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Priming immunization with DNA augments immunogenicity of recombinant adenoviral vectors for both HIV-1 specific antibody and T-cell responses.

ABSTRACT: Induction of HIV-1-specific T-cell responses relevant to diverse subtypes is a major goal of HIV vaccine development. Prime-boost regimens using heterologous gene-based vaccine vectors have induced potent, polyfunctional T cell responses in preclinical studies.The first opportunity to evaluate the immunogenicity of DNA priming followed by recombinant adenovirus serotype 5 (rAd5) boosting was as open-label rollover trials in subjects who had been enrolled in prior studies of HIV-1 specific DNA vaccines. All subjects underwent apheresis before and after rAd5 boosting to characterize in depth the T cell and antibody response induced by the heterologous DNA/rAd5 prime-boost combination.rAd5 boosting was well-tolerated with no serious adverse events. Compared to DNA or rAd5 vaccine alone, sequential DNA/rAd5 administration induced 7-fold higher magnitude Env-biased HIV-1-specific CD8(+) T-cell responses and 100-fold greater antibody titers measured by ELISA. There was no significant neutralizing antibody activity against primary isolates. Vaccine-elicited CD4(+) and CD8(+) T-cells expressed multiple functions and were predominantly long-term (CD127(+)) central or effector memory T cells and that persisted in blood for >6 months. Epitopes mapped in Gag and Env demonstrated partial cross-clade recognition.Heterologous prime-boost using vector-based gene delivery of vaccine antigens is a potent immunization strategy for inducing both antibody and T-cell responses.ClinicalTrials.gov NCT00102089, NCT00108654.

SUBMITTER: Koup RA

PROVIDER: S-EPMC2814848 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Priming immunization with DNA augments immunogenicity of recombinant adenoviral vectors for both HIV-1 specific antibody and T-cell responses.

Koup Richard A RA Roederer Mario M Lamoreaux Laurie L Fischer Jennifer J Novik Laura L Nason Martha C MC Larkin Brenda D BD Enama Mary E ME Ledgerwood Julie E JE Bailer Robert T RT Mascola John R JR Nabel Gary J GJ Graham Barney S BS

PloS one 20100202 2

<h4>Background</h4>Induction of HIV-1-specific T-cell responses relevant to diverse subtypes is a major goal of HIV vaccine development. Prime-boost regimens using heterologous gene-based vaccine vectors have induced potent, polyfunctional T cell responses in preclinical studies.<h4>Methods</h4>The first opportunity to evaluate the immunogenicity of DNA priming followed by recombinant adenovirus serotype 5 (rAd5) boosting was as open-label rollover trials in subjects who had been enrolled in pri ...[more]

PMID: 20126394

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Project description:There are conflicting reports concerning the impact of prior vector priming on the immunogenicity of recombinant-Salmonella-based vaccines. A comparison of experimental protocols identified two variables which might account for this inconsistency: the potential of the vector strain to colonize the murine gut-associated lymphoid tissue (GALT) and the nature of the foreign antigen subsequently delivered by the recombinant Salmonella construct. The former was investigated by constructing an aroA mutant of the Salmonella enterica serovar Stanley vector previously used in our laboratory. Although the introduction of an aroA mutation had surprisingly little effect on GALT colonization, it did reduce the strength of antilipopolysaccharide (anti-LPS) antibody responses and the impact of vector priming. Studies were also performed to ascertain the extent to which any observed hyporesponsiveness consequent upon vector priming might be determined by the characteristics of the foreign antigen. S. enterica serovar Stanley was used to deliver either of two Escherichia coli antigens, K88 pilus protein or the LT-B toxin subunit, to vector-primed mice. Both serum immunoglobulin G (IgG) and intestinal IgA responses to K88 were completely abolished, and those to LT-B were significantly reduced, as a consequence of vector priming. When similar experiments were performed with an aroA S. enterica serovar Dublin vector, responses to K88 were significantly reduced but those to LT-B were unaffected by vector priming. Paradoxically, a priming infection with this vector induced stronger anti-LPS antibody responses but was less likely to elicit a state of hyporesponsiveness to subsequently presented foreign antigen. The impact of vector priming thus depends on both the Salmonella strain used and the nature of the foreign antigen, but our present data strengthen concerns that preexisting antivector immunity represents a serious threat to the Salmonella-based vaccine strategy.

Project description:BackgroundTrypanosoma cruzi is the causative agent of Chagas disease. Chagas disease is an endemic infection that affects over 8 million people throughout Latin America and now has become a global challenge. The current pharmacological treatment of patients is unsuccessful in most cases, highly toxic, and no vaccines are available. The results of inadequate treatment could lead to heart failure resulting in death. Therefore, a vaccine that elicits neutralizing antibodies mediated by cell-mediated immune responses and protection against Chagas disease is necessary.Methodology/principal findingsThe "antigen capsid-incorporation" strategy is based upon the display of the T. cruzi epitope as an integral component of the adenovirus' capsid rather than an encoded transgene. This strategy is predicted to induce a robust humoral immune response to the presented antigen, similar to the response provoked by native Ad capsid proteins. The antigen chosen was T. cruzi gp83, a ligand that is used by T. cruzi to attach to host cells to initiate infection. The gp83 epitope, recognized by the neutralizing MAb 4A4, along with His6 were incorporated into the Ad serotype 5 (Ad5) vector to generate the vector Ad5-HVR1-gp83-18 (Ad5-gp83). This vector was evaluated by molecular and immunological analyses. Vectors were injected to elicit immune responses against gp83 in mouse models. Our findings indicate that mice immunized with the vector Ad5-gp83 and challenged with a lethal dose of T. cruzi trypomastigotes confer strong immunoprotection with significant reduction in parasitemia levels, increased survival rate and induction of neutralizing antibodies.Conclusions/significanceThis data demonstrates that immunization with adenovirus containing capsid-incorporated T. cruzi antigen elicits a significant anti-gp83-specific response in two different mouse models, and protection against T. cruzi infection by eliciting neutralizing antibodies mediated by cell-mediated immune responses, as evidenced by the production of several Ig isotypes. Taken together, these novel results show that the recombinant Ad5 presenting T. cruzi gp83 antigen is a useful candidate for the development of a vaccine against Chagas disease.

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Priming immunization with DNA augments immunogenicity of recombinant adenoviral vectors for both HIV-1 specific antibody and T-cell responses.

Publications

Priming immunization with DNA augments immunogenicity of recombinant adenoviral vectors for both HIV-1 specific antibody and T-cell responses.

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