ABSTRACT
The most important HIV proteins are briefly described in Table 1. Figure 1 shows the HIV-1 genes and corresponding proteins.
III. GENETIC VARIATION Genetic variation is the hallmark of the HIV infection. Diversity leads to the existence of major groups (Group M, or main, and Group O, outlier). The Group M viruses can be divided into at least eight distinct clades (A through H). Clades differ among themselves in 20-30% of their amino acid sequences of the gp120 protein. Isolates within clades (and within the same individuals) vary by 5-20% and are called quasispecies. Diversity can represent a problem for diagnostic tests. This issue is further discussed in the testing section of this chapter.
