IMMUNIZATION SCHEDULES AND AVIDITY ASSAY AGAINST RESPIRATORY BOVINE DISEASE BACTERIA IN CATTLE

DIAZ AILEN; ALMOZNI BRENDA; SOTELLO AGUSTINA; MANGONE FRANCO; CANELLADA ANDREA; CASTRO MARISA

Buenos Aires

Congreso; Reunion conjunta de Sociedades de Biociencias; 2017

Livestock production is exposed to many adverse conditions whichthreaten animal health as the Respiratory Bovine Disease (RBD). Althoughcommercial vaccines are employed, protective immune responses are not wellunderstood and immunodiagnostic methods are not well defined. This work aimed toemploy an indirect in-house ELISA and develop an avidity assay to study bovineimmune response against the bacterial agents: Pasteurella multocida (PM), Mannheimiahaemolytica (MH), Histophilus somni (HS).Freshly weaned 2-month calves were employed in 2 different immunization schedules.The 1st plan (n=10) received 3 doses (every 21days) of the commercial vaccine BiopoligenHS (CV) or an experimental vaccine(EV) formulated with inactivated culture supernatant of PM and aluminum. The 2ndplan (n=7) was immunized with 2 doses (days 0 and 21) employing the CV or an EVeither with PM or MH formulated with a polymeric adjuvant, Montanide Gel01. Acontrol cow inoculated only with adjuvant was included in both schedules. Calveswere bled on days 0, 21, 42 and 60, depending the schedule. Specific IgGand IgM were measured by ELISA, and for the avidity assay an adaptation wastested employing urea as dissociating agent. In the 1st plan, IgG levels were higher for CV compared to PMsupernatant and with the placebo (p<0,05). Avidity assay showed differencesbetween immunized groups and placebo (p<0,05). In the 2nd plan, Montanidegroup showed higher tendency IgG levels against PM and MH than the CV (ns). PMMontanide showed higher avidity index than the rest (p<0,05). Surprisingly,anti-HS IgG of vaccinated calves were similar to control cows. No differenceswere observed in IgM levels for the 3 bacteria in any plan. Our results showthat different formulations and immunization schedules could be used to improvethe immune response against bacteria causing BRD.Analyzing bovine immune response would help to understand how vaccinescould be modified and reduce new RBD outbreaks.