Clinical trial (phase 1) of vaccination with a heat-killed local strain of Mycobacterium avium subsp. paratuberculosis

MOYANO RD; COLOMBATTI OLIVIERI MA; NAGEL A; CUERDA X; GRAVISACO M. J.; ALVARADO PINEDO, F.; SOSA P.; TRAVERIA GE; ALONSO N.; ROMANO MI

Dublin

Congreso; ICP2022; 2022

International association for paratuberculosis

Paratuberculosis (PTB) is a chronic disease caused by Mycobacterium avium subsp. paratuberculosis and causes serious economic losses. Its control and 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 and the evaluation of its interference with bovine tuberculosis diagnosis in a herd with a high prevalence of PTB.We used three groups of 46 calves (1-2 months of age): 1) Silirum vaccine, 2) local strain inactivated with adjuvant Montanide ISA 201 (Seppic SA) and 3) unvaccinated group. Serum samples were taken at 2, 4-5, 10-12, and 22 months post-vaccination (mpv) for the measurement of antibodies. At 4-5 mpv whole blood was extracted to evaluate lymphocyte populations (CD4, CD8, WC1, CD335, co-marked with CD25 and IFNg) and an in-vitro infection of PBMC as performed (microbicide assay). In addition, the intradermal reaction with PPDa and PPDb were evaluated.The group vaccinated with the local strain presented a higher and earlier (IgG) humoral immune response (with higher antibody titre at 4-5 mpv) and it was the only group that presented a significant response, with production of IFNg, from CD4, CD8, WC1 and NK cells (CD335). In the microbicide assay, no significant differences were observed. Vaccination did not yield false positive results for the official diagnosis (skin test) of bovine tuberculosis after 12 mpv.The results indicate that the vaccine with the inactivated local strain induces a humoral and cellular immune response, slightly higher than that induced by the commercial vaccine