Recombinant Modified Vaccinia Virus Ankara expressing rabies glycoprotein induces protection against challenge in mice

GARANZINI DEBORA ; MICUCCI MATIAS PÉREZ OSCAR ; DEL MÉDICO ZAJAC MARÍA PAULA; CALAMANTE GABRIEL

CABA

Congreso; Rabies in the Americas (RITA) 2018; 2018

Fundación Cassará

Inactivated vaccines against rabies are effective but present several disadvantages such as uncertain antigen composition, manipulation of the pathogen during the vaccine manufacturing, need of cold chain during storage and transportation and inability to differentiate vaccinated from infected animals. To overcome these inconveniences, the actual tendency is the rational design of recombinant immunogens (viral vectored or subunit vaccines) that are safe and efficacious against pathogens. The aim of this work is the development and evaluation of an anti-rabies vaccine candidate based on recombinant Modified vaccinia Ankara Virus (MVA).In order to obtain recombinant MVA viruses we constructed a transfer vector (VT-GUS/RG) carrying the coding sequence of rabies glycoprotein (RG) flanked by genomic regions of the MVA086R gene to allow in vivo recombination. Recombinant MVA viruses expressing RG protein were obtained by transfecting VT-GUS/RG into primary cultures of chicken embryo fibroblast (CEFs) previously infected with MVA. Recombinant MVA-RG was isolated based on its capacity to produce blue-plaques in the presence of b-glucoronidase (GUS) substrate. The presence and expression of RG coding sequence was confirmed by PCR and Western blot, respectively. Then, BalB/C mice were inoculated twice with recombinant or non-recombinant MVA vectors and specific immune response was evaluated by ELISA. The immunization with MVA-RG induces anti-rabies antibodies that increased after the boost and remained stable for at least five month. The IgG2a/IgG1 ratio was 2.72 indicating a Th1-immune response. Next, the protection induced by MVA-RG was evaluated in mice intra-cerebrally infected with rabies virus, at 14 days or 5 months after the second immunization. The percentage of protection was 60 and 80%, respectively. In this work we obtained a recombinant MVA vector that express RG protein. Besides we demonstrated that MVA-RG induces long lasting immune responses that protect mice against rabies virus challenge.