Associação do polimorfismo na 3’ UTR do gene IFN-γ com seu padrão de expressão gênica e do miRNA 125b no sangue de búfalas leiteiras com e sem hemoparasitoses.

Abstract

The use of genetic markers as well as the determination of the expression of genes involved in the immune system of buffaloes is of extreme value in selection programs, as they can promote the choice of animals resistant to many pathogens. The aim of the study was to associate the polymorphism g4467 G>A in the INF-γ gene with its gene expression profile as well as miRNA 125b in dairy buffaloes with hemoparasitoses. Blood samples were collected from 145 buffaloes for DNA extraction using the phenolchloroform method, followed by PCR and RT-PCR techniques for molecular diagnosis of Babesia spp. Trypanosoma vivax and Anaplasma marginale, respectively. All animals were genotyped using the PCR-RFLP technique. Then, the total RNA of the animals of different genotypes was extracted to determine the expressions of INF-γ and miRNA 125b through RT-PCR. All buffaloes were negative for Babesia spp. and A. marginale and only 12 were positive for T. vivax. PCRRFLP revealed three band patterns for the studied SNP. Where the GG, GA and AA genotypes were observed, in the proportions 3.4%, 2.1% and 94.5% respectively and the most frequent A allele (95.5%). The SNP showed deviation from the Hardy-Weinberg Equilibrium (EHW) (P<0.05) and deficit of heterozygotes with FIS 0.759. All animals of the genotypes found showed expression for both genes, except for the positive GG, which was not detected. The INF-γ expression profile was higher in GA and GG negative and AA positive genotypes. However, the miRNA 125b expression profile was lower for the positive AA and GA genotypes and higher for the three negative genotypes. Thus, the results suggest that the SNP evaluated in the population showed low variability because it is a dairy herd that is probably under selection pressure and that AA-positive buffaloes, even if asymptomatic for T. vivax, may be susceptible to infection due to higher expression of INF-γ and lower expression of miRNA 125b. However, buffaloes GG and GA negative for having higher levels of expression for both genes can be considered genetically resistant to infection by T. vivax.