Figure 3. Genomic maps of HIV-1 and HIV-2.

Although HIV-1 and 2 have similar genetic structures, the DNA sequences differ by up to 40%. Both viruses have structural and accessory genes that influence replication and pathogenesis (Table 1). Many of these are shared between the two viruses, such as gag and pol; however, only HIV-1 has a gene that encodes Vpu, and Vpx is only encoded by HIV-2. Reproduced from ref. 146.