BmVDAC upregulation in the midgut of Rhipicephalus microplus, during infection with Babesia bigemina.

The molecular mechanisms involved during the infection of Rhipicephalus microplus midgut cells by Babesia bigemina are of great relevance and currently unknown. In a previous study, we found a voltage-dependent anion channel (VDAC)-like protein (BmVDAC) that may participate during parasite invasion of midgut cells. In this work, we investigated BmVDAC expression at both mRNA and protein levels and examined BmVDAC localization in midgut cells of ticks infected with B. bigemina at different times post-repletion. Based on the RT-PCR results, Bmvdac expression levels were significantly higher in infected ticks compared to uninfected ones, reaching their highest values at 24h post-repletion (p<0.0001). Similar results were obtained at the protein level (p<0.0001). Interestingly, BmVDAC immunolocalization showed that there was an important differential expression and redistribution of BmVDAC protein between the midgut cells of infected and uninfected ticks, which was more evident 24h post-repletion of infected ticks. This is the first report of BmVDAC upregulation and immunolocalization in R. microplus midgut cells during B. bigemina infection. Further studies regarding the function of BmVDAC during the infection may provide new insights into the molecular mechanisms between B. bigemina and its tick vector and could result in its use as an anti-tick and transmission-blocking vaccine candidate.