The effect of Rickettsia bellii on Anaplasma marginale infection in Dermacentor andersoni cell culture

Authors: ASPINWALL, JOSEPH - Washington State University; Jarvis, Sheby; Noh, Susan; BRAYTON, KELLY - Washington State University

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2023
Publication Date: 4/22/2023
Citation: Aspinwall, J.A., Jarvis, S.M., Noh, S.M., Brayton, K.A. 2023. The effect of Rickettsia bellii on Anaplasma marginale infection in Dermacentor andersoni cell culture. Microorganisms. 11(5). Article 1096. https://doi.org/10.3390/microorganisms11051096.
DOI: https://doi.org/10.3390/microorganisms11051096

Interpretive Summary: Anaplasma marginale, a tick-borne pathogen that causes bovine anaplasmosis, affects cattle around the world. Despite broad prevalence and severe economic impacts, limited treatments exist for this disease. Dermacentor andersoni is a the natural vector that transmits A. marginale in the western USA. It was previously demonstrated that D. andersoni that harbor Rickettsia bellii, an endosymbiont, have reduced ability to acquire A. marginale. To confirm and better understand the interaction between A. marginale and R. bellii, we infected tick cell cultures with both bacteria simultaneously and sequentially. We found that A. marginale has reduced ability to infect ticks cells if they are already infected with R. bellii. Though many knowledge gaps remain, this finding may lead to a better understanding of the epidemiology of bovine anaplasmosis and alternative ways to control this disease.

Technical Abstract: Anaplasma marginale is a tick-borne pathogen that causes bovine anaplasmosis, which affects cattle around the world. Despite broad prevalence and severe economic impacts, limited treatments exist for this disease. Our lab previously reported that a high proportion of Rickettsia bellii, a tick endosymbiont, in the microbiome of a population of Dermacentor andersoni ticks, negatively impacts the ticks' ability to acquire A. marginale. To better understand this correlation, we used mixed infection of A. marginale, and R. bellii in D. andersoni cell culture. We assessed the impacts of different amounts of R. bellii in coinfections, as well as established R. bellii infection, on the ability of A. marginale to establish infection and grow in D. andersoni cells. From these experiments, we conclude that A. marginale is less able to establish infection in the presence of R. bellii, and that established R. bellii infection inhibits A. marginale growth.