11.1.1 HIV Life Cycle

HIV is a member of lentivirus family of retroviruses.  RNA viruses that integrate into host chromosome through a double-stranded DNA intermediate provirus. Therefore AIDS is essentially an acquired genetic disease capable of suppressing the immune function (Poeschla, 1996)

All retroviruses contain gog, pol, and env genes. HIV contains numerous other genes including tat, rev, nef, vpu, vif, and vpr which are translated from differentially messenger RNA (mRNA) transcripts. Some of the regulatory functions for these genes are defined, while others are still obscure. (Figure 16)

Figure 16 : HIV genome

Full understanding of the biologic function of these genes and HIV – host interactions facilitate the design for gene therapy treatments for the AIDS. The complexity of HIV-host interactions depends on the functional integration of HIV into the fundamental cells of the immune system. The cellular receptors used for HIV binding and entry are essential receptors for immune function.  HIV utilizes replication and gene expression. For example transcriptional factors that regulate activation of T cells can bind to the viral promoter regions within HIV LTR and regulate virus gene expression. Also, regulatory gene products from HIV, such as tat, can bind to host gene – promoter regions and induce expression of regulatory factors that are important for the immune system. HIV integrates into the host genomes and also functionally integrates into the complex regulatory machinery of the immune system cells (Brother, 1996).