Which property of HIV renders the virus difficult to eradicate by the body's immune defenses and also limits the efficacy of drug therapies?

Question

What will be an ideal response?

Answer 1

HIV is a retrovirus that uses the enzyme reverse transcriptase to complete its life cycle. This enzyme uses the single-stranded RNA genome of HIV as a template to make a double-stranded DNA (complementary DNA or cDNA) that integrates into the host genome as a provirus. Reverse transcriptase is an error-prone DNA polymerase that lacks proofreading capabilities. Mutations are therefore introduced into the HIV genome each time it is replicated. Such rapid mutation leads to variant viruses with modified antigens, which thus escape detection by antibodies or cytotoxic T cells specific for the original epitopes.
The high rate of mutation in HIV also causes the emergence of resistance to the antiviral drugs used to treat HIV infection, which are mainly drugs that inhibit viral reverse transcriptase and protease. Mutation produces viruses with mutant enzymes that are not blocked by the drugs. Multidrug regimes are used to try to eliminate the virus before the multiple mutations needed to resist all of the drugs have accumulated.