Microbiology - Virology

shahenda's version from 2015-06-17 11:15


Question Answer
Recombinationexchange of genes b/t 2 chrom crossing over
Reassortmentvirsues with segmented genomes (e.g. flu) exchange segments
Complementation1 of 2 viruses that infect the cell has a mutation that reults in nonfn. protein - the non mutated virus "compliments" the mutated one by making a protein that works for both viruses
Phenotypic mixingsimultaneous infection of cell with 2 viruses. virus A genetic information coated by virus B surface proteins. Type A can infect cells that usually are infected by Type B, but future generations cannot b/c don't carry Type B genetic code for surface proteins.
Genetic Shiftreassortment of viral genome; segments undergo high-freq recombination
Genetic Driftminor (antigentic drift) changes based on random mutations
Which is worse - Genetic Drift or Shift?Sudden Shift is worse than graDual Drift


Question Answer
Live (attenuated) VaccinesSmallpox, Yellow Fever, Chickenpox, Sabin's Polio, MMR (Small Yellow Chickens vaccinated by Sabian's MMR)
Killed VaccinesRabies, Influenza, Salk Polio, HAV (RIP Always)
Recombinant vaccinesHBV (HBsAg)
HPV (types 6, 11, 16, 18)
Naked ____ viruses are infectious on their own (2)+ssRNA (basically mRNA) and dsDNA (except poxviruses and HBV)
Naked ____ viruses are NOT infectious on their own (2)(-)ssRNA and dsRNA
Mneumonic for all DNA virusesHHAPPPPy viruses (Hepadna (HBV), Herpes, Adeno, Pox, Parvo, Papilloma, Polyoma)
Naked RNA virusesCPR Calici, Picorna, Reo
Naked DNA virusesPAPP Parvo, Adeno, Papilloma, Polyoma (Must be naked for a PAPP smear)
Hemagglutinin fn.promotes viral entry
Neuraminidase fn.promotes progeny virion release
Negri BodiesIntracytoplasmic eosinophilic inclusions in axons (cerebellum) in Rabies
Cowdry A BodiesIntranuclear eosinophilic inclusion in HSV
the only dsRNA virusReoviridae (the "Reo" Grande is double wide to prevent illegal immigration)
+ stranded RNA virusesI went to a retro toga party where I drank flavorded Corona and at hippy California pickles
retrovirus, togavirus, flavivirus, coronavirus, hepevirus, calicivirus, picornavirus
DNA virus replication locationnucleus (except poxvirus - carries its own DNA-dependent RNA polymerase)
RNA virus replication locationcytoplasm (except influenza and retroviruses)
Only ssDNA virusparvovirus
Only non-linear DNA virusespapilloma, polyoma, hepadna (circular)
Only non-icosahedral DNA viruspox

DNA Viruses

Question Answer
Mneumonic for all DNA virusesHHAPPPPy viruses (Hepadna, Herpes, Adeno, Pox, Parvo, Papilloma, Polyoma)
Sporadic temporal lobe encephalitis
latent in trigeminal ganglia
HSV-2Genital, neonatal
latent in sacral ganglia
HHV-3VZV - checkenpox, shingles, encephalitis, pneumonia
latent in dorsal root or trigeminal ganglia
post herpatic neuralgia
infxous mononucleosis (fever, hepatosplenomegaly, pharyngitis, lymphadenopathy (esp posterior cervical nodes))
abnormal cells on smear are reactive t-cells (not b cells)
Burkitt's/Hodgkin's lymphoma
nasopharyngeal carcinoma
Latent in B cells
Congenital infxn
mononucleosis (negative Monospot test)
Owl's eye inclusions in infected cells
Latent in mononuclear cells
high fevers for several days that can cause seizures - followed by diffuse macular rash
HHV-8Kaposi's Sarcoma (HIV pts) [usually a superficial, erythematous patch]
HepadnavirusHepatitis B Virus (HBV)
has reverse transcriptase but it's not a retrovirus
AdenovirusFebrile pharyngitis - sore throat
Acute hemorrhagic cystitis
Conjunctivits - "pink eye"
ParvovirusThink ssRBC disease
B19 virus: aplastic crises in sickle cell disease
"slapped cheeks" rash in children (erythrovirus)
RBC destruction in fetus → hydrops fetalis & death
RBC aplasia and rheumatoid arthritis-like sxs in adults
Vaccinia - cowpox ("milkmaid's blisters")
Molluscum contagiosum - flesh-colored dome lesions with central dimple - sexually transmitted and very common
PolyomavirusJC Virus - PML (progressive multifocal encephalopathy) (Junky Cerebrum)
BK Virus - kidney disease in transplant pts (Bad Kidney)
Naked DNA VirusesPapilloma, Polyoma, Adeno, Parvo (Must be naked for a PAPP smear)
HSV TestingPCR - test of choice
Tzank Smear (for HSV-1,-2, and VZV) have Cowdry A Bodies intranuclear

