Potentiation of the immune response elicited by a commercial vaccine against Bovine Respiratory Disease (BRD) employing an immunomodulator in a murine model

ALMOZNI B; DÍAZ AM; MANGONE F; SOTELO A; CANELLADA AM; CASTRO M

Mar del Plata

Congreso; LXVI Reunión Anual de la Sociedad Argentina de Inmunología; 2018

Sociedad Argentina de Inmunología

BRD is a multi-factorial disease that causes high morbidity and mortality in cattle. BRD etiology is composed by viruses and bacteria: Mannheimia haemolytica (MH), Pasteurella multocida (PM), Histophilus somni (HS). Although BRD vaccines are worldwide utilized, there is a need of new therapeutic-adjuvant strategies in order to minimize the disease impact. Propionibacterium acnes (Pa) is a Gram-positive anaerobic bacillus and it is used as a heat-killed suspension for treatment of non-specific respiratory disease in horses because it has beneficial immunomodulatory activity. This work aimed to evaluate the effect of Pa on the humoral and cellular immune response elicited by a commercial BRD vaccine.BALB/c mice were subcutaneously (sc) injected with P. acnes (350 μg or 500 μg/animal) on days -7, 10 and 21. The BRD immunization was performed on days 0, 15 and 27 by sc injection. Blood samples were obtained on days 0, 10, 27 and day 38 when animals were sacrificed. Control group received the commercial vaccine. Serum specific antibody levels (IgG, IgG1, and IgG2a anti-PM, MH and HS), and cytokines in spleen supernatants, were determined by ELISA.At final day, BRD immunization induced specific IgG titers and the production of IFNg, in all immunized mice. Treatment with Pa increased anti-PM IgG levels anti PM (p< 0,001) and IgG2a for MH, PM and HS (p< 0,05). In relation with anti-MH and HS IgG and IgG1, antibody levels in Pa treated-mice were higher than the immunized control group, although without reaching a statistical significance.These results indicate that the administration of P. acnes was able to enhance the response elicited by a BRD vaccine, so it could be used as an adjuvant strategy to potentiate weak immune responses.