DataSheet_1_Infection of C. elegans by Haptoglossa Species Reveals Shared Features in the Host Response to Oomycete Detection.xlsx

Oomycetes are a group of eukaryotic organisms that includes many important pathogens of animals and plants. Within this group, the Haptoglossa genus is characterised by the presence of specialised gun cells carrying a harpoon-like infection apparatus. While several Haptoglossa pathogens have been morphologically described, there are currently no host systems developed to study the infection process or host responses in the lab. In this study, we report that Haptoglossa species are potent natural pathogens of Caenorhabditis nematodes. Using electron microscopy, we characterise the infection process in C. elegans and demonstrate that the oomycete causes excessive tissue degradation upon entry in the body cavity, whilst leaving the host cuticle intact. We also report that the host transcriptional response to Haptoglossa infection shares similarities with the response against the oomycete Myzocytiopsis humicola, a key example of which is the induction of chitinase-like (chil) genes in the hypodermis. We demonstrate that this shared feature of the host response can be mounted by pathogen detection without any infection, as previously shown for M. humicola. These results highlight similarities in the nematode immune response to natural infection by phylogenetically distinct oomycetes.

卵菌（Oomycetes）是一类真核生物类群，包含诸多侵染动植物的重要病原菌。该类群中的Haptoglossa属（Haptoglossa）以拥有携带鱼叉状侵染装置的特化枪状细胞为典型特征。尽管已有多项研究对多种Haptoglossa病原菌开展了形态学描述，但目前尚未建立可用于实验室研究侵染过程与宿主应答的宿主实验体系。本研究证实，Haptoglossa物种为隐杆线虫属（Caenorhabditis）线虫的强效天然病原菌。借助电子显微镜（electron microscopy），本研究对秀丽隐杆线虫（C. elegans）的侵染过程进行了系统表征，并证实该卵菌侵入宿主体腔后会引发过度的组织降解，却能完整保留宿主角质层。本研究还发现，宿主针对Haptoglossa侵染的转录应答，与针对卵菌Myzocytiopsis humicola的转录应答存在相似性，其中一个关键特征是在皮下组织中诱导表达几丁质酶样（chitinase-like, chil）基因。正如此前针对M. humicola的研究结果所示，宿主可通过病原体识别而非实际侵染，触发这种共有的宿主应答特征。上述结果揭示了系统发育分化显著的卵菌侵染线虫时，宿主免疫应答所存在的相似性。