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United States Department of Agriculture

Agricultural Research Service

Research Project: Pharmacological and Immunologic Interventions Against Vector-Borne Bovine and Equine Babesiosis

Location: Animal Diseases Research

Title: Acute and persistent infection by a transfected Mo7 strain of Babesia bovis

Authors
item Suarez, Carlos
item Laughery, J -
item Schneider, David
item Sondgeroth, Kerry -
item Mcelwain, Terry -

Submitted to: Molecular and Biochemical Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 26, 2012
Publication Date: May 31, 2012
Repository URL: http://sciencedirect.com/science/article/pii/S0166685112001272
Citation: Suarez, C.E., Laughery, J., Schneider, D.A., Sondgeroth, K.S., Mcelwain, T.F. 2012. Acute and persistent infection by a transfected Mo7 strain of Babesia bovis. Molecular and Biochemical Parasitology. 185(1):52-7.

Interpretive Summary: Stable transfection of the Mo7 strain of Babesia bovis and expression of an exogenous gene has been demonstrated in long term culture. However, the use of transfected parasites as marker vaccines or vehicles for expressing exogenous antigens in vivo requires demonstration of acute and persistent infection, as well as stability and expression of the transgene. In this study, a Mo7-derived B. bovis line stably transfected with the gfp-bsd gene was inoculated into two, three month old calves, while two additional age-matched calves were inoculated with wild type Mo7 strain parasites. All inoculated animals developed similar mild clinical signs at 7 or 8 days post inoculation (dpi) characteristic of acute babesiosis caused by the Mo7 strain. Transfusion of 50 ml of blood from all experimentally infected calves into four naïve splenectomized calves at 212 dpi resulted in acute disease in recipients, confirming persistent infection in the four donor animals. Parasites expressing GFP were established in cultures initiated from a recipient calf, and PCR and sequence analysis demonstrated that the sequences of the transfected genes in transfected parasites remain unaltered. These data demonstrate the feasibility of using transfected genes as molecular markers to differentiate B. bovis vaccinated from infected animals, and confirm that exogenous transgenes can be expressed and remain stable throughout acute and persistent infection.

Technical Abstract: Stable transfection of the Mo7 strain of Babesia bovis and expression of an exogenous gene has been demonstrated in long term culture. However, the use of transfected parasites as marker vaccines or vehicles for expressing exogenous antigens in vivo requires demonstration of acute and persistent infection, as well as stability and expression of the transgene. In this study, a Mo7-derived B. bovis line stably transfected with the gfp-bsd gene was inoculated into two, three month old calves, while two additional age-matched calves were inoculated with wild type Mo7 strain parasites. All inoculated animals developed similar mild clinical signs at 7 or 8 days post inoculation (dpi) characteristic of acute babesiosis caused by the Mo7 strain. B. bovis rap-1 was detected in the bloodstream by nested PCR at 4 dpi, and consistently throughout the ten month test period in all animals. Transcripts of the transfected gfp-bsd gene were detected at 45 and 52 dpi. Transfusion of 50 ml of blood from all experimentally infected calves into four naïve splenectomized calves at 212 dpi resulted in acute disease in recipients, confirming persistent infection in the four donor animals. Parasites expressing GFP were established in cultures initiated from a recipient calf, and PCR and sequence analysis demonstrated that the sequences of the transfected genes in transfected parasites remain unaltered. Taken together these data demonstrate the feasibility of using transfected genes as molecular markers to differentiate B. bovis vaccinated from infected animals, and confirm that exogenous transgenes can be expressed and remain stable throughout acute and persistent infection.

Last Modified: 10/24/2014
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