AGE-DEPENDENT CARRIAGE OF MULTIPLE PLASMODIUM-FALCIPARUM MEROZOITE SURFACE ANTIGEN-2 ALLELES IN ASYMPTOMATIC MALARIA INFECTIONS
AGE-DEPENDENT CARRIAGE OF MULTIPLE PLASMODIUM-FALCIPARUM MEROZOITE SURFACE ANTIGEN-2 ALLELES IN ASYMPTOMATIC MALARIA INFECTIONS
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DOI：
10.4269/ajtmh.1995.52.81
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发表时间：
1995-01-01
影响因子：
3.3
通讯作者：
MERCEREAUPUIJALON, O
中科院分区：
文献类型：
--
作者：
NTOUMI, F;CONTAMIN, H;MERCEREAUPUIJALON, O
在塞内加尔的一个疟疾完全流行的村庄，对人疟原虫恶性疟原虫裂殖子表面抗原-2基因的遗传多样性进行了分析。在1992年的高传输季节进行了横断面调查的65名居民。通过显微镜检查（77%阳性样本）和使用单一（29%或38%阳性样本，取决于使用的引物）或巢式聚合酶链反应（PCR）（78%阳性样本）的DNA扩增检测恶性疟原虫。阳性巢式PCR和显微镜检查之间的重叠不完全。在琼脂糖凝胶上分析PCR片段的大小多态性，随后通过与家族特异性探针杂交将其分配到主要等位基因家族3D 7或FC 27。发现两个等位基因家族，FC 27的患病率略高。还观察到在严格条件下不能与参考探针杂交的嵌合等位基因。一些分型使用一种新的PCR方法，使用杂交引物对，由一个家庭特异性的正义寡核苷酸与一个反义寡核苷酸特定的其他家庭。结合分型技术，82%的阳性PCR结果产生一个以上的条带。在15岁左右，每个携带者的片段总数和等位基因类型的数量都明显减少。DNA片段的数量从15岁之前每个携带者平均4个突然下降到15岁以上的平均2个。同样，携带一种以上等位基因类型的个体数量随着年龄的增长而减少，截止年龄为15岁。这与观察到的该村庄的流行率和寄生虫密度下降相平行。然而，没有任何特定等位基因的年龄依赖性携带，在所有年龄组中都检测到了各种等位基因。因此，结果表明，获得抗寄生虫免疫不仅会导致寄生虫负荷减少，而且会降低感染的复杂性。
Genetic diversity of the merozoite surface antigen-2 gene of the human malaria parasite Plasmodium falciparum has been analyzed in a Senegalese village where malaria is holoendemic. A cross-sectional survey of 65 residents was performed in 1992 during the high transmission season. Plasmodium falciparum was detected both by microscopy (77% positive samples) and DNA amplification using a single (29% or 38% positive samples, depending on the primers used) or nested polymerase chain reaction (PCR) (78% positive samples). The overlap between the positive nested PCR and microscopic examination was not complete. The PCR fragments were analyzed for size polymorphism on agarose gels, and were subsequently assigned to the major allelic families 3D7 or FC27 by hybridization with family-specific probes. Both allelic families were found, with a slightly higher prevalence for FC27. Chimeric alleles that failed to hybridize under stringent conditions to the reference probes were also observed. Some were typed using a novel PCR approach, using hybrid pairs of primers, consisting of a family-specific sense oligonucleotide combined with an antisense oligonucleotide specific for the other family. Combining typing techniques, 82% of the positive PCR results yielded more than one band. Both the overall number of fragments and the number of allelic types per carrier were markedly reduced around the age of 15 years. The number of DNA fragments decreased abruptly from an average of four per carrier before the age of 15 years to an average of two in individuals more than 15 years of age. Similarly, the number of individuals carrying more than one allelic type decreased with age, with a cutoff at the age of 15 years. This parallels the observed decrease in prevalence and parasite density in this village. There was, however, no age-dependent carriage of any particular allele, with the various alleles being detected in all age groups. The results, therefore, indicate that acquiring anti-parasite immunity not only results in decreasing parasite load, but also in decreasing the complexity of the infections.