Oral re-vaccination of wild boar with BCG yields a strong protective response against challenge with a field strain, and re-vaccination of wild boar with BCG is not counter-productive. These findings are relevant given that re-vaccination is likely to happen under real (field) conditions.

These are the main conclusions by Christian Gortazar of SaBio IREC in Ciudad Real, Spain and co-authors of a paper published in BMC Veterinary Research.

They explain that field vaccination trials with Mycobacterium bovis BCG, an attenuated mutant of M. bovis, are ongoing in Spain, where the Eurasian wild boar (Sus scrofa) is regarded as the main driver of animal tuberculosis (TB).

The oral baiting strategy involves deploying vaccine baits twice each summer in order to gain access to a high proportion of wild boar piglets.

The aim of this study was to assess the response of wild boar to re-vaccination with BCG and to subsequent challenge with an M. bovis field strain.

BCG re-vaccinated wild boar had a 75.8 per cent lower lesion score and a 66.9 per cent lower culture score than unvaccinated controls.

Only one of nine vaccinated wild boar had a culture-confirmed lung infection, as compared to seven of the eight unvaccinated controls.

Serum antibody levels were highly variable and did not differ significantly between BCG re-vaccinated wild boar and controls.

Gamma IFN levels differed significantly between BCG re-vaccinated wild boar and controls.

The mRNA levels for IL-1b, C3 and MUT were significantly higher in vaccinated wild boar than the controls after vaccination and they decreased after mycobacterial challenge.

Reference

Gortazar C., B. Beltrán-Beck, J.M. Garrido, A. Aranaz, I.A. Sevilla, M. Boadella, K.P. Lyashchenko, R.C. Galindo, V. Montoro, L. Domínguez, R. Juste and J. de la Fuente16. 2014. Oral re-vaccination of Eurasian wild boar with Mycobacterium bovis BCG yields a strong protective response against challenge with a field strain. BMC Veterinary Research. 10:96. doi:10.1186/1746-6148-10-96