Assessment of HIV vaccine development: past, present, and future

How should HIV vaccine efficacy trials be conducted? Diverse U.S. communities speak out

Developing an effective vaccine remains a critical long-term approach to HIV prevention. Every efficacy trial should be responsive to the concerns of participating communities because the successful development of an HIV preventive vaccine will require long-term involvement of people who have been marginalized and who distrust the government and biomedical research. Using qualitative interviews and purposive sampling, we elicited recommendations regarding how vaccine efficacy trials should be conducted from 90 members of communities that have been disproportionately affected by HIV/AIDS: injection drug users, gay men, and African Americans. The most common recommendation was for complete disclosure of all aspects of the trial. Other themes included participant and community education, who to include in trials, preventing harm, trust, community involvement, researcher attributes, and respect for participants. Developing positive, respectful and collaborative experiences with community members will facilitate vaccine research because negative experiences and unfavorable community reactions can greatly impede success in future trials.

Development of dengue virus replicons expressing HIV-1 gp120 and other heterologous genes: a potential future tool for dual vaccination against dengue virus and HIV

BACKGROUND

Toward the goals of providing an additional vector to add to the armamentarium available to HIV vaccinologists and of creating a bivalent vaccine effective against dengue virus and HIV, we have attempted to create vectors which express dengue virus non-structural proteins and HIV immunogens. Previously we reported the successful construction of dengue virus replicons which lack structural genes necessary for virion release and spreading infection in culture but which can replicate intracellularly and abundantly produce dengue non-structural proteins. Here we attempted to express heterologous genetic material from these replicons.

RESULTS

We cloned into a Deltapre-M/E dengue virus replicon genes for either green fluorescent protein (GFP), HIV gp160 or HIV gp120 and tested the ability of these constructs to express dengue virus proteins as well as the heterologous proteins in tissue culture after transfection of replicon RNA.

CONCLUSIONS

Heterologous proteins were readily expressed from these constructs. GFP and gp120 demonstrated minimal or no toxicity. Gp160 expressing replicons were found to express proteins abundantly at 36 hours post transfection, but after 50 hrs of transfection, few replicon positive cells could be found despite the presence of cellular debris positive for replicon proteins. This suggested that gp160 expressed from dengue virus replicons is considerably more toxic than either GFP or gp120. The successful expression of heterologous proteins, including HIV gp120 for long periods in culture suggests this vector system may be useful as a vaccine vector, given appropriate delivery methods.

Polyvalent envelope glycoprotein vaccine elicits a broader neutralizing antibody response but is unable to provide sterilizing protection against heterologous Simian/human immunodeficiency virus infection in pigtailed macaques

The great difficulty in eliciting broadly cross-reactive neutralizing antibodies (NAbs) against human immunodeficiency virus type 1 (HIV-1) isolates has been attributed to several intrinsic properties of their viral envelope glycoprotein, including its complex quaternary structure, extensive glycosylation, and marked genetic variability. Most previously evaluated vaccine candidates have utilized envelope glycoprotein from a single virus isolate. Here we compare the breadth of NAb and protective immune response following vaccination of pigtailed macaques with envelope protein(s) derived from either single or multiple viral isolates. Animals were challenged with Simian/human immunodeficiency virus strain DH12 (SHIV(DH12)) following priming with recombinant vaccinia virus(es) expressing gp160(s) and boosting with gp120 protein(s) from (i) LAI, RF, 89.6, AD8, and Bal (Polyvalent); (ii) LAI, RF, 89.6, AD8, Bal, and DH12 (Polyvalent-DH12); (iii) 89.6 (Monovalent-89.6); and (iv) DH12 (Monovalent-DH12). Animals in the two polyvalent vaccine groups developed NAbs against more HIV-1 isolates than those in the two monovalent vaccine groups (P = 0.0054). However, the increased breadth of response was directed almost entirely against the vaccine strains. Resistance to SHIV(DH12) strongly correlated with the level of NAbs directed against the virus on the day of challenge (P = 0.0008). Accordingly, the animals in the Monovalent-DH12 and Polyvalent-DH12 vaccine groups were more resistant to the SHIV(DH12) challenge than the macaques immunized with preparations lacking a DH12 component (viz. Polyvalent and Monovalent-89.6) (P = 0.039). Despite the absence of any detectable NAb, animals in the Polyvalent vaccine group, but not those immunized with Monovalent-89.6, exhibited markedly lower levels of plasma virus than those in the control group, suggesting a superior cell-mediated immune response induced by the polyvalent vaccine.