Search

The Authors investigated polymorphism of the bovine BoLA‑DRB3 gene in connection with resistance or susceptibility to brucellosis of two Kazakh meat breeds, Auliekol and Kazakh Whiteheaded breeds, using PCR‑RFLP. In Auliekol cattle (n = 158), 22 alleles were detected in the brucellosis group, and 24 alleles were shown in the healthy group. BoLA-DRB3 alleles *3, *4, *19, *21 were more common in healthy animals, while Brucella‑positive cattle were more frequently carriers of alleles *7, *10, *18. In Kazakh Whiteheaded cattle (n = 146), 21 alleles were detected in infected and 23 alleles in healthy cattle. Alleles *3, *8, *21 significantly predominate in healthy cattle, while alleles *7, *11, *16 are typical for animals with brucellosis. This study identified BoLA-DRB3 alleles associated with genetic resistance (*3 and *21) and susceptibility (*7) to brucellosis; remarkably, resistance alleles are shared by two important meat breeds of Kazakhstan.

At the current stage of genetic studies of cattle, more and more attention is being drawn to autochthonous breeds. Native cattle have a number of prominent phenotypic traits and have preserved unique genes and their combinations lost by modern commercial breeds, which would be valuable to use in selective programs. We surveyed polymorphism of the Ukrainian autochthonous Gray breed according to alleles of exon 2 of the BoLA-DRB3 gene. The uniqueness of the gene lies in the broad variability of its allele variants. Significant informativeness at DNA level is quite important for genetic studies. We surveyed allele polymorphism using the PCR-RLFP method on DNA isolated from 88 samples of blood of cows and 5 samples of sperm. We identified 28 alleles, of which 23 variants were nomenclature ones and 5 (jba, *jab, *jbb, *nad and *nda) were “without established nomenclature”, their share accounting for 8.9%. Four alleles *06, *12, *16 and *jba had a frequency above 5% and occupied 69.9% of the breed’s allele fund overall. The commonest allele was BoLA-DRB3.2*16 (44.1%). In total, we found 40 genotypes. Considering the significant dominance of variant *16, as expected, 5 genotypes with its inclusion occurred: *16/*16, *12/*16, *06/*16, *16/*24 and *jba/*16. It was present in the genotype of two out three studied animals. Parameters of heterozygosity, effective number of alleles, Shannon and Pielou indices indicate that Ukrainian Gray cattle are characterized by lowest level of genetic variability and biodiversity according to the BoLA-DRB3 gene compared with other breeds. Due to significant dominance of allele *16, the breed has no inbred motifs. We noted deviation toward increase in homozygosity without deviations from the norm of the distribution according to Hardy-Weinberg equilibrium. The obtained results will be used for genetic-populational programs with the purpose of improving the genetic potential of cattle breeds in terms of economically beneficial traits and diseases of cattle.

Expression analysis of immune response genes in the mammary gland tissues of both healthy and infected animals help to explain the genetic basis of differential immune response. This study was conducted to analyze the differential expression of MHC class II DRB3 gene, in mastitis-affected and healthy animals of indicus (Sahiwal) and crossbred (Karan Fries) cattle. Real-time PCR was performed on the cDNA synthesized from the RNA isolated from PBMCs of the mastitis and healthy animals. However, no significant difference was observed in the expression of DRB3 in the two populations. The results point towards polymorphism supposed to be playing major role in differential immune response, rather than the expression of DRB3 gene as far as state of udder health is concerned.