Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA.
CBA and Faculty of Sciences and Technology, University of Azores, Rua Mãe de Deus no13, 9500-321, Ponta Delgada, Portugal.
Sci Rep. 2022 Aug 20;12(1):14237. doi: 10.1038/s41598-022-18722-7.
Steinernema carpocapsae is an entomopathogenic nematode (EPN) that rapidly infects and kills a wide range of insect hosts and has been linked to host immunosuppression during the initial stages of infection. The lethal nature of S. carpocapsae infections has previously been credited to its symbiotic bacteria; however, it has become evident that the nematodes are able to effectively kill their hosts independently through their excretion/secretion products (ESPs). Here we examined how the adult Drosophila melanogaster immune system is modulated in response to S. carpocapsae ESPs in an attempt to ascertain individual pathogenic contributions of the isolated compound. We found that the S. carpocapsae ESPs decrease the survival of D. melanogaster adult flies, they induce the expression of certain antimicrobial peptide-encoding genes, and they cause significant reduction in phenoloxidase enzyme activity and delay in the melanization response in males flies. We also report that S. carpocapsae ESPs affect hemocyte numbers in both male and female individuals. Our results indicate the manipulative role of EPN ESPs and reveal sex-specific differences in the host response against nematode infection factors. These findings are beneficial as they promote our understanding of the molecular basis of nematode pathogenicity and the parasite components that influence nematode-host interactions.
斯氏线虫是一种昆虫病原线虫（EPN），能快速感染和杀死广泛的昆虫宿主，并与感染初期的宿主免疫抑制有关。以前，斯氏线虫感染的致命性质归因于其共生细菌；然而，事实已经证明，线虫能够通过其排泄/分泌产物（ESP）有效地独立杀死其宿主。在这里，我们研究了成年黑腹果蝇的免疫系统如何对斯氏线虫的 ESP 做出反应，试图确定分离化合物的个体致病贡献。我们发现，斯氏线虫的 ESP 降低了黑腹果蝇成虫的存活率，诱导了某些抗菌肽编码基因的表达，并导致雄性果蝇酚氧化酶活性显著降低和黑化反应延迟。我们还报告说，斯氏线虫的 ESP 影响了雌雄个体的血细胞数量。我们的结果表明 EPN ESP 的操纵作用，并揭示了宿主对线虫感染因子反应的性别特异性差异。这些发现很有帮助，因为它们促进了我们对线虫致病性的分子基础和影响线虫-宿主相互作用的寄生虫成分的理解。
