Infections due to Bombyx mori nucleopolyhedro virus ( Bm NPV) in commercially important silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) causes up to 50% loss to silk production in India. Increased resistance to NPV through introduction of double stranded RNA transgenes against multiple NPV genes is reported in B. mori . However, stability of the RNAi - mediated antiviral activity has not been determined after several generations of inbred transgenic B. mori . Hence, we examined the NPV multiplication rate and induction of the disease symptoms in NPV- infected transgenic and non-transgenic silkworm after 35 generations. Significantly higher multiplication rate of NPV supported by higher copy number of gp-41 gene was observed in non- transgenic larvae as compared to transgenic larvae. Expression of NPV genes, ie-1, lef1 and p74 enhanced significantly in non-transgenic larva as compared to transgenic larva after NPV infection. Strong positive correlation was observed in the expression pattern of NPV genes in transgenic larvae which was absent in non-transgenic larvae. This indicated co-regulation of NPV gene expression in the presence of transgenes.

中文翻译：

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近交转基因蚕中 NPV 基因表达模式的调节和基于 RNAi 的抗病毒活性的保留

家蚕核多角体病毒 (Bm NPV) 在具有重要商业价值的家蚕 Bombyx mori L.（鳞翅目：家蚕科）中引起的感染导致印度蚕丝产量损失高达 50%。在 B. mori 中报道了通过引入针对多个 NPV 基因的双链 RNA 转基因来增加对 NPV 的抗性。然而，在经过几代自交转基因家蚕之后，尚未确定 RNAi 介导的抗病毒活性的稳定性。因此，我们在 35 代后检查了 NPV 感染的转基因和非转基因家蚕的 NPV 繁殖率和疾病症状的诱导。与转基因幼虫相比，在非转基因幼虫中观察到由 gp-41 基因的更高拷贝数支持的 NPV 显着更高的增殖率。NPV基因的表达，即-1，与 NPV 感染后的转基因幼虫相比，lef1 和 p74 在非转基因幼虫中显着增强。在转基因幼虫中 NPV 基因的表达模式中观察到强烈的正相关，而在非转基因幼虫中则不存在。这表明在转基因存在下 NPV 基因表达的共调节。