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以自行设计合成的一对引物（＃Ｐ５／＃７３１），应用聚合酶链反应技术（ＰＣＲ），从基因组ＤＮＡ中扩增了编码９０ＫＤａ的变异性表面特异蛋白的几乎全长的基因。ＰＣＲ产物被克隆到质粒中，并通过双脱氧链终止法将插入的基因片段进行了序列分析，推导出的氨基酸序列半胱氨酸含量为１１．８ｍｏｌ％，而且多数的半胱氨酸是以ＣＸＸＣ基序重复出现２６次，序列分析发现有２个天冬酰胺连接的糖基位点。基因序列显示出一个２０１９ｂｐ长的开放阅读框架。同源性比较发现它与编码７２ＫＤａ人的兰氏贾第鞭毛虫虫株的变异性表面蛋白基因，有相当强的同源性
A pair of primers (# P5 / # 731) designed by the authors was designed and an almost full-length gene encoding a 90 kDa variant surface-specific protein was amplified from genomic DNA using polymerase chain reaction (PCR). The PCR product was cloned into a plasmid and the inserted gene fragment was sequenced by the dideoxy chain termination method. The deduced amino acid sequence had a cysteine content of 11.8 mol%, and most of the cysteines were The CXXC motif was repeated 26 times and sequence analysis revealed two asparagine linked glycosyl sites. The gene sequence shows a 2019bp long open reading frame. Homology comparison showed that it had a rather strong homology with the mutant surface protein gene coding for the 72 kDa human Giardia lamblia strain