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Individual variability of vaccine response can weaken the level of protection of a herd. Identifying and predicting the causes are ways research can improve health and welfare on farms.

The intestinal microbiota interacts with the immune system via its host. Our study was aimed at analyzing the relation with the intensity of vaccine response in pigs vaccinated against IAV. The animals were vaccinated upon weaning at 28 days of age (J28), with a challenge three weeks later. Their immune responses to vaccination were followed by specific antibody assays and hemaglutination tests at different times:  early (on the day of challenge), at the peak of response (1 to 2 weeks after the challenge) and before slaughter between 140 and 150 days of age (long-term persistance of antibodies). The microbiota was characterized by sequencing of the RNAr 16S gene from fecal DNA and analysis of operational taxonomics units (OTU).

We observed a higher pre-vaccination microbial richness of the fecal microbiota in high responders to the vaccine compared to low responders with an overabundance of Prevotella and Muribaculaceae genera OTU. On the contrary, lower responders presented a higher abundancy of  Helicobacter Bacteroides, Christensenellaceae R7-group, Succinivibrio and Escherichia-Shigella genera OTU. These bacterial genera suggest that the associations identified implicate mechanisms associated with free fatty acid synthesis favoring the stimulation of the immune system or LPS with variable immunomodulating properties. At day 28, we also identified a group of 81 OTU predictors of response peak intensity. 

These promising results must undergo additional studies before they can be used in vaccination protocols.

Bibliography:
Borey M, Blanc F, Lemonnier G, Leplat J-J, Jardet D, Rossignol M-N, Ravon L, Billon Y, Bernard M, Estellé J, Rogel-Gaillard C. Links between fecal microbiota and the response to vaccination against influenza A virus in pigs. npj Vaccines 6, 92 (2021). https://doi.org/10.1038/s41541-021-00351-2

Contact :

• Marion Borey (marion.borey(at)inrae.fr)
• Claire Rogel-Gaillard (claire.rogel-gaillard(at)inrae.fr)