Experimental infection of calves with transfected attenuated Babesia bovis expressing the Rhipicephalus microplus Bm86 antigen and eGFP marker: Preliminary studies towards a dual anti-tick/Babesia vaccine

Authors: MAZUZ, MONICA - Kimron Veterinary Institute; LAUGHERY, JACOB - Washington State University; LEBOVITZ, BENJAMIN - Kimron Veterinary Institute; YASUR-LANDAU, DANIEL - Kimron Veterinary Institute; ROT, ASSAEL - Kimron Veterinary Institute; BASTOS, REGINALDO - Washington State University; EDERY, NIR - Kimron Veterinary Institute; FLEIDEROVITZ, LUDMILA - Kimron Veterinary Institute; LEVI, MAAYAN - Kimron Veterinary Institute; Suarez, Carlos

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2021
Publication Date: 1/29/2021
Citation: Mazuz, M.L., Laughery, J.M., Lebovitz, B., Yasur-Landau, D., Rot, A., Bastos, R.G., Edery, N., Fleiderovitz, L., Levi, M.M., Suarez, C.E. 2021. Experimental infection of calves with transfected attenuated Babesia bovis expressing the Rhipicephalus microplus Bm86 antigen and eGFP marker: Preliminary studies towards a dual anti-tick/Babesia vaccine. Pathogens. 10(2). Article 135. https://doi.org/10.3390/pathogens10020135.
DOI: https://doi.org/10.3390/pathogens10020135

Interpretive Summary: Bovine babesiosis, caused by hemoparasites Babesia bovis and B. bigemina, is a major tick-borne disease of cattle with a global economic impact. Bovine babesiosis can be prevented using attenuated Babesia vaccines, babesicidal drugs, control of ticks, or a combination of these measures. Attenuated Babesia vaccines help by mitigating acute disease but have several constraints, including development of persistent infections, posing challenges to distinguish vaccinated from naturally infected cattle. Vaccination of cattle with the Rhipicephalus microplus Bm86 based vaccine is effective in reducing fitness of R. microplus and R. annulatus, among other tick species, but several booster inoculations are required to maintain protective levels of antibodies. This is the first report of transfected B. bovis expressing the protective tick antigen Bm86. Results represents a proof of concept for a novel live, attenuated, tagged dual-vaccine to attempt simultaneous control of bovine babesiosis and tick infestation.

Technical Abstract: Bovine babesiosis, caused by Babesia bovis and B. bigemina, is a major tick-borne disease of cattle with global economic impact. The disease can be prevented using integrated control measures including attenuated Babesia vaccines, babesicidal drugs and tick control approaches. Vaccination of cattle with the Rhipicephalus microplus Bm86-based recombinant vaccine reduces fitness of R. microplus and R. annulatus, but several booster inoculations are required to maintain protection. Herein we generated a stable transfected strain of B. bovis expressing enhanced GFP (eGFP) and a chimeric version of Bm86 (B. bovis/Bm86/eGFP). The eGFP was expressed in the parasite cytoplasm, whereas Bm86 was displayed on the surface of merozoites. Three splenectomized calves experimentally infected with B. bovis/Bm86/eGFP showed mild signs of acute disease and developed long-lasting antibody responses to B. bovis and native Bm86. No evidence of sequestration of parasites in the cerebral capillaries was found upon post-mortem analysis, confirming attenuation of the strain. This is the first report of transfected B. bovis expressing the tick antigen Bm86 on the merozoite surface that elicits an antibody response to native Bm86. These results represent a proof of concept for a novel live, attenuated, tagged dual-vaccine approach to attempt simultaneous control of babesiosis and tick infestation.