The dynamic transcriptome of Plasmodium malariae in the mosquito

To survive and multiply in different host niches, malaria parasites require sets of proteins that are expressed during the life cycle in a timely manner. Plasmodium malariae is a human malaria parasite that is present in most malaria-endemic regions. However, this species remains enigmatic because it is very challenging to culture, its low parasitaemia in human infections, and frequent co-infection with other malarias . We investigate the transcriptome of P. malariae during transmission in the vector by analyzing RNA-seq data from midgut and salivary gland parasite stages obtained in two experimental mosquito infections with field P. malariae isolates. Our analysis results in 3,699 expressed genes, of which 263 are developmentally regulated and 1,338 are P. malariae-specific, including genes with unknown functions and without orthologs in other Plasmodium. We detected unique expression patterns of the ApiAP2 family of transcription factors, many of which appear to function as master regulators during sporogony. We found expressed several members of multigene families, like PIR, PHIST, fam-l, and described new families potentially showing transcriptional heterogeneity. Our findings point to the uniqueness of the P. malariae transcriptome, probably related to different transmission traits in the vector, and the lower pathogenicity and virulence in the human. Transcriptome profiling (RNA-seq) of mosquito tissues after experimental infections with P. malariae

为在不同宿主生态位中存活并增殖，疟原虫需要一套在生命周期内时序性表达的蛋白质集合。三日疟原虫（Plasmodium malariae）是一种人类疟原虫，广泛分布于多数疟疾流行区域。但该物种至今仍颇具神秘性：其体外培养难度极高，人体感染后的虫血症（parasitaemia）水平较低，且常与其他疟原虫发生混合感染。

本研究针对媒介传播阶段的三日疟原虫转录组展开探究，通过分析两份基于野外分离的三日疟原虫毒株、经实验感染蚊虫后获取的中肠与唾液腺寄生虫阶段样本的RNA-seq数据完成相关分析。本研究共鉴定出3699个表达基因，其中263个具备发育调控特性，1338个为三日疟原虫特异性基因——涵盖功能未知且在其他疟原虫中无同源基因（orthologs）的基因。

我们检测到ApiAP2家族转录因子（ApiAP2 family of transcription factors）的独特表达模式，其中多数似乎在孢子生殖过程中充当主调控因子。本研究发现PIR、PHIST、fam-l等多基因家族的多个成员存在表达现象，并描述了可能表现出转录异质性的新型基因家族。

本研究结果揭示了三日疟原虫转录组的独特性，这或与其在媒介昆虫中的差异化传播特性以及人类宿主中较低的致病性与毒力相关。
实验感染三日疟原虫后的蚊虫组织转录组分析（RNA-seq）