RNA Positive-Sense Viruses - Watch this first:

Question Answer
All ssRNA except (1)reoviridae (dsRNA, The "Reo" Grande is twice as wide to prevent illegal immigration)
(+)ssRNA virsuesRetro-, toga-, flavi-, corona-, hepe- (HEV), calici-, picorna (RETRO TOGA party drinking FLAVored CORONA and ate HIPPY CALIfornia PICkles)
All replicate in ___ (except 2)cytoplasm (except influenza and retrovirus)
Which (+) RNA are non-envelopedReo, Pico, Hepe, Calici
Shape of all (+) RNA virusesIcosahedral (except Corona makes you spin - helical)
Picornaviruses(PERCH) Polio, Echo, Rhino, Coxsackie, HAV (all fecal-oral minus rhino) (all cause aseptic meningitis (except rhino and HAV)
Poliovirus - Salk (killed) and Sabin (live) vaccines
Echovirus - aseptic meningitis
Rhinovirus - "common cold" - acid labile so it's killed in the stomach
--- aseptic meningitis
--- herpangina (mouth blisters, fever)
--- hand, foot, and mouth disease
--- myocarditis
HAV - acute viral hepatitis
FlavivirusesHepatitis Cheese Virus
The Dengue cheese is rotten and Yellow (fever)
West Nile mosquitos from St. Louis ate holes in it
All are arbo viruses except for Hep C
Yellow Fever - high fever, black vomit, jaundice - Aedes mosquito - monkey/human reservoir
ParamyxovirusesParainfluenza, RSV, Rubeola (Measles), mumps
ReovirusesRotavirus (rotating soccer ball)
- #1 cause of fatal diarrhea in children during winter
- segmented
- the only dsRNA virus
- Villous destruction with atrophy leads to ↓ absorption of Na and loss of K

Coltivirus (he should've rode a colt up the mountain)
- Colorado tick fever
HepevirusHepatitis E virus
CalicivirusesNorovirus (while in California, he hopped on a cruise shipp that was made in Norway)
viral gastroenteritis
TogavirusesA blonde chick (Rubella) riding a horse (Western/Eastern equine encephalitis) at the Toga party.
Rubella - German (3-day) measles
- fever
- Postauricular adenopathy
- lymphadenopathy
- arthralgial
- fine truncal rash that starts on head and moves down
- Infxn is serious if it's congenital
RetrovirusesWho knows what they did back in the day at those retro parties: HIV, HTLV (T-cell leukemia)
Has reverse transcriptase
Coronavirus"Common cold" and SARS
helical even though it's a (+) RNA virus - Corona makes you spin

RNA Negative-Sense Viruses - Watch this first:

