University of California, Davis, Davis, CA.
Vet Pathol. 2023 Sep;60(5):689-703. doi: 10.1177/03009858231180488. Epub 2023 Jun 21.
Mealworms are one of the most economically important insects in large-scale production for human and animal nutrition. Densoviruses are highly pathogenic for invertebrates and exhibit an extraordinary level of diversity which rivals that of their hosts. Molecular, clinical, histological, and electron microscopic characterization of novel densovirus infections is of utmost economic and ecological importance. Here, we describe an outbreak of densovirus with high mortality in a commercial mealworm () farm. Clinical signs included inability to prehend food, asymmetric locomotion evolving to nonambulation, dehydration, dark discoloration, and death. Upon gross examination, infected mealworms displayed underdevelopment, dark discoloration, larvae body curvature, and organ/tissue softness. Histologically, there was massive epithelial cell death, and cytomegaly and karyomegaly with intranuclear inclusion (InI) bodies in the epidermis, pharynx, esophagus, rectum, tracheae, and tracheoles. Ultrastructurally, these InIs represented a densovirus replication and assembly complex composed of virus particles ranging from 23.79 to 26.99 nm in diameter, as detected on transmission electron microscopy. Whole-genome sequencing identified a 5579-nucleotide-long densovirus containing 5 open reading frames. A phylogenetic analysis of the mealworm densovirus showed it to be closely related to several bird- and bat-associated densoviruses, sharing 97% to 98% identity. Meanwhile, the nucleotide similarity to a mosquito, cockroach, and cricket densovirus was 55%, 52%, and 41%, respectively. As this is the first described whole-genome characterization of a mealworm densovirus, we propose the name densovirus (DNV). In contrast to polytropic densoviruses, this DNV is epitheliotropic, primarily affecting cuticle-producing cells.
黄粉虫是大规模生产人类和动物营养所需的最重要的经济昆虫之一。浓核病毒对无脊椎动物具有高度致病性，并表现出极高的多样性，可与宿主相媲美。新型浓核病毒感染的分子、临床、组织学和电子显微镜特征具有极其重要的经济和生态意义。在这里，我们描述了商业黄粉虫（Tenebrio molitor）养殖场爆发的一种高死亡率浓核病毒病。临床症状包括无法摄取食物、不对称运动逐渐发展为无法行走、脱水、身体颜色变暗以及死亡。肉眼观察时，受感染的黄粉虫表现出发育不良、颜色变暗、幼虫身体弯曲以及器官/组织变软。组织学上，表皮、咽、食管、直肠、气管和细支气管中有大量上皮细胞死亡、巨细胞和巨核细胞，并有核内包涵体（InI）。超微结构显示，这些 InI 代表了一个浓核病毒复制和组装复合物，由直径为 23.79 至 26.99nm 的病毒颗粒组成，这在透射电子显微镜下可以观察到。全基因组测序确定了一种 5579 个核苷酸长的浓核病毒，包含 5 个开放阅读框。黄粉虫浓核病毒的系统发育分析表明，它与几种与鸟类和蝙蝠相关的浓核病毒密切相关，具有 97%至 98%的同一性。同时，与蚊子、蟑螂和蟋蟀浓核病毒的核苷酸相似性分别为 55%、52%和 41%。由于这是首次对黄粉虫浓核病毒进行全基因组特征描述，我们提议将其命名为 浓核病毒（DNV）。与多嗜性浓核病毒不同，这种 DNV 是上皮嗜性的，主要影响产生角质层的细胞。
