid, which is a component of mucin - our respiratory defense barrier

Hemagglutinin (Ha)

antigenic protein of influnza viruses that attaches sialic acid R's present on surface of rbcs (causes heme agglutination when mixed w/ rbcs)

number one cause of pneumonia in youngins (<6 mo)

RSV

Human T-cell leukemia virus (HTLV-I)

*caribbean islands
Tcell leukemia
tropical spastic paraparesis
*retrovirus*

HIV genome

gag: group antigen - codes all major antigenic proteins
env: codes envelope proteins (pg120 and gp41)
pol: codes protease, integrase and reverse transcriptase

function of reverse transcriptase

synthesizes dsDNA from ssRNA (dsDNA then integrates into host genome)

CD4 < 50 increases risk to:

CMV retinitis and esophagitis
disseminated M.avium-intracellulare
cryptococcal meningoencephalitis

CD4 < 100 increases risk to:

candidal esophagitis
toxo
histo

mycobacterium avium-intracelulare (MAI) presentation

smoldering, wasting, fever, night sweats, weight loss, diarrhea, elevated LFTS

CMV - congenital dx

MR (most common viral form of MR), microcephaly, deafness, seizures, multiple other defects

Hantavirus

Bunyavirdae
presents w/ Respiratory distress (ARDS)/pneumonia
carried by rodents

Subsclerosing panencephalitis (SSPE)

rare complication of measles (presents yrs after acute dx resolves): personality changes, lethargy, odd behavior, myoclonic jerking, dementia, eventual flaccidity and rigidity... death at any stage

signs of congential rubella

deafness, cataracts, heart defects (PDA, PAS), MR

Signs of congenital CMV

petechial rash, intracranial calcifications, MR, hepatosplenomegaly, microcephaly, jaundice - but 90% asymp at birth

signs of congenital HIV

hepatosplenomegaly, neurologic abnormalities, frequent infections