Chapter 3 - Biological Properties of HIV-1 and Their Relevance for Aids Pathogenesis

Abstract

The Human Immunodeficiency Virus type 1 (HIV-1) has an error-prone reverse transcriptase enzyme, which combined with the absence of proofreading leads to a misincorporation rate of 10 -4 to 10 -5 per base or approximately one misincorporation pergenome per replication cycle. This biological variability is—with immunological, host-genetic, and cofactors—an important contributor to the great variability in the clinical course of infection as observed among individuals. In different phases of HIV-1 infection, different biological properties of HIV-1 variants seem to play a role in AIDS pathogenesis. During transmission, macrophage tropism seems beneficial for the virus. In the early asymptomatic phase, macrophage tropism not only provides the virus with a mechanism to escape immune surveillance but may also be the basis for undermining the immune system since HIV-l-infected macrophages may cause inappropriate antigen presentation and cytokine dysregulation resulting in T-cell dysfunction. The decline of CD4+ T cells seems to be the ultimate event leading to AIDS.