Question

Which of the following viruses depend on virion enzymes to start the virus replication cycle after delivery of the genome to the host cell? a poliovirus b) influenza c) retrovirus d) all of the above e) b and c of the above ONE or MORE of the following statements is correct. Using the key below, choose the appropriate answer: a) if only 1, 2, and 3, are correct b) if only 1 and 3 are correct c) if only 2 and 4 are correct d) if only 4 is correct e) if all are correct Regarding poliovirus l. it uses Cap-dependent translation to synthesize a polyprotein 2. genome and antigenome synthesis use a protein priming mechanism 3. its mRNA is processed by RNA splicing before it is translated 4. it inhibits host cell vesicle transport causing their cytoplasmic accumulation

Answer 1

Problem 3. Influenza virus requires the virion protein RNA-dependent RNA polymerase & Retrovirus uses virion enzyme reverse transcriptase to produce DNA from its RNA. While Polio virus has positive-stranded RNA so it can be directly translated by host cells.

So the answer is (e)

Problem 4.

1. IRES allows the polio virus to recruit cellular translation machinery via cap-independent mechanisms. So the statement is false

2. The small protein VPg is the primer for both (+) and (−) RNA strand synthesis. So the statement is true

3. Its mRNA is directly processed and no splicing occurs. So the statement is false

4. Polio virus inhibits the host cell transport vesicles by supressing its fusion with the the Golgi body. So the statement is true

So the correct option is C (as only 2 & 4 are correct)