Monoclonal antibody against the Plasmodium falciparum chitinase, PfCHT1, recognizes a malaria transmission-blocking epitope in Plasmodium gallinaceum ookinetes unrelated to the chitinase PgCHT1
Monoclonal antibody against the Plasmodium falciparum chitinase, PfCHT1, recognizes a malaria transmission-blocking epitope in Plasmodium gallinaceum ookinetes unrelated to the chitinase PgCHT1
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DOI：
10.1128/iai.70.3.1581-1590.2002
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发表时间：
2002-03-01
影响因子：
3.1
通讯作者：
Vinetz, JM
中科院分区：
文献类型：
--
作者：
Langer, RC;Li, FW;Vinetz, JM
为了启动蚊子中肠的入侵，疟原虫动卵细胞分泌几丁质酶，所述几丁质酶是穿过含有几丁质的围食基质以入侵上皮细胞表面所必需的。为了研究几丁质酶作为阻断疟原虫向蚊子传播的潜在免疫靶点，鉴定了一种单克隆抗体（MAb），其中和了迄今为止鉴定的恶性疟原虫PfCHT 1的唯一几丁质酶的酶活性。该单克隆抗体，命名为1C 3，以前显示与恶性疟原虫动卵细胞的顶端结构反应，也与鸡动卵细胞的离散顶端结构反应。在膜摄食实验中，单克隆抗体1C 3能显著抑制鸡胚肺孢子虫卵囊在蚊中肠的发育。单克隆抗体1C 3亲和分离了一个类似于210-kDa的抗原，在还原条件下，成为一个35-kDa的抗原。这种分离的35-kDa的蛋白质与抗血清产生交叉反应，所述抗血清针对源自鸡胚壳多糖酶活性位点的合成肽PgCHT 1，即使MAb 1C 3在Western印迹上不识别天然或重组PgCHT 1。因此，这种亲和纯化的35-kDa抗原似乎与先前鉴定的蛋白质PgCHT 2相似，PgCHT 2是鸡疫霉的推定的第二几丁质酶。表位作图表明，MAb 1C 3识别PfCHT 1的一个区域，该区域与伯氏曲霉、约氏毕赤酵母和鸡曲霉（PgCHT 1）的已测序几丁质酶中保守的同源氨基酸序列不同。衍生自映射表位的合成肽可用作亚单位传播阻断疫苗的组分。
To initiate invasion of the mosquito midgut, Plasmodium ookinetes secrete chitinases that are necessary to cross the chitin-containing peritrophic matrix en route to invading the epithelial cell surface. To investigate chitinases as potential immunological targets of blocking malaria parasite transmission to mosquitoes, a monoclonal antibody (MAb) was identified that neutralized the enzymatic activity of the sole chitinase of Plasmodium falciparum, PfCHT1, identified to date. This MAb, designated 1C3, previously shown to react with an apical structure of P. falciparum ookinetes, also reacts with a discrete apical structure of A gallinaceum ookinetes. In membrane feeding assays, MAb 1C3 markedly inhibited P. gallinaceum oocyst development in mosquito midguts. MAb 1C3 affinity isolated an similar to210-kDa antigen which, under reducing conditions, became a 35-kDa antigen. This isolated 35-kDa protein cross-reacted with an antiserum raised against a synthetic peptide derived from the A gallinaceum chitinase active site, PgCHT1, even though MAb 1C3 did not recognize native or recombinant PgCHT1 on Western blot. Therefore, this affinity-purified 35-kDa antigen appears similar to a previously identified protein, PgCHT2, a putative second chitinase of P. gallinaceum. Epitope mapping indicated MAb 1C3 recognized a region of PfCHT1 that diverges from a homologous amino acid sequence conserved within sequenced chitinases of A berghei, P. yoelii, and A gallinaceum (PgCHT1). A synthetic peptide derived from the mapped 10 epitope may be useful as a component of a subunit transmission-blocking vaccine.