|gag||All||Group-specific antigen: core and capsid proteins|
|pol||All||Polymerase: reverse transcriptase, protease, integrase|
|tax||HTLV||Transactivation of viral and cellular genes|
|tat||HIV-1||Transactivation of viral and cellular genes|
|rex||HTLV||Regulation of RNA splicing and promotion of export to cytoplasm|
|rev||HIV-1||Regulation of RNA splicing and promotion of export to cytoplasm|
|nef||HIV-1||Alteration of cell activation signals; progression to AIDS (essential)|
|vif||HIV-1||Virus infectivity, promotion of assembly, blocks a cellular antiviral protein|
|vpu||HIV-1||Facilitates virion assembly and release, decrease of cell surface CD4|
|vpr (vpx*)||HIV-1||Transport of complementary DNA to nucleus, arresting of cell growth|
|LTR||All||Promoter, enhancer elements|
From Murray PR, Rosenthal KS, Pfaller MA: Medical Microbiology, 6th ed. Philadelphia, Mosby, 2009, Table 64-2.
26-1 Genome structure of human retroviruses: (A) HTLV-1 and (B) HIV. The basic retrovirus genome consists of the long terminal repeat (ltr) group–specific antigen (capsid proteins)(gag)-enzymes(polymerase, integrase, protease)(env) and the glycoproteins (env). Complex retroviruses, such as HIV have additional proteins that enhance their virulence. These are described in Table 26-1. (Redrawn from Belshe RB: Textbook of Human Virology, 2nd ed. St Louis, Mosby, 1991. In Murray PR, Rosenthal KS, Pfaller MA: Medical Microbiology, 6th ed. Philadelphia, Mosby, 2009, Fig. 64-4.)
• Reverse transcriptase carried in the virion synthesizes a complementary DNA (cDNA) from viral genome, forming an RNA-DNA hybrid. The same enzyme then degrades the RNA strand and synthesizes a complementary DNA strand, forming double-stranded viral DNA.