HIV belongs to the cytopathic retroviruses. RNA is copied into DNA by RT, integrated in the cellular genome as provirus and remains latent until activation. Upon activation, the viral DNA is transcribed into RNA and translated into viral proteins. The viral particles leave the cell by budding. Transmission Macrophages and dendritic cells harbor the virus and protect it from the immune response.
Free virus is found in semen and vaginal fluid, and at lower numbers in urine, saliva, milk, tears.
Transmitted through sexual intercourse, blood transfusion, IV drug use, transplacental transfer. Tat, rev and nef are regulatory proteins. Genetic variation HIV is 65 times more variable than the influenza virus. There are differences between viruses from different individuals and from the same individual when samples are collected at different times. Abs to the conserved region of gp120 block the binding of soluble gp120 to CD4, but not the HIV infectivity.