布氏田鼠和青海田鼠自然种群鼠疫抗性差异

Divergence of Plague Resistance between Lasiopodomys brandtii and Lasiopodomys fuseus in Natural Populations

目的以MHC class Ⅱ gene β基因为分子标记研究布氏田鼠和青海田鼠自然种群鼠疫抗性差异的遗传基础。方法对布氏田鼠和青海田鼠进行鼠疫菌攻毒试验,并对死亡和存活的两种田鼠MHC class Ⅱ gene β基因酶切后的等位基因频率和基因型频率进行比较分析。结果布氏田鼠种群鼠疫抗性个体Rsa Ⅰ E和Rsa Ⅰ F等位基因较高的频率具有重要统计学意义(抗性个体:0.3095、0.2738;易感个体:0.0571、0.0286);青海田鼠种群鼠疫抗性个体Rsa Ⅰ F等位基因较高的频率具有重要统计学意义(抗性个体:0.3704;易感个体:0.0682)。对布氏田鼠和青海田鼠MHC class Ⅱ gene β基因纯合型序列分析显示,青海田鼠和布氏田鼠MHC class Ⅱ gene β基因有68个多态(变异)位点,占26.1%;其中布氏田鼠39个,青海田鼠27个,二者存在12碱基的差异。序列分析显示,布氏田鼠MHC class Ⅱ gene β基因在第27、53、63、70、91、126、127、128、129、160、213、214、215位碱基上存在多态性;而青海田鼠在第27、53、63、126、127、128、129、160、213、214、215位碱基上存在多态性。Rsa Ⅰ酶切揭示,青海田鼠的MHCclass Ⅱ gene β基因缺少等位基因E,多态性低于布氏田鼠,这可能是两自然种群鼠疫抗性差异的分子机制。结论 MHC class Ⅱ gene β基因多态性可能与布氏田鼠和青海田鼠鼠疫抗性存在相关性;MHC class Ⅱ gene β基因和其他未确定的鼠疫抗性标记可为研究宿主进化和疾病动力学提供有用的生物学信息。

Objective MHC class Ⅱ gene β was used as candidate gene to investigate the genetic basis of plague resistance in natural populations of Lasiopodomys brandtii and L.fuseus experimentally infected with virulent Y.pestis.Methods We compared allelic frequencies and genotypes frequencies of RFLPs-RsaⅠMHC class Ⅱ gene β of dying and viable plague challenged L.brandtii and L.fuseus.Rusults Our results suggested that allele RsaⅠE and RsaⅠF were associated with resistance to plague in L.brandtii（resistant individuals：0.3095,0.2738;susceptible individuals：0.0571,0.0286;P0.01）;allele RsaⅠF was associated with resistance to plague in L.fuseus（resistant individuals：0.3704;susceptible individuals：0.0682;P0.01）.Sequence analysis showed that 68 bases mutations were found,39 bases mutations in L.brandtii and 27 bases mutations in L.fuseus.Statistical results showed that polymorphism sites at positions 27,53,63,70,91,126,127,128,129,160,213,214,215 in L.brandtii and 27,53,63,126,127,128,129,160,213,214,215 in L.fuseus.RsaⅠE alleles were not discovered in L.fuseus by comparing with sequences of MHC class Ⅱ gene β of L.brandtii.This may reveal the molecular mechanisms for divergence of plague resistance between L.brandtii and L.fuseus in natural populations.Conclusion The polymorphism of MHC class Ⅱ gene β may involved in L.brandtii and L.fuseus plague resistance.MHC class Ⅱ gene β and other undetermined plague resistance markers would provide useful biological information about host evolution and disease dynamics.