Question Answer
BunyavirusesThe 3-eared bunny is actually a ghost, back from the Crimean-Congo war to Hant the Sandflies of the Californian Rift Valley
3 segments
Arbovirus: Crimean-Congo hemorrhagic fever, California encephalitis, Sandfly/Rift Valley fevers
Hantavirus - hemorrhagic fever, pneumonia
Bullet that kills the Bunny
ArenavirusesThe mice on both sides of the field have lattsa fever for their team. And LCMV
Lassa fever encephalitis - spread by mice
LCMV - lymphocytic choriomeningitis virus
both = 2 segments
FilovirusWorms, the spectators at the arena, are wearing Fila shoes, smoking Marboro cigs, and dying from ebola.
Ebola/Marburg hemorrhagic fever - often fatal.
OrthomixovirusesA spider, with 8 legs, bites you and you get influenza.
- contains hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release)
- Pts at risk for fatal bacterial superinfection
- Rapid genetic changes
- Killed vaccine given each fall (IM)
- Live vaccine: replicates in the nose, not the lungs - given to children intranasally
ParamyxovirusesWhat do you do after the influenza spider bit you? Call the Paramedics - duh.
First you hear the siren: Mumpssssss, measles measles measles.
Then you get RSV - I mean CPR (bronchiolitis in babies)
Finally, you remember what's going on: picked up by the paramedics for influenza - parainfluenza (seal-like barking cough).
All of these cause infxns in children.
Respiratory trac infection (bronchiolitis, pneumonia)
Contain surface F (fusion) protein - causes respiratory epithelial cells to fuse and form multinucleated cells.
Palivizumab (MAB to F protein) prevents pneumonia cause by RSV in premature infants.
Delta virusHDV - "defective" virus that requires HBV co-infection.
Shape of negative-sense RNA viruses Helical capsid symetry
RNA structure of negative-sense RNA virusesLinear, except for ABD are circular (Arenaviruses, Bunyaviruses, Delta virus)
What does negative-sense actually mean?Must transcribe negative strand to positive.
Virion brings its own RNA-dependent RNA polymerase.
MeaslesKoplik spots (red spots with blue/white center on buccal mucosa)
descending maculopapular rash
Subacute sclerosing panencephalitis - later years
Rare encephalitis and giant cell pneumonia (immunosuppressed)
Rash presents last and includes hands/feet (vs. truncal rubella rash)
DON'T confuse with roseola (high fevers - seizures)
Mumps virusCheeks and balls like POM-poms
Meningitis (aspetic)
(Can cause sterility if caught after puberty)
Rabies virusNegri bodies - found in Purkinje cells of cerebellum
Incubation period of weeks to months (retrograde travel up nerves)
Get the wound - clean it and vaccinate with/without rabies immune globulin
Disease: fever, malaise → agitation, photophobia, hydrophobia → paralysis, coma &rarr: death

Hepatitis Viruses

Question Answer
A & Efecal-oral (E 0 waterborne epidemics)
No carrier
Short incubation
No HCC risk
A - Asymptomatic, Acute, Alone
E - Enteric, Expectant mothers (high mortality), Epidemic
B/C/DCarrier - yes
Long incubation (except HDV super-infxn)
HCC risk - yes
HBVthe only DNA hepatitis virus (hepadnavirus)
Parenteral, sexual, & maternal-fetal transmission
the virus uses its own DNA-dependent DNA polymerase to make full double-stranded DNA → the host RNA polymerase transcribes mRNA from the viral DNA → makes the viral proteins (lazy virus)
HCVRNA flavivirus
Transmission: blood, IV drug use, post-transfusion
HCC risk (yes) from chronic inflammation
C: Chronic, Cirrhosis, Carcinoma, Carrier
HDVRNA delta virus
Transmission: Parenteral, sexual, maternal-fetal
Usually needs co-infxn with HBV (long incubation)
Superinfection - short incubation
D: Defective Virus

HAV Serology

Question Answer
Anti HAVAb (IgM)best to detect active HAV
Anti-HAVAb (IgG)indicates (1) prior HAV infection or (2) prior HAV vaccination, protects against reinfection

