Humoral immune responses in human HIV-1 infection clearance of initial burst of virus replication and protection against disease progression.

An attempt is made to summarize the evidence that humoral immune responses in natural HIV-1 infection play a role in clearance of the initial burst of replication as well as in protection against rapid disease progression. Therefore, the so-called "asymptomatic carrier state" was defined on the basis of immunological characteristics, such as CD4+ cell number, CD45RA-CD29+ cell number, CD4+ proliferative responses to anti-CD3 mAbs and soluble activation markers, as well as virological characteristics such as the state of the viral genome in the cell, levels of genomic RNA production, antigenemia, viremia and virus phenotype. During natural infection two major classes HIV-1 neutralizing and cell-fusion inhibiting antibodies are elicited. One population directed against mostly continuous epitopes localized in the third variable domain (V3) of the envelope and one against discontinuous epitopes of the envelope. The last population blocks gp120-CD4 attachment, the first does not. The role of each of these populations of functional antibodies, in the clearance of viremia and the maintenance of the asymptomatic carrier state is discussed.