Positive Stranded RNA Viruses

Question 1

Endemic area of SARS-CoV

Answer 1

Far East, Toronto, China

Question 2

Function of gp120 and gp41 structural proteins of HIV?

Answer 2

gp120 (surface) ▶️ binds CD4, coreceptors CCR5 (macrophages), CXCR4 (T cells)
gp41 (transmembrane) ▶️ viral fusion to host cell

Question 3

Role of Nef in HIV infection

Answer 3

⬇️ CD4 and MHC I expression

*required to AIDS progression

Question 4

What is the difference between RT-PCR and PCR for HIV laboratory analysis?

Answer 4

• RT-PCR ▶️ circulating viral RNA (viral load) ▶️ monitor efficacy of treatment, best prognostic indicator during infection
• PCR ▶️ integrated provirus

Question 5

Enterovirus that can cause myocarditis

Answer 5

Coxsackie B

Question 6

What disease can all enteroviruses cause?

Answer 6

Aseptic meningitis

Question 7

First and second most common cause of common cold

Answer 7

1. Rhinovirus

2. Coronavirus

Question 8

Most common cause of gastroenteritis in USA

Answer 8

Norwalk virus - 60% of gastroenteritis

Question 9

What do St. Louis encephalitis virus and west Nile encephalitis virus have in common?

Answer 9

Arbovirus type ▶️ arthropod-borne
Vector: mosquito (culex), host: birds
Dx: serology, hemagglutination inhibition, ELISA, latex particle agglutination
Prevent: vector control

Question 10

Genetic drift has been best described in which agent?

Answer 10

HIV ▶️ makes difficult to fight with it, complicates to make an effective vaccine