Mastitis is an inflammatory response of the mammary gland to irritation, injury, or infectious agents and is a major problem in the dairy industry. We genotyped bovine major histocompatibility complex (BoLA)-DRB3 and BoLA-DQA1 genes in 120 Holstein cattle with clinical mastitis and 85 randomly selected Holstein cattle in Japan by polymerase chain reaction-sequence-based typing. The mastitis cattle were divided into four groups according to the bacterial species that caused the mastitis (Staphylococcus aureus, Streptococci, Escherichia, and coagulase-negative staphylococci). The BoLA-DRB3 and BoLA-DQA1 heterozygosity of each group was compared with that of the control cattle, while the expected heterozygosities based on Hardy-Weinberg proportions and the observed heterozygosities for each locus were compared for each group. The Escherichia-induced and Streptococci-induced mastitis groups showed significant differences between their expected and observed heterozygosities with regard to their BoLA-DQA1 genes. No differences were observed for any group with regard to the BoLA-DRB3 genes. We then found that two BoLA-DQA1 alleles promoted susceptibility to Streptococci-induced mastitis, namely BoLA-DQA1*0101 and BoLA-DQA1*10012 and that the homozygous BoLA-DQA1*0101/0101 and BoLA-DQA1*10011/10011 genotypes promoted susceptibility to mastitis caused by Streptococci and Escherichia, respectively. This is the first report showing that heterozygosity of the BoLA-DQA1 gene is associated with resistance to mastitis progression.

Summary Recently, a 14‐bp insertion/deletion polymorphism (+14 bp/−14 bp) in exon 8 of the Human leucocyte antigen‐G (HLA‐G) gene has been studied extensively because this polymorphism has been associated with HLA‐G mRNA stability and could influence HLA‐G mRNA expression. We investigated the distribution of the 14‐bp insertion/deletion polymorphism in six different Chinese ethnic groups (Bulang, Wa, Hani, Jinuo, Maonan and Zhuang), which originated from three major ancient tribes (Di‐Qiang, Baipu and Baiyue) in China. Comparison of the 14‐bp insertion frequency in the six groups with other Chinese groups showed marked variation among the three ancient tribes, Di‐Qing (0.490–0.534), Baipu (0.470–0.609) and Baiyue (0.280–0.344). Furthermore, the frequencies of the 14‐bp insertion were similar in groups that came from the same ancient tribe, which indicated that the individuals who share the 14‐bp insertion have the most probably inherited the 14‐bp element from a common ancestor. In addition, an intra‐tribal comparison of the 14‐bp insertion/deletion frequencies between the descendants of the ancient ancestral tribes suggests that population histories or some environmental effects, such as founder effect or isolation, might also influence the distribution.

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