RT Journal Article
SR Electronic
T1 A simian-adenovirus-vectored rabies vaccine suitable for thermostabilisation and clinical development for low-cost single-dose pre-exposure prophylaxis
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 408013
DO 10.1101/408013
A1 Chuan Wang
A1 Pawan Dulal
A1 Xiangyang Zhou
A1 Zhiquan Xiang
A1 Hooman Goharriz
A1 Ashley Banyard
A1 Nicky Green
A1 Livia Brunner
A1 Roland Ventura
A1 Nicolas Collin
A1 Simon J Draper
A1 Adrian VS Hill
A1 Rebecca Ashfield
A1 Anthony R Fooks
A1 Hildegund C Ertl
A1 Alexander D Douglas
YR 2018
UL http://biorxiv.org/content/early/2018/09/04/408013.abstract
AB Background Estimates of current global rabies mortality range from 26,000 to 59,000 deaths per annum. Although pre-exposure prophylaxis using inactivated rabies virus vaccines (IRVs) is effective, it requires two to three doses and is regarded as being too expensive and impractical for inclusion in routine childhood immunization programmes.Methodology/ Principal Findings Here we report the development of a simian-adenovirus-vectored rabies vaccine intended to enable cost-effective population-wide pre-exposure prophylaxis against rabies. ChAdOx2 RabG uses the chimpanzee adenovirus serotype 68 (AdC68) backbone previously shown to achieve pre-exposure protection against rabies in non-human primates. ChAdOx2 differs from AdC68 in that it contains the human adenovirus serotype 5 (AdHu5) E4 orf6/7 region in place of the AdC68 equivalents, enhancing ease of manufacturing in cell lines which provide AdHu5 E1 proteins in trans.We show that immunogenicity of ChAdOx2 RabG in mice is comparable to that of AdC68 RabG and other adenovirus serotypes expressing rabies virus glycoprotein. High titers of rabies virus neutralizing antibody (VNA) are elicited after a single dose. The relationship between levels of VNA activity and rabies glycoprotein monomer-binding antibody differs after immunization with adenovirus-vectored vaccines and IRV vaccines, suggesting routes to further enhancement of the efficacy of the adenovirus-vectored candidates. We also demonstrate that ChAdOx2 RabG can be thermostabilised using a low-cost method suitable for clinical bio-manufacture and ambient-temperature distribution in tropical climates. Finally, we show that a dose-sparing effect can be achieved by formulating ChAdOx2 RabG with a simple chemical adjuvant. This approach could lower the cost of ChAdOx2 RabG and other adenovirus-vectored vaccines.Conclusions/ Significance ChAdOx2 RabG may prove to be a useful tool to reduce the human rabies death toll. We have secured funding for Good Manufacturing Practice-compliant bio-manufacture and Phase I clinical trial of this candidate.Author summary Rabies was, after smallpox, the second human disease for which an efficacious vaccine was developed, by Pasteur in 1885. Although it is eminently preventable, with highly efficacious vaccines available for both humans and animals, it still causes considerable mortality in low and middle-income countries. It is a particular problem in areas with the weakest healthcare and veterinary infrastructure, where achieving prompt post-exposure vaccination or high-coverage dog vaccination are challenging.Here, we report the development of a new candidate rabies vaccine, designed to enable low-cost single-dose pre-exposure human rabies prophylaxis in such settings. ChAdOx2 RabG is based upon a simian adenovirus-vectored candidate previously shown to achieve protection after a single dose in non-human primates, now modified to allow clinical-grade bio-manufacture. We show that it induces a potent immune response in mice, that this response can be further enhanced by clinically-relevant adjuvant, and that we can stabilise it such that it can withstand temperatures of up to 45 °C for a month. We will be performing a clinical trial of this candidate in the near future.We are grateful for the assistance of the Jenner Institute Viral Vector Core Facility in the production of adenoviruses, for assistance with ELISA from Kunitaka Yoshida, and for critical review of the manuscript by Adam Ritchie.Author contributionsConceptualization, funding acquisition, project administration, supervision: ADD, RA, HCE, AVSH, SJD, ARF; Investigation: CW, PD, XZ, ZX, HG, AB, ADD; Resources: LB, RV, NC; Writing-original: ADD; Writing-review and editing: All