Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany.
BMC Evol Biol. 2019 Jan 10;19(1):14. doi: 10.1186/s12862-019-1352-0.
The highly polymorphic genes of the major histocompatibility complex (MHC) class I are involved in defense against viruses and other intracellular pathogens. Although several studies found reduced MHC class I diversity in bonobos in comparison to the closely related chimpanzee, it is unclear if this lower diversity also influences the functional ability of MHC class I molecules in bonobos. Here, we use a bioinformatic approach to analyze the viral peptide binding ability of all published bonobo MHC class I molecules (n = 58) in comparison to all published chimpanzee MHC class I molecules (n = 161) for the class I loci A, B, C and A-like.
We examined the peptide binding ability of all 219 different MHC class I molecules to 5,788,712 peptides derived from 1432 different primate viruses and analyzed the percentage of bound peptides and the overlap of the peptide binding repertoires of the two species. We conducted multiple levels of analysis on the "species"-, "population"- and "individual"-level to account for the characterization of MHC variation in a larger number of chimpanzees and their broader geographic distribution. We found a lower percentage of bound peptides in bonobos at the B locus in the "population"-level comparison and at the B and C loci in the "individual"-level comparison. Furthermore, we found evidence of a limited peptide binding repertoire in bonobos by tree-based visualization of functional clustering of MHC molecules, as well as an analysis of peptides bound by both species.
Our results suggest a reduced MHC class I viral peptide binding ability at the B and C loci in bonobos compared to chimpanzees. The effects of this finding on the immune defense against viruses in wild living bonobos are unclear. However, special caution is needed to prevent introduction and spread of new viruses to bonobos, as their defensive ability to cope with new viruses could be limited compared to chimpanzees.
主要组织相容性复合体（MHC）I 类的高度多态性基因参与了针对病毒和其他细胞内病原体的防御。尽管有几项研究发现，与密切相关的黑猩猩相比，倭黑猩猩的 MHC I 类多样性较低，但目前尚不清楚这种较低的多样性是否也会影响 MHC I 类分子在倭黑猩猩中的功能能力。在这里，我们使用生物信息学方法分析了已发表的所有 58 个倭黑猩猩 MHC I 类分子（n=58）与已发表的所有 161 个黑猩猩 MHC I 类分子（n=161）针对 I 类基因座 A、B、C 和 A 样的病毒肽结合能力。
我们检测了 219 种不同的 MHC I 类分子对来自 1432 种不同灵长类病毒的 5788712 种肽的结合能力，并分析了两种物种的结合肽的百分比和结合谱的重叠。我们在“物种”、“种群”和“个体”水平上进行了多层次的分析，以解释在更多的黑猩猩和更广泛的地理分布中 MHC 变异的特征。我们发现，在“种群”水平比较中，B 基因座上的结合肽百分比较低，在“个体”水平比较中，B 和 C 基因座上的结合肽百分比较低。此外，我们通过基于树的功能聚类对 MHC 分子进行可视化，以及对两种物种结合的肽进行分析，发现了倭黑猩猩的肽结合谱有限的证据。
与黑猩猩相比，我们的研究结果表明，倭黑猩猩的 MHC I 类病毒肽结合能力在 B 和 C 基因座上降低。这种发现对野生倭黑猩猩抵抗病毒的免疫防御的影响尚不清楚。然而，由于与黑猩猩相比，它们应对新病毒的防御能力可能有限，因此在向倭黑猩猩引入和传播新病毒时需要特别小心。
