Clonal dominance: cause for a limited and failing immune response to HIV-1 infection and vaccination.

Oligoclonal and monoclonal antibody populations against different HIV-encoded proteins are common in sera from healthy HIV-1-infected individuals. This is especially important when it includes functional antibody repertoires directed at neutralizing cell free virus or inhibiting cell fusion of virus-infected cells. In the host, during the acute viral syndrome following HIV-1 infection, a rapidly replicating, cell-free and genotypically homogeneous viral population is known to arise from the transmitted viral inoculum. Dominant B and possibly T cell clones responsible for both functional and nonfunctional antibodies appear to arise early in response to this initially homogeneous cell-free viral population heralding seroconversion. During the viremic phase, deposition of cell-free virus as either complement coated or as immune complexes (iccosomes) within the germinal centers results in continued and long-term boosting of primed B cells. This saturation of antigen presenting germinal centers and the presence of limited, immunodominant cross-reactive epitopes on the envelope glycoprotein of the closely-related and immune selected viral quasispecies in the host appear to continue the boosting effect of the primed secondary response. This repertoire freeze appears to be responsible for limiting the recruitment of new uncommitted B cells to other functional epitopes or affinity maturation of B-cell clones to escape variants and the subsequent production and quality of functional antibody against the evolving/selected virus populations. This may include in addition to neutralizing and cell fusion inhibiting antibody, direct complement-fixing and/or NK-directed antibody-dependent cell-mediated antibody as well as various effector, helper, or T cell-mediated activity. In addition to antiviral antibody responses, antibody directed to other invading pathogens or opportunistic organisms may also be clonaly restricted. Antibody facilitating infectivity or blocking effective immunity may also be included in this phenomena and thus be over represented by such a mechanism. AIDS vaccines utilizing the envelope must identify these epitopes to avoid creating clonal dominance and therefore possibly limit the breadth and specificity of a humoral response following infection. Furthermore, immunotherapeutic approaches designed to recruit humoral immune effector function must be able to overcome the dominance of noneffective antibodies and restore a normal polyclonal immune response against HIV. Further research, therefore, into the humoral and cellular dysregulating properties of the HIV-1 envelope is warranted.