Exploring the Ecological Implications of Microbiota Diversity in Birds: Natural Barriers Against Avian Malaria

Natural antibodies (Abs), produced in response to bacterial gut microbiota, drive resistance to infection in vertebrates. In natural systems, gut microbiota diversity is expected to shape the spectrum of natural Abs and resistance to parasites. This hypothesis has not been empirically tested. In this 'Hypothesis and Theory' paper, we propose that enteric microbiota diversity shapes the immune response to the carbohydrate alpha-Gal and resistance to avian malaria. We further propose that anti-alpha-Gal Abs are transmitted from mother to eggs for early malaria protection in chicks. Microbiota modulation by anti-alpha-Gal Abs is also proposed as a mechanism favoring the early colonization of bacterial taxa with alpha 1,3-galactosyltransferase (alpha 1,3GT) activity in the bird gut. Our preliminary data shows that bacterial alpha 1,3GT genes are widely distributed in the gut microbiome of wild and domestic birds. We also showed that experimental infection with the avian malaria parasite P. relictum induces anti-alpha-Gal Abs in bird sera. The bird-malaria-microbiota system allows combining field studies with infection and transmission experiments in laboratory animals to test the association between microbiota composition, anti-alpha-Gal Abs, and malaria infection in natural populations of wild birds. Understanding how the gut microbiome influences resistance to malaria can bring insights on how these mechanisms influence the prevalence of malaria parasites in juvenile birds and shape the host population dynamics.

Automated summary

This paper proposes the hypothesis that gut microbiota diversity shapes the immune response and resistance to avian malaria. The authors also suggest that anti-alpha-Gal antibodies are transmitted from mother to eggs for early malaria protection in chicks. They provide preliminary data showing the presence of bacterial alpha 1,3GT genes in the gut microbiome of birds and the induction of anti-alpha-Gal antibodies upon avian malaria infection.