Question

What enzymes involved in genome replication of retroviruses would make good antiviral targets? Why?

Answer 1

viruses are ultimate expression of parasitism: they not only take nutrition from the host cell but also direct its metabolic machinery to synthesize new virus particles. viral chemotherapy, therefore,is difficult,as it would require interference with cellular meatbolism in the host. virus directed enzymes have been identified in the infected cell and some viruses have few enzymes of their own which may have higher affinities for some antimetabolities or inhibitors than thye regular cellular enzymes.In viral infection like HIV, on the template of single starnded RNA genome of HIV a double stranded DNA copy is produced by the viral reverse transcriptase. This DNA transclocates to the nucleus and is integrated with chromosomal DNA of the host cell, which then starts transcribing viral genomic RNA, viral regulatory and structural proteins are produced and finally the viral particles are assembled.

antiviral drug selectively inhibits  the viral reverse transcriptase (RNA dependent DNA polymerase) . some drugs like acyclovir inhibits DNA polymerase.

certain drugs inhibits replication of virus.these drugs acts on the early step that is uncoating and sometimes acts on the late step ie viral assembly in viral replication.

interferons are low molecular weight glycoprotein cytokines produced by host cells in response to viral infections. interferons bind to specific cell surface receptors and affect viral replication at multiple steps: viral penetration, synthesis of viral mRNA, assembly of viral particles. they inhibit translation.