Bombyx mori nucleopolyhedrovirus (BmNPV) is a pathogen causing Bombyx mori larval mortality and is also called grasserie disease (Lepidoptera: Bombycidae). Since this viral disease is not fully under control in sericulture, it is necessary to identify agents that can prevent or reduce the infection/proliferation of BmNPV in B. mori culture boxes. Sericultural activity is similar an agriculture, and the loss of cocoon production leads to economic losses. In this research area, we previously reported that the molecule Bm5 inhibits cathepsin activity from BmNPV (V-CATH) and protects infected B. mori larvae from liquefaction processes, limiting the spread of the disease. Here, we evaluated the efficacy of Bm5 in reducing sericultural loss due to BmNPV infection. Assays were carried out with B. mori fifth-instar hybrids immediately inoculated with BmNPV and Bm5 to prevent viral cathepsin action. The biological and productive variables relevant during larval development and cocoon productivity were analysed to verify the effectiveness of Bm5 treatment. Biological and economic parameter data showed that the larval survival rate of the BmNPV-infected and Bm5-treated groups was 35.6% higher than that of the untreated BmNPV group. In addition, the infected BmNPV and Bm5-treated groups showed surviving pupae that produced good-quality cocoons. The α- and β-esterase analysis from the midgut and fat body did not show a change in isoenzyme expression between Bm5-treated and untreated larvae infected with BmNPV. Therefore, the inhibition of viral cathepsin with the Bm5 was shown to be effective in reducing the loss of silk production from BmNPV-infected B. mori larvae.

家蚕核 多角体病毒（BmNPV）是一种引起家蚕幼虫死亡的病原体，也称为牧草病（鳞翅目：家蚕科）。由于这种病毒性疾病在养蚕业中并未得到完全控制，因此有必要找出能够预防或减少家蚕培养箱中 BmNPV 感染/增殖的药剂。蚕桑活动与农业类似，蚕茧生产的损失会导致经济损失。在该研究领域，我们之前报道过 Bm5 分子可抑制 BmNPV (V-CATH) 的组织蛋白酶活性，并保护受感染的家蚕幼虫免于液化过程，从而限制疾病的传播。在这里，我们评估了 Bm5 在减少 BmNPV 感染引起的蚕业损失方面的功效。对立即接种 BmNPV 和 Bm5 的家蚕五龄杂种进行测定，以阻止病毒组织蛋白酶的作用。分析了幼虫发育和茧生产力过程中相关的生物和生产力变量，以验证 Bm5 处理的有效性。生物学和经济参数数据显示，BmNPV感染组和Bm5处理组的幼虫存活率比未处理BmNPV组高35.6%。此外，受感染的 BmNPV 和 Bm5 处理组表现出存活的蛹，可以产生优质的茧。中肠和脂肪体的 α 酯酶和 β 酯酶分析未显示感染 BmNPV 的 Bm5 处理和未处理幼虫之间同工酶表达的变化。因此，用 Bm5 抑制病毒组织蛋白酶可有效减少 BmNPV 感染的家蚕幼虫丝产量的损失。