Institute of Insect Science, Zhejiang University, Hangzhou, China.
Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects, and Zhejiang Provincial Key Lab of Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, China.
Virulence. 2023 Dec;14(1):2171691. doi: 10.1080/21505594.2023.2171691.
Polydnaviruses (PDVs), obligatory symbionts with parasitoid wasps, function as host immune suppressors and growth and development regulator. PDVs can induce host haemocyte apoptosis, but the underlying mechanism remains largely unknown. Here, we provided evidence that, during the early stages of parasitism, the activated bracovirus (CvBV) reduced the overall number of host haemocytes by inducing apoptosis. We found that one haemocyte-highly expressed CvBV gene, , could induce haemocyte apoptosis. Further analyses showed that has four homologs from other bracoviruses and BV from wasps in the genus , and all four of them possessed a similar structure containing 3 copies of a well-conserved motif (Gly-Tyr-Pro-Tyr, GYPY). Mass spectrometry analysis revealed that CvBV-26-4 was secreted into plasma by haemocytes and then degraded into peptides that induced the apoptosis of haemocytes. Moreover, ectopic expression of caused fly haemocyte apoptosis and increased the susceptibility of flies to bacteria. Based on this research, a new family of bracovirus genes, Bracovirus apoptosis-inducing proteins (), was proposed. Furthermore, it was discovered that the development of wasp larvae was affected when the function of CvBV BAP was obstructed in the parasitized hosts. The results of our study indicate that the gene family from the bracoviruses group is crucial for immunosuppression during the early stages of parasitism.
多粒包埋病毒（PDVs）是寄生蜂的必需共生体，具有宿主免疫抑制和生长发育调控作用。PDVs 可以诱导宿主血细胞凋亡，但具体的作用机制尚不清楚。在这里，我们提供了证据表明，在寄生的早期阶段，激活的 bracovirus（CvBV）通过诱导细胞凋亡来减少宿主血细胞的总数。我们发现一个血细胞高表达的 CvBV 基因 ，可以诱导血细胞凋亡。进一步的分析表明， 有四个来自其他 bracoviruses 的同源物和 属中的黄蜂 BV，它们都具有相似的结构，包含 3 个保守基序（Gly-Tyr-Pro-Tyr，GYPY）的拷贝。质谱分析显示，CvBV-26-4 由血细胞分泌到血浆中，然后降解成诱导血细胞凋亡的肽。此外，异位表达 导致果蝇血细胞凋亡，并增加了果蝇对细菌的易感性。基于这项研究，提出了一个新的 bracovirus 基因家族，Bracovirus apoptosis-inducing proteins（BAPs）。此外，还发现当寄生宿主中 CvBV BAP 的功能受阻时，黄蜂幼虫的发育受到影响。我们的研究结果表明，bracoviruses 组的 基因家族在寄生早期的免疫抑制中至关重要。
