Transmission success of the malaria parasite Plasmodium mexicanum into its vector:: role of gametocyte density and sex ratio
Transmission success of the malaria parasite Plasmodium mexicanum into its vector:: role of gametocyte density and sex ratio
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DOI：
10.1017/s0031182000006818
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发表时间：
2000-12-01
期刊：
影响因子：
2.4
通讯作者：
Schall, JJ
中科院分区：
文献类型：
--
作者：
Schall, JJ
疟原虫的生命周期依赖于寄生虫在进食血粉时从脊椎动物宿主传播到媒介中。传播成功可能在一定程度上取决于寄生虫在血液中的配子体密度和性别比例。墨西哥斑潜蝇是美国加利福尼亚州的一种栅栏蜥蜴寄生虫，它以沙蝇Lutzmyia vexator为媒介。在以自然感染的蜥蜴为献血者的实验传播中，传播成功率(以感染媒介的百分比和昆虫中肠上的寄生虫卵囊数量衡量)与配子体密度呈正相关，尽管密度高于20/1000的红细胞并不能改善传播。性别比(小配子体在感染中的比例)与配子体密度呈正相关。微配子体比例越高，传播率越高，但部分相关表明，这只是配子体密度较高的结果。这些结果与毒力和性别比理论一致，因为单克隆体感染应该产生更多以女性为主的性别比，并生长到最小的寄生虫血症，从而使克隆性传播最大化，而多克隆体感染将更接近1：1的性别比，当每个克隆体竞争传播到载体时，产生更高的寄生虫血症。
The life-cycle of Plasmodium depends on transmission of the parasite from the vertebrate host into its vector when the insect takes a bloodmeal. Transmission success may depend in part on the parasite's gametocyte density and sex ratio in the blood. P. mexicanum, a parasite of fence lizards in California, USA, exploits the sandfly Lutzomyia vexator as its vector. In experimental transmissions using naturally infected lizards as donors of blood, transmission success (measured as percentage of vectors infected and number of parasite oocysts on the insect's midgut) was positively related to gametocyte density, although density above 20/1000 erythrocytes did not improve transmission. Sex ratio (proportion of microgametocytes in the infection) was positively correlated with gametocyte density. Transmission improved with higher proportion of microgametocytes, but partial correlations revealed that this was a result only of higher gametocyte densities. These results agree with the theory of virulence and sex ratios because single clone infections should produce a more female-biased sex ratio and grow to the minimum parasitaemia that would maximize clonal transmission, whereas multiple clone infections will be closer to a 1 : 1 sex ratio and yield a higher parasitaemia when each clone competes for transmission to the vector.