Differential IL10 mRNA Profiles Associated to Babesia bovis and B. bigemina Infection Levels in Persistently Infected Animals

This work aimed to find quantitative phenotypic traits that can be used to discriminate the levels of resistance/susceptibility to B. bovis and B. bigemina in two groups of cattle presenting the highest (H) or lowest (L) infection levels and Rhipicephalus microplus ticks count. The animals were selected from a previous study of 50 Canchim (5/8 Charolais/zebu) heifers raised in an endemic area for these parasites. These animals were evaluated regarding their TNFα, IL10, IFN-γ, IL12 and iNOS mRNA levels. No differences were found between these groups regarding TNFα, IFN-γ, IL12β or iNOS transcripts. However, the IL10 transcripts were significantly higher in the H group compared to the L group. Moreover, significant correlation coefficients were observed between B. bovis loads and both IL10 and IFN-γ transcripts, while no correlations were found for B. bigemina loads and all tested immune-related transcripts, suggesting that differential IL10 mRNA profiles were closely associated to B. bovis loads. Our results have contributed to a better understanding of the immune responses against Babesia infection, as we demonstrated that the IL10 cytokine levels might also influence or be influenced by parasitemia levels in persistently infected animals.