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Separate, coadministration of investigational HIV, HCV vaccines induce similar responses
BARCELONA, Spain — Phase 1 data presented at the International Liver Congress showed that investigational HIV and hepatitis C virus vaccines administered simultaneously in a prime-boost regimen were well-tolerated and induced similar immune responses compared with individual vaccine administration.
“Finding effective vaccinations against the world’s biggest killers is a huge and pressing problem,” Laurent Castera, MD, PhD, European Association for the Study of the Liver secretary-general, said in a press release. “This study shows for the first time that it is possible to generate simultaneous immune response against diseases HCV and HIV, raising the possibility of a combined vaccination.”
Felicity Hartnell, MB, of the University of Oxford, and colleagues compared the safety and efficacy of the HCV and HIV vaccines in 32 healthy volunteers. All participants were primed at baseline and received a booster dose enclosed in an MVA vector at 8 weeks. Eight participants received the HCV vaccine AdCh3NSmut1 and booster dose MVA.NSmut; eight participants received the HIV vaccine ChAdV63.HIVconsv and booster dose MVA.HIVconsv; and 16 participants concurrently received the HCV and HIV vaccines and booster doses.
No serious adverse events occurred during the study, according to the researchers. They reported that the booster dose was more reactogenic, accounting for 45% of grade 1 events, 70% of grade 2 events and 72% of grade 3 events.
Results showed that vaccine priming induced immune responses with AdCh3NSmut1 (mean peak = 608.5 spot forming units per million peripheral blood mononuclear cells) and ChAdV63.HIVconsv (mean peak = 785 SFU/10⁶ PBMC) alone. The responses increased after booster doses MVA.NSmut (mean peak = 4,260 SFU/10⁶ PBMC) and MVA.HIVconsv (mean peak = 3,760 SFU/10⁶ PBMC).
Coadministration did not have an impact on the breadth or magnitude of immune responses compared with individual vaccine administration, the researchers wrote. During coadministration, peak responses to the HCV prime and boost vaccines were 1,184 SFU/10⁶ PBMC and 5,297 SFU/10⁶ PBMC, and peak responses to the HIV vaccines were 780 SFU/10⁶ PBMC and 3,081 SFU/10⁶ PBMC, respectively.
In a separate analysis, Hartnell and colleagues readministered the HCV vaccine AdCh3NSmut1 and booster dose MVA.NSmut to participants to investigate whether the vaccines can further enhance immune responses at varying intervals. After initial HCV vaccinations at baseline and week 8, five volunteers received AdCh3NSmut1 at 16 weeks and MVA.NSmut at 24 weeks; four volunteers received AdCh3NSmut1 at 61.5 weeks (range 39-84) and MVA.NSmut at 69.5 weeks (range 47-92); and five volunteers received only MVA.NSmut at 40 weeks.
Revaccination with both vaccines after the shorter interval had no effect (P = .004); however, the researchers found that revaccination after the longer interval induced immune responses similar to those observed after initial vaccination of AdCh3NSmut1 (mean peak = 789 SFU/10⁶ PBMC) and MVA.NSmut (1,857 SFU/10⁶ PBMC). The single MVA.NSmut vaccination at week 40 also was effective (mean peak = 1,078 SFU/10⁶ PBMC), Hartnell and colleagues wrote.
The researchers concluded that revaccination at a delayed interval enhanced immune responses against HCV and may result in long-term immunity. – by Stephanie Viguers
References:
Hartnell F, et al. Abstract PS025. Presented at: International Liver Congress; April 13-17, 2016; Barcelona, Spain.
Hartnell F, et al. Poster LB-507. Presented at: International Liver Congress; April 13-17, 2016; Barcelona, Spain.
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