Pathogen interactions

Research questions

1) How is the dynamics of each pathogen within a host affected by the other species?

2) Are the interactions symmetrical? What determines the outcome of the interaction?

3) Are the interactions direct or rather mediated by host response?

Description

The geographic mosaic theory of coevolution provides a formal way to consider how ecological and evolutionary processes shape species interactions across environments. The theory suggests that a given interaction between two species may vary from negative, through neutral, to positive, under different ecological conditions. We have previously described negative associations between Mycoplasma and Bartonella within blood samples collected from rodents in the southern part of the western Negev Sand Dunes, but have found positive associations in samples collected from rodents in the northern part. We have manipulated the timing and level of coinfection by the two bacterial species and quantified their temporal dynamics in the rodent hosts and their combined effects on the host’s behavior (activity and anxiety levels), physiology (body temperature, body mass change, and stress hormone levels), and immune response (antibodies quantity) as compared to those resulting from each single infection. This experimental approach allows us to explore the mechanism underlying pathogen interactions, and to test under which conditions the outcomes of these interactions are expected to change.

Relevant publications

Kedem H., C. Cohen, I. Messika, M. Einav, S. Pilosof, Hawlena H. 2014. Multiple effects of host species diversity on co-existing host-specific and host-opportunistic microbes. Ecology 95:1173–1183. https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-0678.1

Cohen, C., M. Einav, and H. Hawlena. 2015. Path analyses of cross-sectional and longitudinal data suggest that variability in natural communities of blood-associated parasites is derived from host characteristics and not interspecific interactions. Parasites & Vectors 8 art 429. https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-015-1029-5

Eidelman, A., C. Cohen, Á. Navarro-Castilla, S. Filler, R. Gutiérrez, E. Bar-Shira, N. Shahar, M. Garrido, S. Halle, Y. Romach, I. Barja, S. Tasker, S. Harrus, A. Friedman, and H. Hawlena. 2019. The dynamics between limited-term and lifelong coinfecting bacterial parasites in wild rodent hosts. Journal of Experimental Biology 222: jeb203562. https://journals.biologists.com/jeb/article/222/15/jeb203562/20321