A transfected Babesia bovis parasite line expressing eGFP is able to complete the full life cycle of the parasite in mammalian and tick hosts

Authors: JOHNSON, WENDELL - Retired ARS Employee; HUSSEIN, HALA - Washington State University; CAPELLI-PEIXOTO, JANAINA - Washington State University; LAUGHERY, JACOB - Washington State University; Taus, Naomi; Suarez, Carlos; Ueti, Massaro

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2022
Publication Date: 5/27/2022
Citation: Johnson, W.C., Hussein, H.E., Capelli-Peixoto, J., Laughery, J.M., Taus, N.S., Suarez, C.E., Ueti, M.W. 2022. A transfected Babesia bovis parasite line expressing eGFP is able to complete the full life cycle of the parasite in mammalian and tick hosts. Pathogens. 11(6). Article 623. https://doi.org/10.3390/pathogens11060623.
DOI: https://doi.org/10.3390/pathogens11060623

Interpretive Summary: Bovine babesiosis is caused by tick-borne pathogens of the genus Babesia, including B. bovis. This protozoan parasite has a complex life cycle involving dynamic changes to its transcriptome during transition between the invertebrate and vertebrate hosts. Studying the role of upregulated genes by tick stage parasites has been hindered by the lack of appropriate tools to study parasite gene products in the invertebrate host. This work describes tfBbo5480, a transfected B. bovis cell line, constitutively expressing enhanced green fluorescent protein (eGFP) created by a whole gene replacement transfection strategy, that is capable of completing the parasites entire life cycle in both the vertebrate and invertebrate hosts. tfBbo5480 was demonstrated to respond to in vitro sexual stage induction and upon acquisition by the female tick vector, Rhipicephalus microplus, the tick specific kinete stage of tfBbo5480 was visualized by epifluorescence microscopy. Larvae from tfBbo5480 exposed R. microplus female ticks successfully transmitted the transfected parasite to a naïve calf. The development of the whole gene replacement strategy will permit a deeper understanding of the biology of parasite-host-vector triad interactions and facilitate the evaluation of upregulated genes during the parasites journey through the tick vector leading to new intervention strategies for the control of bovine babesiosis.

Technical Abstract: Bovine babesiosis is caused by apicomplexan pathogens of the genus Babesia, including B. bovis. This protozoan parasite has a complex life cycle involving dynamic changes to its transcriptome during transition between the invertebrate and vertebrate hosts. The study of the role of upregulated genes by tick stage parasites has been hindered by the lack of appropriate tools to study parasite gene products in the invertebrate host. Herein, we present tfBbo5480, a transfected B. bovis cell line, constitutively expressing enhanced green fluorescent protein (eGFP) created by a whole gene replacement transfection strategy that is capable of completing the parasites entire life cycle in both the vertebrate and invertebrate hosts. tfBbo5480 was demonstrated to respond to in vitro sexual stage induction and upon acquisition by the female tick vector, Rhipicephalus microplus, the tick specific kinete stage of tfBbo5480 was visualized by epifluorescence microscopy. Larvae from tfBbo5480 exposed R. microplus female ticks successfully transmitted the transfected parasite to a naïve calf. The development of the whole gene replacement strategy will permit a deeper understanding of the biology of parasite-host-vector triad interactions and facilitate the evaluation of upregulated genes during the parasites journey through the tick vector leading to new intervention strategies for the control of bovine babesiosis.