Special

Question 1

Rotavirus

Answer 1

dsRNA
Icosahedral capsid 
No envelope
Segmented (12)
Whiffle ball shape
Fecal oral, resp droplets, nurseries/daycares, highly contagious
5 yrs or less: diarrhea, vomiting, dehydration, fever (infants severe), look for dehydration symptoms 
Survives stomach
Necrotizing enterocolitis
Enzyme immunoassay 
Supportive care 
Live attenuated vaccine

Question 2

HIV properties

Answer 2

2 identical ssRNA segments, positive, diploid
DNA form infectious
Cone shape envelope
Outer protein shell and nucleocapsids
Gag (capsid protein), Pol (polymerase), and Env (envelope glycoproteins)
Env is most variable and forms two precursor proteins
GP120 (SU): attachment
GP41 (TM): fusion protein, allows capsid to release into cytoplasm and initiates infection
High mutation rate

Question 3

HIV enzymes

Answer 3

Reverse transcriptase: RNase activity digests RNA bound to DNA, encoded by pol gene, makes dsDNA intermediates-> provirus
Protease: encoded by gag gene, cleaves polyproteins into mature proteins
Integrase: splices provirus into host cell chromosomal DNA and allows viral expression

Question 4

HIV provirus

Answer 4

6 major proteins
Tat: anti-terminator of transcription, binds Tar, which binds viral mRNA, prevents termination, essential for HIV replication
Rev: regulates expression by promoting mRNA transport from nucleus to cytoplasm
Vif: virion infectivity
Nef: promotes progression to AIDS, downregulates CD4
Vpr and Vpu

Question 5

HIV Transmission

Answer 5

Sexual contact
In utero
Breast milk
Blood for IV drug users

Question 6

HIV Pathogenesis

Answer 6

CCR5 critical in macrophages, CXCR4 in T cells
Seroconversion: mono/ flu-like, 4 weeks, Ab against HIV at end, viral replication increases
latency: chronic infection, 10 years, progressive lymphadenopathy, other disorders appear, CD4 decreases
symptomatic infection: CD4 drops below 450, ARCs, dendritic cells first infected
Chronic established by error rate of RNA

Question 7

HIV Disease

Answer 7

ARC infections: Pneumocystis jirovecii (<200), oral candidiasis (250-500), cryptospordium, TB (250-500), papoviris, herpes, cryptococcus neoformans (<200), taxoplasmosis
MAC complex ~ 50 cells
Kaposi: blue brown rash

Question 8

HIV Diagnosis and Treatment

Answer 8

Lab: CD4 count, OTC screening of P24
Elisa -> positive -> Western blot (definitive test)

HAART: 2 reverse transcriptase inhibitors and 1 protease inhibitor
Combination therapies
Always treat ARCs as well

Pro-exposure prophylaxis: high risk patients, NRTI combo therapy

Question 9

HTLV Properties and Transmission

Answer 9

2 identical ssRNA segments, positive, diploid
Convert RNA into DNA into RNA
Gag, Pol, and Env
Increases IL-2 and it’s receptor expression -> autocrine loop -> proliferation and up regulates proto-oncogenes Fos/PDGF
Mother to infant transmission, sex, IV drug users in US
Africa, Caribbean, Southern Japan, Papa New Guinea, and Siberia

Question 10

HTLV Pathogenesis

Answer 10

Does not have to acquire proto-oncogenes for transformation
V-onc into cell, over expression, overwhelms tumor suppressors, virus integrates into host chromosome
exogenous
Tax: encodes protein, trans-activator, synthesis of IL-2/R -> proliferation and upregulates oncogenes
Rex: regulates splicing, promotes viral progeny
Infects CD4 cells, replicates, latency, disease
Low rate of transformation

Question 11

HTLV Disease and Treatment

Answer 11

Adult T cell Leukemia
Malignancy of T cells
Lymphocytosis, hepatosplenomegaly, CNS involvement -> immunosuppression
High incidence of opportunistic infections
Death in 3-4 months
Chronic Progressive Myelopathy
40-49 yo
Slow and progressive
Neuro deficits, spasticity, demyelination
ELISA -> Western Blot
Manage opportunistic infections