BABESIA BIGEMINA TICK STAGE SPECIFIC GENES DURING PARASITE DEVELOPMENT WITHIN ADULT FEMALE RHIPICEPHALUS MICROPLUS

Abstract

Babesia bigemina is an intra-erythrocytic parasite that infect cattle and transmitted by tick vectors transovarian transmission. This parasite causes bovine babesiosis (tick cattle fever) and has enormous veterinary, epidemiologically, and economically impact on the cattle industry. Babesia bigemina has a complex life cycle in their vertebrate and tick hosts. Asexual reproduction occurs in the bovine host and sexual reproduction occurs in the tick vectors. When adult female tick feed on an infected bovine host with B. bigemina, they take parasite with blood meal, inside midgut of ticks the parasite transform to sexual stages, they fuse and form zygote. The zygote stage penetrates the epithelial cells of the midgut and transform to kinete. The development and molecular events of this parasite inside the tick remains poorly understood. In this study, we identify a gene (BBBOND_0204030) transcribed by tick stage and contain methyltransferase domain that may play role in B. bigemina gametogenesis. Also, we report a new method to induce B. bigemina sexual stages in vitro using reducing agent Tris 2-carboxyethyl phosphine (TCEP). In addition, we demonstrated protein expression of CCp2, CCp3 and BBBOND_0206730 in B. bigemina kinetes using immunofluorescence assay. BBBOND_0206730 was expressed by B. bigemina kinetes but not by blood stages or in vitro induced sexual stages. Interestingly, bioinformatics analysis showed that this protein was only conserved among transovarially transmitted Babesia species. CCp2 and CCp3 were expressed by induced B. bigemina sexual stages in vitro and B. bigemina kinetes isolated from infected tick hemolymph but not by blood stages. Both proteins were conserved among Babesia and malaria parasites. Together, these candidate proteins and TCEP inducing system may be used to develop and evaluate novel vaccines able to interfere with the development of B. bigemina within the tick vector