Amills M, Ramiya V, Norimine J, Lewin H A
Department of Animal Sciences, University of Illinois at Urbana-Champaign 61801, USA.
Rev Sci Tech. 1998 Apr;17(1):108-20. doi: 10.20506/rst.17.1.1092.
Studies of the major histocompatibility complex (MHC) of cattle over the past twenty years have revealed a reasonably detailed picture of the genetic organisation and function of the genes within this genetic system. Serological and biochemical analysis of lymphocyte cell surface antigens provided the first evidence for highly polymorphic MHC genes in cattle and other ruminant species. The MHC of cattle was thus named the bovine leucocyte antigen (BoLA) system. During the past 10 years, tools of molecular biology have been used to characterise the number of MHC genes, their sequence and fine structure in a number of ruminant species. Although individual MHC genes were found to have clear orthologues among ruminants and other mammalian species, the MHC of cattle, and probably that of sheep and goats, has a unique genetic organisation. Cattle have a class II gene cluster (class IIb region) which is physically distant from all the other MHC genes on the same chromosome. Moreover, genes involved in antigen processing, such as the proteosome subunit locus LMP2, are also found in the class IIb region, demonstrating that these genes need not be in close proximity to other MHC genes to function normally. The MHC class I and class II gene products of ruminants present processed peptides to T lymphocytes which mediate helper and cytotoxic functions. Identification of peptide binding motifs of cattle MHC class I molecules indicates that ruminant MHC molecules function in a similar manner to those of mice and humans. These functional studies provide a firm molecular basis for a number of well-documented associations with infectious diseases, although a detailed understanding of the immunogenetic mechanisms underlying these associations has yet to be elucidated.
在过去二十年中，对牛的主要组织相容性复合体（MHC）的研究揭示了该遗传系统内基因的遗传组织和功能的相当详细的情况。对淋巴细胞表面抗原的血清学和生化分析为牛和其他反刍动物物种中高度多态的MHC基因提供了首个证据。因此，牛的MHC被命名为牛白细胞抗原（BoLA）系统。在过去十年中，分子生物学工具已被用于表征许多反刍动物物种中MHC基因的数量、序列和精细结构。尽管发现单个MHC基因在反刍动物和其他哺乳动物物种中有明确的直系同源物，但牛的MHC，可能还有绵羊和山羊的MHC，具有独特的遗传组织。牛有一个II类基因簇（IIb类区域），它在物理上与同一条染色体上的所有其他MHC基因相距甚远。此外，参与抗原加工的基因，如蛋白酶体亚基基因座LMP2，也在IIb类区域中被发现，这表明这些基因在功能正常时不一定与其他MHC基因紧密相邻。反刍动物的MHC I类和II类基因产物将加工后的肽呈递给介导辅助和细胞毒性功能的T淋巴细胞。牛MHC I类分子的肽结合基序的鉴定表明，反刍动物的MHC分子的功能与小鼠和人类的相似。这些功能研究为一些与传染病有充分记录的关联提供了坚实的分子基础，尽管对这些关联背后的免疫遗传机制的详细理解还有待阐明。
