Development and characterization of new vaccines expressing the rv2626c protein to prevent latent mycobacterium tuberculosis infection

MORELLI MP, AMIANO NO, TATEOSIAN N, MARTIN C, GARCÍA V.; DEL MEDICO ZAJAC MP, CALAMANTE G

Congreso; Reunión Conjunta SAIC. SAI. AAFE. NANOMED-AR; 2021

Tuberculosis (TB) has not been eliminated from any country until now.Moreover, almost 2 billion persons are latently infected with Mycobacterium tuberculosis (Mtb) and at risk of disease reactivation. Thus, new effective vaccines that might prevent TB infection are required. Hence, multi-state vaccines including early secretory antigens plus latency associated antigens from Mtb were proposed. Here, Rv2626c latency antigen was evaluated as a new candidate vaccine by combining a recombinant Modified Vaccinia virus Ankara (MVA) expressing the Rv2626c (MVA2626c) with Rv2626c DNA (DNA vaccine -pCI). Accordingly, Rv2626c DNA was amplified by PCR and ligated into a pCR-TOPO vector. Then, Rv2626c gene was sub-cloned into pCI vector for DNA vaccine (pCI-Rv2626c) or into a transference vector VT (VT-Rv2626c). VT also contains the expression cassette for the β-glucuronidasa enzyme and the flanking sequences of the MVA086R gene (which codifies for the thymidine kinase enzyme). Moreover, VT-Rv2626c was then transfected into CEFs previously infected with wtMVA and recombinant viral clones were subsequently isolated. Then, to evaluate the immunogenicity of these preparations, Balb/c mice were immunized with pCI-Rv2626c/pCI-IL12 (two doses every 14 days). After two weeks, a boost of MVA2626c was administered. Eight days later, splenocytes were obtained and in vitro stimulated with Rv2626c protein. After three days, IFN-γ production and plasma IgG levels were determined by ELISA. Our findings showed that pCI-Rv2626c /MVA2626c induced specific IgG and IFN-γ responses against Rv2626c as compared to non-immunized animals. Furthermore, we observed a significantly increase in IFN-γ (p