Question

1. Once a + strand RNA virus has released its genome into a cell, describe the synthesis stage (ONLY) of the virus replicative cycle.

2. Describe the absorption phase of an enveloped RNA virus.

3. How does Acyclovir and its various forms relieve the symptoms of herpes?

4. Contrast mumps infection in children versus an adult male.

5. How do AZT and other nucleotide analogs control the AIDS virus? How do protease inhibitors work?

6. Describe the structure and functions of the hemagglutinin and neuraminidase spikes in influenza virus.

7. Describe the changes over time in virus antigen levels, antibody levels, and CD4 T cells in the blood of an HIV-infected individual.

9. For coccidiodomycoses: state the pathogen genus and species, the source, and pathogenesis and symptoms.

10. Cryptococcus neoformans causes cryptococcosis. It is considered an opportunist. What does this mean and why does this fungus get classified in this manner?

Answer 1

1. After the uncoating of the + strand RNA virus, it replicates in the cytoplasm of the host cell. The nucleic acid ( genetic material; RNA) of the virus itself works as mRNA and facilitate the synthesis of viral proteins.

The viral RNA( serve as mRNA) is translated by host ribosome and a polyprotein is produced. The produced polyprotein goes under the cleaving process at appropriate sites. Now the RNA works as a template for the synthesis of - strand RNA, this process is catalyzed by the RNA polymerase enzyme. The - strand RNA works as a template for the +strand RNA synthesis.

This +strand RNA again works as mRNA and facilitate the synthesis of more viral proteins as translated and more polyproteins formed.

The host cell translated the viral mRNA and facilitate the formation of many enzymes like RNA polymerase(functional proteins) and structural proteins like proteins for capsid or envelope.

RNA polymerase facilitates more viral RNA synthesis.

2. For the entry into the host cell the enveloped RNA virus uses Fusion process. Firstly it attached on the surface of cell with the help of any normal receptor. The binding at the receptor facilitate unfolding of fusion proteins followed by activation of fusion peptides. This change facilitate the viral and host cell membrane fusion followed by the releasing of mycleocapsid into the host cell cytoplasm.

3.Acyclovir inhibits viral DNA polymerase results in termination of nucleotide chain.

4. a. Asymptomatic mumps infection is more common in adults.

b. In symptomatic cases the adults are severely affected than children.

c. Mumps common complication in children is meningitis and in adults it is orchitis

5. HIV is a retrovirus. AZT also known as zidovudine inhibits reverse transcriptase enzyme. It incorporates into growing viral DNA and facilitate chain termination.

Protease enzyme convert polyproteins into functional and structural proteins followed by assembly and releasing of new virion. Protease inhibitors inhibit the protease enzyme activity and further formation of proteins inhibit.