一個由美英等國科學(xué)家組成的國際研究小組近日測定了兩種致命瘧疾寄生蟲的基因組序列。這兩種瘧疾寄生蟲分別名為Plasmodium knowlesi和Plasmodium vivax,，其中P. knowlesi最近被認為是感染人類的一個主要瘧疾病原體,，而P. vivax則會致人極度虛弱,，甚至死亡。相關(guān)論文發(fā)表在10月9日的《自然》（Nature）雜志上,。
P. knowlesi的自然宿主是kra猴,，不過現(xiàn)在已經(jīng)確定它能夠感染人類。有證據(jù)表明，東南亞感染P. knowlesi的人普遍地被誤診為感染了相對更加溫和的P. malariae,，這導(dǎo)致了不恰當(dāng)?shù)闹委煼绞健?/p>
P. knowlesi是首個被遺傳測序的猴子瘧疾寄生蟲,，為與新近完成的P. vivax基因組和其它已測序的瘧原蟲基因組進行比較提供了新的研究機會。確定瘧疾寄生蟲之間的相似和不同有助于挑選遺傳標靶,，以進行疫苗和藥物的研發(fā)。
此次測序的另一個瘧疾寄生蟲是P. vivax,，它的致死率僅次于臭名昭著的P. falciparum,，75%的瘧疾感染及90%的瘧疾每年300萬致死數(shù)都是由后者導(dǎo)致的,。
P. vivax是非洲以外瘧疾的主要原因,，流行于亞洲和中,、南美洲潮濕的熱帶區(qū)域。P. vivax感染的瘧疾會導(dǎo)致多次復(fù)發(fā)的嚴重失能性疾病，有時會導(dǎo)致死亡,。
P. vivax能在涼爽季節(jié)以及P. falciparum不能耐受的更為溫和的氣候中傳播,，這使它能夠影響到世界上一半的人口,。此外，P. vivax對藥物的抗性也越來越普遍,，阻礙了對臨床案例的管理,。
與P. knowlesi一樣,，測定P. vivax的基因組序列將會產(chǎn)生對其獨特生物學(xué)特性的研究，而這同樣有助于確定新藥及疫苗開發(fā)的遺傳標靶,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature,，455, 799-803，A. Pain,，M. Berriman
The genome of the simian and human malaria parasite Plasmodium knowlesi
Plasmodium knowlesi is an intracellular malaria parasite whose natural vertebrate host is Macaca fascicularis (the 'kra' monkey); however, it is now increasingly recognized as a significant cause of human malaria, particularly in southeast Asia1, 2. Plasmodium knowlesi was the first malaria parasite species in which antigenic variation was demonstrated3, and it has a close phylogenetic relationship to Plasmodium vivax 4, the second most important species of human malaria parasite (reviewed in ref.4). Despite their relatedness, there are important phenotypic differences between them, such as host blood cell preference, absence of a dormant liver stage or 'hypnozoite' in P. knowlesi, and length of the asexual cycle (reviewed in ref. 4). Here we present an analysis of the P. knowlesi (H strain, Pk1(A+) clone5) nuclear genome sequence. This is the first monkey malaria parasite genome to be described, and it provides an opportunity for comparison with the recently completed P. vivax genome4 and other sequenced Plasmodium genomes6, 7, 8. In contrast to other Plasmodiumgenomes, putative variant antigen families are dispersed throughout the genome and are associated with intrachromosomal telomere repeats. One of these families, the KIRs9, contains sequences that collectively match over one-half of the host CD99 extracellular domain, which may represent an unusual form of molecular mimicry.
Nature,，455, 757-763，Jane M. Carlton,，Claire M. Fraser-Liggett
Comparative genomics of the neglected human malaria parasite Plasmodium vivax
The human malaria parasite Plasmodium vivax is responsible for 25–40% of the 515 million annual cases of malaria worldwide. Although seldom fatal, the parasite elicits severe and incapacitating clinical symptoms and often causes relapses months after a primary infection has cleared. Despite its importance as a major human pathogen, P. vivax is little studied because it cannot be propagated continuously in the laboratory except in non-human primates. We sequenced the genome of P. vivax to shed light on its distinctive biological features, and as a means to drive development of new drugs and vaccines. Here we describe the synteny and isochore structure of P. vivax chromosomes, and show that the parasite resembles other malaria parasites in gene content and metabolic potential, but possesses novel gene families and potential alternative invasion pathways not recognized previously. Completion of theP. vivax genome provides the scientific community with a valuable resource that can be used to advance investigation into this neglected species.
