The dynamics between limited-term and lifelong coinfecting bacterial parasites in wild rodent hosts

Abstract

Interactions between coinfecting parasites may take various forms, either direct or indirect, facilitative or competitive, and may be mediated by either bottom-up or top-down mechanisms. Although each form of interaction leads to different evolutionary and ecological outcomes, it is challenging to tease them apart throughout the infection period. To establish the first step towards a mechanistic understanding of the interactions between coinfecting limited-term bacterial parasites and lifelong bacterial parasites, we studied the coinfection of Bartonella sp. (limited-term) and Mycoplasma sp. (lifelong), which commonly co-occur in wild rodents. We infected Bartonella-and Mycoplasma-free rodents with each species, and simultaneously with both, and quantified the infection dynamics and host responses. Bartonella benefited from the interaction; its infection load decreased more slowly in coinfected rodents than in rodents infected with Bartonella alone. There were no indications for bottomup effects, but coinfected rodents experienced various changes, depending on the infection stage, in their body mass, stress levels and activity pattern, which may further affect bacterial replication and transmission. Interestingly, the infection dynamics and changes in the average coinfected rodent traits were more similar to the chronic effects of Mycoplasma infection, whereas coinfection uniquely impaired the host's physiological and behavioral stability. These results suggest that parasites with distinct life history strategies may interact, and their interaction may be asymmetric, non-additive, multifaceted and dynamic through time. Because multiple, sometimes contrasting, forms of interactions are simultaneously at play and their relative importance alternates throughout the course of infection, the overall outcome may change under different ecological conditions.

Pathogen community composition and co-infection patterns in a wild community of rodents

“…infections in My. glareolus , corroborating negative interactions reported in co-infection experiments in gerbils (Eidelman et al . 2019).…”

“…There remain additional important limits to the interpretation of snapshot observational studies from wild populations such as ours. For instance, they can not provide information about the sequence or duration of infection, although these features strongly affect the outcome of within-host interactions (Eidelman et al . 2019).…”

“…2017), and both positive (Kedem et al . 2014; Eidelman et al . 2019) and negative (Cohen, Einav & Hawlena 2015) associations between Bartonella spp.…”

“…2014; Volokhov et al . 2017)); iii) associations between Bartonella and hemotropic Mycoplasma species (both positive and negative associations, as well as experimental demonstration of dynamic interactions, have been described in Gerbillus andersonii (Eidelman et al . 2019)).…”

Non-Invasive Monitoring of Adrenocortical Activity in Three Sympatric Desert Gerbil Species

“…These three gerbils, as other wildlife species, can be also affected by other environmental and human factors acting as stressors [ 6 , 7 , 8 , 9 , 10 , 11 ]. However despite the great importance of understanding physiological aspects of wild animals, the few available works have been carried out only in G. andersoni [ 35 , 36 , 37 , 38 ] and G. pyramidum [ 16 , 36 ] and, as far as we know, currently there is no work addressing physiological stress responses in G. gerbillus nor is there any comparing physiological stress responses among these three sympatric species.…”