A metaproteomics approach reveals changes in mandibular lymph node microbiota of wild boar naturally exposed to an increasing trend of Mycobacterium tuberculosis complex infection.

Constraints in the characterization of microbiota community that circulates in the host have limited the extent of co-infection studies in natural populations. In this study, we used a metaproteomics approach to characterize the mandibular lymph nodes microbiota of wild boar (Sus scrofa) naturally exposed to an increasing trend of Mycobacterium tuberculosis complex (MTC) infection. Our results showed a reduction in microbiota diversity and changes in the composition, structure and functionality of the microbiota community associated with an increase in tuberculosis prevalence, from 45% in 2002/06 to 83% in 2009/12. These temporal changes were accompanied by an increase in the relative abundance of Babesia, Theileria and Pestivirus genera and a decrease in the Ascogregarina and Chlorella. A positive association was also evidenced between the prevalence of tuberculosis and the presence of microbial proteins responsible for carbohydrate transport and metabolism. Our findings suggest MTC-host-microbiota interactions at the population level, which may occur in order to ensure sufficient metabolic resources for MTC survival, growth and transmission. We strongly recommend the use of metaproteomics when studying microbiota communities in wildlife populations, for which traditional diagnostic techniques are limited and in which new organisms with a pathogenic potential for domestic animals and humans may appear.