Abstract
Babesiosis poses a serious threat to immunocompromised individuals and the major etiological species of Babesia for human babesiosis is Babesia microti. Merozoites are a critical stage in the life cycle of Babesia microti. Several merozoite proteins have been demonstrated to play important roles in this process; however, most of the merozoite proteins of B. microti remain unknown. In the present study, we identified a novel merozoite protein of B. microti with similar structure to the thioredoxin (Trx)-like domain of the Trx family, which was named as B. microti Trx-like protein (BmTLP). Western blot assays demonstrated that this protein was expressed by B. microti during the erythrocytic infection process, and its expression peaked on day 7 post-infection in vivo. Immunofluorescence assay further showed that this protein is mainly expressed in B. microti merozoites. BmTLP hold both heparin- and erythrocyte-binding properties, which are critical functions of invasion-related proteins. Immunization with recombinant BmTLP imparted significant protection against B. microti infection in mice. Taken together, these results suggest that the novel merozoite protein, BmTLP, is an important pathogenic molecule of B. microti and may be a possible target for the design of babesiosis control strategy.
Highlights
Babesiosis is a parasitic disease of the blood caused by Babesia, a pathogenic protozoon transmitted between humans and animals by hard ticks
We report a novel protein encoded by BMR1_03g03170 in B. microti, which was homologous to PfTrx-like-mero of P. falciparum (Identities: 36%, Figure 1A)
The amino acid sequence of this Babesia protein was found to contain two Trx-like domains (Figure 1C); it was named as B. microti BmTrx-like protein (BmTLP)
Summary
Babesiosis is a parasitic disease of the blood caused by Babesia, a pathogenic protozoon transmitted between humans and animals by hard ticks. Babesia belongs to the phylum Apicomplexa and comprises more than 100 species that infect a wide array of wild and domestic animals, but only few have been shown to infect humans, including B. microti, B. venatorum, B. bovis, B. divergens, B. duncani, B. bigemina, and B. crassa (Gorenflot et al, 1998; Schnittger et al, 2012). Babesiosis poses a serious threat to immunocompromised individuals. B. microti Novel Merozoite Protein common among immunocompromised patients and the elderly (Falagas and Klempner, 1996; Hatcher et al, 2001; Stowell et al, 2007; Krause et al, 2008; Wormser et al, 2010). There is an urgent need to identify new vaccines for effective control of babesiosis
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