Over the past decade, advances in high-throughput sequencing technology have revolutionized our understanding of host-associated microbiomes, revealing multiple associations between microbiome composition and host health and behavior. Understanding of microbiome assembly, dynamics, and causal relationships with host health remains limited, however, despite the wealth of metagenomic data now available. There is a need for detailed longitudinal studies that track changes in microbiome composition over time and simultaneously track host physiology/immunity, behavior, and health so that causal relationships can be drawn between the host and the microbiome. The objectives of this study are to describe (1) the impacts of host traits (age, sex, relatedness, and behavior) on the nasal microbiome in a natural host population, and (2) the relationship between the nasal microbiome and incidence of respiratory infections. To address these questions, we analyzed sequence data from nasal microbiome swabs obtained from an intensively-studied herd of semi-wild African buffalo taken at 2-3 month intervals over the course of one year, in conjunction with detailed health, behavioral, and genetic data from the herd.
Preliminary analysis of the relationship between host traits and microbiome community show intriguing results. Intra-individual variation in nasal microbiome richness and diversity decrease over time as the animal ages, especially within the first year of life. This suggests that the nasal microbiome community is relatively unstable after initial colonization, and then becomes more stable over time. Nasal microbiome diversity, richness, and relative taxa abundances fluctuate significantly across seasons, possibly due to behavioral and physiological changes that are related to reproductive timing, or due to seasonal changes in environmental conditions and resource availability. Initial analysis of behavioral data shows that there is inter-individual variation in social contacts and habitat preferences, but the relationships between behavior and nasal microbiome have not yet been analyzed.
Initial exploration of the relationship between respiratory infection and nasal microbiome also suggest several interesting patterns. Bovine respiratory syncytial virus (BRSV) incidence appears to correlate with a decrease in nasal microbiome evenness, suggesting that BRSV is either a cause or a consequence of disruptions in the balance of the nasal microbiome community. Infection with Bovine Tuberculosis (BTB) appears to influence relative abundances of resident microbes. Although not yet conclusive, these results offer promising evidence that the nasal microbiome may be significant in ecologically and economically important respiratory diseases.