Major histocompatibility complex (MHC) is an important complex that presents antigen to T cells. The second exon of swine MHC (SLA) class II genes has antigen binding sites that bind with extracellular antigen. Populations with high MHC gene diversity result in low gut microbiota, and individuals with MHC gene heterozygote have lower gut microbiota diversity than that of homozygote. The pig is an animal with organs physiologically and anatomically similar to humans than any other mammal, and the pig is also suitably developed as a laboratory animal to establish the animal models of human disease. However, the relationship between SLA genetic diversity and the gut microbes of the pig is ambiguous. We studied the characterization of SLA class II genes and calculated the genetic diversity, and then we selected experimental animal groups divided by different SLA genotypes to investigate the gut microbiota composition by sequencing V3 to V4 hypervariable regions of bacterial 16 s rRNA from fecal samples. Our results showed that Guizhou minipigs had a low SLA genetic diversity, which may be due to the small founder population. The Guizhou minipig population deviated from neutral selection and balancing selection, which shows that Guizhou minipigs experience a strong artificial selection in recent years. We observed that the sex differences influenced gut microbiota much more deeply than that of genetics. Our results also showed that the individual with heterozygote of genes at the SLA class II region had much higher abundant gut microbiota than that of the homozygote.

主要组织相容性复合物 (MHC) 是一种重要的复合物，可将抗原呈递给 T 细胞。猪 MHC (SLA) II 类基因的第二个外显子具有与细胞外抗原结合的抗原结合位点。具有高 MHC 基因多样性的群体导致肠道微生物群低，而具有 MHC 基因杂合子的个体的肠道微生物群多样性低于纯合子。猪是一种器官在生理和解剖上与人类相似的动物，而不是任何其他哺乳动物，猪也适合作为实验室动物来建立人类疾病的动物模型。然而，SLA遗传多样性与猪肠道微生物之间的关系并不明确。我们研究了SLA II类基因的特征并计算了遗传多样性，然后我们选择了按不同 SLA 基因型划分的实验动物组，通过对粪便样本中细菌 16 s rRNA 的 V3 至 V4 高变区进行测序来研究肠道微生物群组成。我们的研究结果表明，贵州小型猪的 SLA 遗传多样性较低，这可能是由于始祖种群较小。贵州小型猪种群偏离了中性选择和平衡选择，说明贵州小型猪近年来经历了强烈的人工选择。我们观察到，性别差异对肠道微生物群的影响比遗传影响更深。我们的结果还表明，在 SLA II 类区域具有基因杂合子的个体的肠道微生物群比纯合子高得多。