Anti-F(ab')2 antibody in HIV type 1 infection: relationship to hypergammaglobulinemia and to antibody specific to the V3 loop region of glycoprotein 120

Predictors of HIV-specific lymphocyte proliferative immune responses induced by therapeutic vaccination

We treated a cohort of 38 HIV-infected individuals with a therapeutic vaccine (REMUNE, HIV-1 Immunogen) in an open label study. We then determined whether baseline parameters, such as CD4 cell count, viral load and IgG levels, were predictive of the magnitude of the HIV-specific lymphocyte proliferative responses (LPRs). We demonstrate herein that there is a significant enhancement from baseline for both HIV and p24 antigen-stimulated LPRs after immunization. Using a responder definition of a stimulation index of >5 on at least two post-immunization time-points, 29/38 (76%) responded to HIV-1 antigen while 27/38 (71%) responded to native p24 antigen. Viral load and total IgG were negatively correlated, while CD4 cell counts were positively associated with the magnitude of the HIV antigen LPR. In a multivariable analysis, baseline CD4 was the best predictor of HIV antigen LPR post-immunization.

V3 variation in HIV-seropositive patients receiving a V3- targeted vaccine

OBJECTIVE

To analyze V3 loop sequences of HIV-1 in three seropositive individuals who exhibited declines in viremia while receiving a V3-targeted vaccine.

DESIGN

Retrospective analysis of case series at an HIV Clinic, University of Tel Aviv.

PATIENTS

Three HIV-1-seropositive, PPD-DTHR-positive (PPD, Siebert purified protein derivative of tuberculin; DTHR, delayed type hypersensitivity reaction) individuals who had been inoculated with a mixture of PPD-cross-linked V3 peptides from five HIV strains and then exhibited declines in HIV-1 viremia during the course of vaccination in the absence of combination antiretroviral therapy and whose virus levels resurged once vaccine boosting was discontinued.

RESULTS

Declines in viremia were observed even when the viral V3 sequences of the patients' HIV differed by at least one or two amino acid residues from those of the five peptides in the vaccine. Although viral mutants with amino acid substitutions within V3 appeared during vaccination, plasma virus loads remained at low levels for several months after these variants appeared. About a year after boosting was discontinued, anti-V3 peptide antibodies in the patients had declined and plasma virus returned to the prevaccination levels or higher. Compared with the isolates that predominated during the course of vaccination, the resurgent viruses contained zero to six amino acid residue differences in the V3 loop but few synonymous substitutions.

CONCLUSIONS

Viruses with altered V3 sequences did emerge but did not result in increased viremia during the course of vaccination. In two individuals where V3 mutations were absent in the virus that re-emerged after vaccine boosting ceased, resurgence could not have been a consequence of V3 changes.