AEGiS-11IAC: Characterization of the HIV-1 env-specific CD4+ helper T lymphocyte response of DNA-vaccinated rhesus monkeys.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Characterization of the HIV-1 env-specific CD4+ helper T lymphocyte response of DNA-vaccinated rhesus monkeys.

Int Conf AIDS 1996 Jul 7-12; 11:11 (abstract no. We.A.281)
Lekutis C, Shiver JW, Liu MA, Letvin NL; Beth Israel Hospital, Boston, MA, USA. Fax: (617) 667-8210. E-mail: clekutis@bih.harvard.edu.

OBJECTIVES: To determine the breadth of the immune response elicited by HIV-1env DNA vaccination in a nonhuman primate animal model.

METHODS: Two rhesus monkeys were immunized intramuscularly with an HIV-1 gp120 coding plasmid DNA in saline. CD4+ helper T cell lines were generated from peripheral blood mononuclear cells (PBMC) of vaccinated macaques by stimulation with recombinant gp120 followed by expansion in the presence of IL-2 and irradiated autologous PBMC. The peptide epitopes recognized by the T cell lines were mapped in [3H]thymidine incorporation assays using a panel of overlapping 20 amino acid peptides. The cytokine secretion profiles of the T cell lines were determined by ELISA. The cytolytic effector function of the lines was assessed in a chromium release assay.

RESULTS: Long lived CD4+ T cell lines were generated from PBMC of the study monkeys four months after the final DNA boost. Two of the T cell lines have been shown to proliferate in response to a single peptide epitope in a MHC class II DR-restricted fashion, as well as, to autologous B lymphoblastoid cell lines (B-LCL) infected with a recombinant vaccinia virus expressing HIV-1 env (VV-env). The fine specificity of both lines have been mapped to a nine amino acid sequence YKVVKIEPL, located in the carboxy terminus of gp120. All CD4+ T cell lines studied secrete significant amounts of IFN-gamma with no IL-4 production detectable. Interestingly, one line was found to secrete IL-2 in response to PMA and ionomycin and IL-10 in response to antigen. As has been previously observed in humans, several of the rhesus CD4+ T cell lines were found to be weakly cytolytic.

CONCLUSIONS: The cytokine secretion profile of the CD4+ T cell lines generated from the PBMC of the DNA-vaccinated rhesus monkeys corresponds to a Th1 or Th0-like profile. This is consistent with the ability of DNA vaccines to induce vigorous CD8+ CTL responses. Additionally, the CD4+ T cell lines generated from DNA vaccinated rhesus monkeys recognize a peptide epitope presented by VV-env infected B-LCL, suggesting that processing and presentation of this epitope in DNA vaccination occurs in a physiologically relevant manner.

Keywords: AEGIS, T-Lymphocytes, Helper-Inducer, HIV-1, Antigens, CD4, Macaca mulatta, T-Lymphocytes, Antigens, CD8, Epitopes, Vaccines, DNA, Peptides, Animal, Human, ICA11

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WeA281