Engineering RENTA, a DNA prime-MVA boost HIV vaccine tailored for Eastern and Central Africa

Abstract

For the development of human immunodeficiency virus type 1 (HIV-1) vaccines, traditional approaches inducing virus-neutralizing antibodies have so far failed. Thus the effort is now focused on elicitation of cellular immunity. We are currently testing in clinical trials in the United Kingdom and East Africa a T-cell vaccine consisting of HIV-1 clade A Gag-derived immunogen HIVA delivered in a prime-boost regimen by a DNA plasmid and modified vaccinia virus Ankara (MVA). Here, we describe engineering and preclinical development of a second immunogen RENTA, which will be used in combination with the present vaccine in a four-component DNA/HIVA-RENTA prime-MVA/HIVA-RENTA boost formulation. RENTA is a fusion protein derived from consensus HIV clade A sequences of Tat, reverse transcriptase, Nef and gp41. We inactivated the natural biological activities of the HIV components and confirmed immunogenicities of the pTHr.RENTA and MVA.RENTA vaccines in mice. Furthermore, we demonstrated in mice and rhesus monkeys broadening of HIVAelicited T-cell responses by a parallel induction of HIVA-and RENTA-specific responses recognizing multiple HIV epitopes.

In Vivo Antigen Stability Affects DNA Vaccine Immunogenicity

“…Thus, T cell induction in both the priming as well as the boosting phase in DNA-modified vaccinia Ankara and DNA-Ad5 prime boost regimens that are currently in clinical trials (38,39) may well benefit from vaccine designs that take Ag stability into account. In this respect, it is noteworthy that the type of fusion gene vaccines used in current and planned large-scale vaccination trials is expected or has in fact been shown to yield instable protein products (40), and may therefore well form suboptimal immunogens.…”

DNA Vaccines: Progress and Challenges

“…Where larger polypeptides were coexpressed with short peptides, responses to the longer protein tended to dominate, suggesting that presentation of longer or more native polypeptides may be more efficient. Recent designs favor the use of larger sequence elements, with blocks of sequence rearranged or mutated to eliminate biological activities (30,36). These Ag designs will be reaching clinical trials in the near future.…”

Induction of long‐lasting multi‐specific CD8+ T cells by a four‐component DNA‐MVA/HIVA‐RENTA candidate HIV‐1 vaccine in rhesus macaques

“…These doses and timing mimicked those of the HIVA vaccines used in clinical trial IAVI 006 (manuscript in preparation). To facilitate detailed analyses of vaccineinduced CD8 + T cell responses in pre-clinical NHP studies, two immunodominant SIV-derived Mamu-A*01-restricted epitopes, CTPYDINQM (Gag) and STPESANL (Tat), were incorporated into the HIVA and RENTA immunogens, respectively [25,28]. Employing the corresponding peptides and overlapping peptide pools across the two immunogens, vaccine-elicited T cell responses recognizing multiple epitopes were readily detected after priming with the DNA vaccines ( Fig.…”

“…The preparation of the pTHr.HIVA, pTHr.RENTA, MVA.HIVA and MVA.RENTA vaccines was described previously [25,28]. The plasmid DNA and rMVA were prepared in compliance with Good Manufacturing Practice by Cobra Biomanufacturing (UK) and IDT (Germany), respectively.…”

“…Thus, to broaden responses induced by the HIVA vaccines, we designed a second immunogen RENTA derived from the reverse transcriptase, Env, Nef and Tat proteins of the consensus HIV-1 clade A sequences [28]. We inserted the RENTA gene into plasmid DNA and MVA vectors, and demonstrated induction of RENTA-specific T cell responses in addition to those elicited by HIVA upon HIVA and RENTA vaccine co-delivery [28]. Here, we characterized the DNA-MVA/HIVA-RENTA-elicited immune responses in rhesus macaques in terms of the T cell response longevity, breadth, functionality and ability to recognize CD8 + T cell epitopes from other HIV-1 clades.…”