非洲输入性恶性疟病例裂殖子表面蛋白1等位基因型检测

Analysis of MSP1 Allelotypes in Imported Cases of Plasmodium falciparum Malaria from Africa

目的了解输入性恶性疟原虫裂殖子表面蛋白1(MSP1)等位基因型特征。方法采集非洲疟疾流行区回国人员中恶性疟现症患者血样,采用巢式PCR方法,用恶性疟原虫MSP1基因特异引物扩增疟原虫虫株MSP1基因第2区与第3区部分片段,并对MSP1等位基因型进行分析。结果 135例输入性恶性疟患者中检出MSP1等位基因117例,检出率为86.7%。117例扩增阳性的患者中,MAD20、K1、RO33、MAD20+K1、MAD20+RO33、K1+RO33和MAD20+K1+RO33型的检出率分别为6.0%(7/117)、36.8%(43/117)、20.5%(24/117)、6.8%(8/117)、3.4%(4/117)、17.1%(20/117)和9.4%(11/117),其中混合型感染占36.8%(43/135),MSP1等位基因多重感染平均数(MOI)为1.46。MAD20型、K1型和RO33型恶性疟患者中重症患者比例差异无统计学意义(P>0.05);74例单一型和43例混合型感染者中重症患者比例分别为25.7%(19/74)和32.6%(14/43),2种感染者回国前在国外停留的平均天数分别为(241±176)d和(285±216)d,两者间差异均无统计学意义(P>0.05)。结论非洲输入性恶性疟患者感染的疟原虫MSP1基因的3种基因型和4种混合型均存在,以K1型和RO33型为优势基因型。

Objective To understand the allelotype characteristics of the merozoite surface protein 1（MSP1） in imported Plasmodium falciparum. Methods Blood samples were collected from P. falciparum-infected patients returning from African malaria endemic areas. Nested PCR was used to amplify gene fragments of MSP1 coding for block 2 and block 3 motifs of MSP1 of P. falciparum by using the MSP1-specific primers. Then the allelotype of MSP1 was analyzed. Results The MSP1 allelotype was detected in 117 of 135 blood samples, with a detection rate of 86.7%. In the 117 cases with successful PCR amplification, the detection rates for MAD20, K1, RO33, MAD20＋K1, MAD20＋RO33, K1＋RO33 and MAD20＋K1＋RO33 were 6.0%（7/117）, 36.8%（43/117）, 20.5%（24/117）, 6.8%（8/117）, 3.4%（4/117）, 17.1%（20/117） and 9.4%（11/117）, respectively, wherein the mixed infection accounted for 36.8%（43/135）. The mean multiplicity of infection（MOI） of MSP1 allelotype was 1.46. There was no significant difference in the proportion of patients with major severity of illness among the MAD20, K1 and RO33 genotypes. The proportions of patients with major severity of illness were 25.7%（19/74） and 32.6%（14/43） in 74 cases of singular infection and 43 cases of mixed infection, respectively. The two infection types of patients had 241±176 days and 285±216 days of stay abroad, with no significant difference between them. Conclusion The three genotypes of MSP1 and their four types of combination exist in imported cases of P. falciparum malaria from Africa. K1 and RO33 are the dominant genotypes.