Immunologic and Pathogenic Aspects of HIV Infections: Current Hypothesis

Abstract

The acquired immunodeficiency syndrome (AIDS) (Gottlieb et al., 1981) is the major clinical expression of infection with the Human Immunodeficiency Virus (HIV) (Barre-Sinoussi et al., 1983) in man, and with the Simian Immunodeficiency Virus (SIV) in Macaques (Daniel et al., 1985). These viruses (HIV 1 and 2, and SIV _MAC) belong to the lentivirus family, which are retroviruses. Although theses viruses are highly cytopathogenic for numerous CD4+ cells in vitro (Klatzmann et al., 1984; Haseltine, 1988; Gallo, 1988), they induce in vivo a clinical picture for the main characteristics are a long dormant stage, and a slow decrease of CD4+ cells in blood and haematopoïetic systems. These differences between in vitro and in vivo behaviours might be related to several features, including, first, close relationships between latent infection and expression of both intracellular activation signals and cytokines, and, second, infection of monocyte/macrophages, in which lentivirus replication is essentially intracellular. Therefore, HIV and SIV in vivo pathogenicities may be related to the viral genetic mechanisms, to the nature of the target cells, to the activation level of the infected cells, and to the probability of these cells being activated by cytokines and/or intracellular signals.