[HIV infection and long-term non progressor]

AIDS(acquired immunodeficiency syndrome) is caused by HIV(human immunodeficiency virus) that belongs to the lentivirus group. Generally, the length of time between HIV infection and development of AIDS is considered to be 10 years on average, but a few percent of infected persons-so-called long-term non progressor, do not develop AIDS even more than 10 years after infection. In long-term non progressors, it has been described that 1) there is a low viral load, 2) isolated HIV is relatively non virulent type, 3) antibody to HIV do not enhance virus propagation, 4) type 1 cytokines is more dominant than type 2, and 5) antiviral activity of CD8+ cell is strong. Thus, in long-term non progressors, the immune-response actively suppress HIV proliferation, so that viruses are controlled at low level.