Immune response induced by a heat-killed Mycobacterium avium subsp. paratuberculosis vaccine of a local strain in animals models.

COLOMBATTI OLIVIERI, MARÍA ALEJANDRA; ROBERTO DAMIÁN MOYANO; GRAVISACO MARIA JOSE; MARIA LAURA MON; TRAVERIA, GABRIEL EDUARDO; MARIA DE LA PAZ SANTANGELO; DELGADO FERNANDO; ROMANO MARIA ISABEL

Cancun

Congreso; 14th International Colloquium on Paratuberculosis; 2018

International Association for Paratuberculosis

Paratuberculosis is a chronic disease caused by Mycobacterium avium subsp. paratuberculosis (Map) and causes serious economic losses. Its control and the development of an effective vaccine are essential. The aim of this study is the evaluation of the immune response induced by a virulent local strain inactivated vaccine in mice and cattle in order to find a better vaccine candidate.Mouse model: 3 groups of 15 female BALB/c mice A) unvaccinated control, B) Silirum vaccine, C) inactivated local strain with incomplete Freund´s adjuvant. Two vaccine doses of 0.2 ml (2.5 mg dry bacteria pellet /ml) was administered subcutaneously with a difference of 15 days. One month after the last vaccine dose we proceeded to the intraperitoneally challenge with 1x108 CFU of a virulent Map strain. At pre-challenge cytokines and IgG were measured, and at 6 and 12 weeks post-challenge the animals were sacrificed and the spleen was taken for counting UFC and liver for histopathology. Bovine model: 3 groups of 5 calves (1-2 months of age): 1) Silirum vaccine, 2) local strain inactivated with adjuvant Montanide (Seppic SA) and 3) unvaccinated group. Serum samples were taken monthly for the measurement of antibodies and every 2 months whole blood was extracted to measure cytokines and lymphocyte populations. Also the intradermal reaction with PPDa and PPDb was evaluated.In the mice model, the groups with the local strain inactivated vaccine obtained CFU counts and score lesion were lower than the control group. The immune response was predominantly humoral (IgG1) and a cellular response was also detected with production of IFNg, IL-6 and IL-2 in both vaccinated groups. In cattle the immune response was higher (IgG and IFNg) for the group vaccinated with the local strain and there were no reactors to PPDb in the intradermal reaction.The results indicate that the vaccine with the inactivated local strain protects in the murine model and induces a humoral and cellular immune response, slightly higher than that induced by the commercial vaccine in both animal models.