Studies in both humans and model organisms suggest that the microbiome may play a significant role in host health, including digestion and immune function. Microbiota can offer protection from exogenous pathogens through colonization resistance, but microbial dysbiosis in the gastrointestinal tract can decrease resistance and is associated with pathogenesis. Little is known about the effects of potential pathogens, such as Salmonella, on the microbiome in wildlife, which are known to play an important role in disease transmission to humans. Culturing techniques have traditionally been used to detect pathogens, but recent studies have utilized high throughput sequencing of the 16S rRNA gene to characterize host-associated microbial communities (i.e., the microbiome) and to detect specific bacteria. Building upon this work, we evaluated the utility of high throughput 16S rRNA gene sequencing for potential bacterial pathogen detection in barn swallows (Hirundo rustica) and used these data to explore relationships between potential pathogens and microbiota. To accomplish this, we first compared the detection of Salmonella spp. in swallows using 16S rRNA data with standard culture techniques. Second, we examined the prevalence of Salmonella using 16S rRNA data and examined the relationship between Salmonella-presence or -absence and individual host factors. Lastly, we evaluated host-associated bacterial diversity and community composition in Salmonella-present vs. -absent birds. Out of 108 samples, we detected Salmonella in six (5.6%) samples based on culture, 25 (23.1%) samples with unrarefied 16S rRNA gene sequencing data, and three (2.8%) samples with both techniques. We found that sex, migratory status, and weight were correlated with Salmonella presence in swallows. In addition, bacterial community composition and diversity differed between birds based on Salmonella status. This study highlights the value of 16S rRNA gene sequencing data for monitoring pathogens in wild birds and investigating the ecology of host microbe-pathogen relationships, data which are important for prediction and mitigation of disease spillover into domestic animals and humans.
Bibliographical noteFunding Information:
This research was funded by National Science Foundation grant #1617982 to WG, RB, and PK, United States-Israel Binational Science Foundation grant: 2015904 to RN and WG, and USDA-National Institute of Food and Agriculture Hatch Project: ME021908 through the Maine Agricultural and Forest Experimentation Station to PK.
We would like to thank members of the Movement Ecology Lab at the Hebrew University of Jerusalem for assistance with sample collection, especially Yoav Bartan for his help in the field as well as the lab. All fieldwork was conducted using permit number 2017/41764 by the Israel National Protection Authority and approved by an ethics committee according to institutional and national guidelines. We thank Candace Wang, Hannah Newcombe, and Lydia Smith for assistance with laboratory work, and the Wildlife Disease Genetics Laboratory at the University of Maine for feedback on the manuscript. This is Maine Agricultural and Forest Experiment Station Publication no. 3853.
© Copyright © 2021 Choi, Corl, Wolfenden, Lublin, Ishaq, Turjeman, Getz, Nathan, Bowie and Kamath.
- 16S rRNA sequencing
- barn swallows
- disease surveillance