Evaluation of Polymorphism of the Immune System Genes TNF and TLR2 in Cattle

In this article the results of genotyping of tumor necrosis factor (TNF) and Toll-like receptor 2 (TLR2) genes among 644 head of cattle of six breeds belonging to four different genetic roots are presented. The Kholmogory and Holstein breeds of black-and-white root, the Ayrshire breed of red root, the Kostroma and Brown Swiss breed of brown root, and the fawn Simmental breed were studied. The PCR-RFLP method was used to identify alleles and genotypes. Significant differences in allele frequency of the TNF and TLR2 genes were observed between breeds of different genetic roots (p < 0.001) and between breeds of dairy and dairy-meat productivity (p < 0.001). In five of the six cattle breeds studied, the predominance of the TLR2T allele was revealed. The highest frequency of the TLR2T allele (0.99) was found in the Ayrshire breed. The herd of Ayrshire cows is close to being monomorphic for the TLR2 gene; 98% of the animals have the homozygous TLR2TT genotype. A more uniform distribution of alleles and genotypes for the TLR2 gene was found in black-and-white animals: in Holstein cattle, the average frequency of the TLR2T allele was 0.78; in Kholmogory cattle, it was 0.83. The TLR2TT genotype was detected in the majority of Holstein (61%) and Kholmogory (69%) cows. The frequency of the TLR2T allele in the Simmental breed was 0.62; in the Kostroma breed, it was 0.67. In Simmental and Kostroma cows, the heterozygous TLR2TG genotype is more common (54 and 47% respectively). A different picture of the distribution of allele and genotype frequencies was revealed in Brown Swiss animals. The TLR2T allele frequency averages 0.26. More than half of Brown Swiss cows (55%) are homozygous for TLR2GG. In all breeds, the TNFB allele predominated with a frequency of occurrence ranging from 0.61 in Holstein cattle to 0.98 in the Brown Swiss breed. A high frequency of the TNFB allele was found in the Kostroma (0.94), Ayrshire (0.885), and Simmental (0.80) breeds. In the Kholmogory breed, the average frequency of the TNFB allele was 0.72. The highest frequency of the TNFBB genotype was found in Brown Swiss herds (96%). The predominance of the homozygous TNFBB genotype was revealed in Kholmogory (53%), Simmental (62%), Ayrshire (77%), and Kostroma cattle (87.5%). In Holstein cows, the majority of animals (53%) carry the heterozygous TNFАВ genotype. In three breeds, Ayrshire, Kostroma, and Brown Swiss, the TNFAA genotype was not detected.