Tsuboi T, Kaslow D C, Gozar M M, Tachibana M, Cao Y M, Torii M
Department of Parasitology, Ehime University School of Medicine, Shigenobu, Ehime, Japan.
Mol Med. 1998 Dec;4(12):772-82.
For many malarious regions outside of Africa, development of effective transmission-blocking vaccines will require coverage against both Plasmodium falciparum and P. vivax. Work on P. vivax transmission-blocking vaccines has been hampered by the inability to clone the vaccine candidate genes from this parasite.
To search for genes encoding the ookinete surface proteins from P. vivax, the DNA sequences of the eight known proteins in the P25 subfamily (Pfs25, Pgs25, Pys25, Pbs25) and in the P21/28 subfamily (Pfs28, Pgs28, Pys21, Pbs21) of zygote/ookinete surface proteins were aligned. Regions of highest identity were used to design degenerate PCR oligonucleotides. Genomic DNA from the Sal I strain of P. vivax and genomic and splinkerette DNA libraries were used as PCR templates. To characterize the polymorphisms of Pvs25 and Pvs28, these two genes were PCR amplified and the DNA sequences were determined from genomic DNA extracted from patients infected with P. vivax.
Analysis of the deduced amino acid sequence of Pvs28 revealed a secretory signal sequence, four epidermal growth factor (EGF)-like domains, six copies of the heptad amino acid repeat (GSGGE/D), and a short hydrophobic region. Because the fourth EGF-like domain has four rather than six cysteines, the gene designated Pvs28 is the presumed homologue of P21/28 subfamily members. Analysis of the deduced amino acid sequence of Pvs25 revealed a similar structure to that of Pvs28. The presence of six rather than four cysteines in the fourth EGF-like domain suggested that Pvs25 is the homologue of P25 subfamily members. Several regions of genetic polymorphisms in Pvs25 and Pvs28 were identified in field isolates of P. vivax.
The genes encoding two ookinete surface proteins, Pvs28 and Pvs25, from P. vivax have been isolated and sequenced. Comparison of the primary structures of Pvs25, Pvs28, Pfs25, and Pfs28 suggest that there are regions of genetic polymorphism in the P25 and P21/28 subfamilies.
对于非洲以外的许多疟疾流行地区，开发有效的传播阻断疫苗需要同时覆盖恶性疟原虫和间日疟原虫。间日疟原虫传播阻断疫苗的研究因无法从该寄生虫中克隆候选疫苗基因而受到阻碍。
为了寻找间日疟原虫动合子表面蛋白的编码基因，对合子/动合子表面蛋白P25亚家族（Pfs25、Pgs25、Pys25、Pbs25）和P21/28亚家族（Pfs28、Pgs28、Pys21、Pbs21）中8种已知蛋白的DNA序列进行比对。用同源性最高的区域设计简并PCR寡核苷酸。间日疟原虫Sal I株的基因组DNA以及基因组和连接子文库用作PCR模板。为了表征Pvs25和Pvs28的多态性，对这两个基因进行PCR扩增，并从感染间日疟原虫患者提取的基因组DNA中测定DNA序列。
对Pvs28推导的氨基酸序列分析显示有一个分泌信号序列、四个表皮生长因子（EGF）样结构域、六个七肽氨基酸重复序列（GSGGE/D）拷贝以及一个短的疏水区。由于第四个EGF样结构域有四个而非六个半胱氨酸，所以命名为Pvs28的基因被认为是P21/28亚家族成员的同源物。对Pvs25推导的氨基酸序列分析显示其结构与Pvs28相似。第四个EGF样结构域中有六个而非四个半胱氨酸，这表明Pvs25是P25亚家族成员的同源物。在间日疟原虫的野外分离株中鉴定出Pvs25和Pvs28的几个基因多态性区域。
已分离并测序了间日疟原虫编码两种动合子表面蛋白Pvs28和Pvs25的基因。Pvs25、Pvs28、Pfs25和Pfs28一级结构的比较表明，P25和P21/28亚家族存在基因多态性区域。
