Effect of age at Vaccination on Immunological Response to Recombinant MAP Subunit Vaccine: Abstract in journal

Neonates are more susceptible to Mycobacterium avium subsp. paratuberculosis (MAP), the agent of Johne’s disease, due to high degree of exposure from their dams and possibly less developed immune system. Thus an effective vaccine should not only elicit strong immune response in young animals, but also a quality of the T-cell response that correlates with long term protection. Here we report the effect of age at vaccination and quality of immune response following vaccination of calves with recombinant MAP proteins formulated with DDA/ TDB (CAF01) adjuvant. A total of 27 male jersey calves were divided into three groups of nine calves each with first vaccination at 2, 8 and 16 weeks of age, respectively. Vaccine induced immune response, mainly the Th1 type cytokine secretion, was evaluated in different age groups following booster doses at equal time intervals. Preliminary results show higher antigen specific IFN-c levels in response to heat shock protein and ESAT-6 family member protein antigens. It was observed that there was no effect of age on the IFN-c producing capacity of the animals in the different age groups after stimulation of whole blood with SEB. However, animals in the older age group responded well to the MAP multi-antigens and might need only one booster compared to the younger animals. Findings from this work could be interesting to determine the appropriate age of vaccination so as to generate the memory T cell pool and for MAP vaccine challenge experiments.