HBV Serology

Question Answer
HBsAgHBV surface antigen, indicates hepatitis B infection
Anti-HBsAgAb to HBsAg (surface antigen), indicates immunity to HBV
HBcAgHBV core antigen
Anti-HBcAgAb to HBcAg (core antigen), positive during window period
Anti-HBcAG (IgM)acute/recent HBV infection
Anti-HBcAG (IgG)chronic HBV disease
HBeAgHBV core antigen, indicates active replication, extremely high transmissibility
Anti-HBeAgAb to HBeAg (core replication antigen), indicates low transmissibility
Window Period Serologyonly see Anti-HBcAb
HBeAgextremely high transmissibility
Immunized Serologyonly see Anti-HBsAg
Acute HBV Serology(1) HBsAg (2) HBeAg (3) Anti-HBcAb IgM
Immune due to HBV Vaccine1) HBsAg-negative 2)Anti-HBcAg-negative 3) Anti-HBsAg-positive
Immune due to previous HBV Infection1) HBsAg-negative 2)Anti-HBcAg-positive 3) Anti-HBsAg-positive



Question Answer
3 structural genesenv (envelope gp41,gp120), gag (capsid), pol (RT polymerase)
env(1) gp120 (attachment to host T Cell) (2) gp41 (fusion and entry)
gagp24 (capsid protein) (24 yos hate gagging)
polreverse transcriptase
gp120docking protein (can cross placenta)
gp41transmemebrane glycoprotein
p24caspid (gag)
p17matrix (shell) (i was 17 when i saw the matrix)
HIV binds what 2 coreceptorsCXCR4 or CCR5
HIV binds what target cellCD4+ T cells
Mutation resulting in slower courseheterzygous CCR5 mutation
Mutation resulting in immunityhomozygous CCR5 mutation


Question Answer
AIDS diagnosis (3)(1) ≤200 CD4+ (2) HIV (+) with AIDS indicator condition (3) CD4/CD8 ratio <1.5
Screening TestELISA (high sensitivity)
Confirmation TestWestern Blot (high specificity)
Ring enhancing lesions in brainToxoplasma gondii
HIV pneumoniaPneumocystis jiroveci (formerly carinii (PCP))

HIV-positive - Diseases

Clinical presentationFindings/labsPathogen
Low-grade fevers
tongue ulcer
Oval yeast cells in macrophages
Histoplasma capsulatum
Fluffy white cottage-cheese lesionsPseudohyphae
oral if CD4<400
Esophageal if CD4<100
C. albicans
Superficial vascular proliferationBiopsy - neutrophilic inflammationBartonella henselae (bacillary angiomatosis)
Chronic, watery diarrheaAcid-fast cysts seen in stool especially when CD4<200Cryptosporidium spp.
EncephalopathyReactivation of latent virus → demyelination
JC virus reactivation (cause of PML)
AbscessesMany ring-enhancing lesions on imaging
Toxoplasma gondii
MeningitisIndia ink, yeast with narrow-based budding and large capsule
Cryptococcus neoformans
RetinitisCotton-wool spots on funduscopic exam
Possible esophagitis
Dementiamust differentiate from other causesdirectly caused by HIV
Superficial neoplastic proliferatoin of vasculatureBiopsy, lymphocytic inflammationHHV-8 (Kaposi's sarcoma)
Hairy leukoplakialateral tongueEBV
Non-Hodgkin's lymphoma (large cell type)Oropharynx (Waldeyer's ring)EBV
Squamous cell carcinmoaanus (MwhswM)
cervix (females)
Primary CNS lymphomaFocal or multiple
differentiate from toxoplasmosis
Interstitial pneumoniaIntranuclear (owl's eye) inclusion bodiesCMV
Invasive aspergillosisPleuitic pain
Infiltrates on imaging
Apergillus fumigatus
PneumoniaEsp. with CD4<200Pneumocystis jirovecii
TB-like diseaseEsp w CD4<50Mycobacterium avium-intracellulare