【目的】 明确棉铃虫Helicoverpa armigera感染棉铃虫核型多角体病毒H. armigera nucleopolyhedrovirus（HearNPV）后显著上调表达的肠粘蛋白基因HaIIM5AC在抵御病毒侵染过程中的功能。【方法】 基于本实验室前期测定的健康及感病棉铃虫幼虫转录组数据，筛选出HearNPV感染后棉铃虫幼虫中显著上调表达的HaIIM基因，通过实时荧光定量 PCR（qPCR）技术分析其在健康和感病24、48、72和96 h幼虫中肠的表达水平，利用dsRNA注射法干扰感病幼虫的HaIIM5AC基因，统计感病幼虫的死亡速率并利用qPCR技术检测病毒量，利用石蜡切片和苏木素伊红染色观察围食膜形态，探究该基因在抵御HearNPV病毒侵染过程中的功能。【结果】 比较健康和感病棉铃虫幼虫肠道转录组差异基因，筛选出感病后24及48 h表达量均显著上调（P < 0.001）的肠粘蛋白HaIIM5AC基因。qPCR结果表明，与健康幼虫相比，感病幼虫中肠HaIIM5AC表达量在所有时间点均显著上调（24 hpi: P < 0.001; 48 hpi: P < 0.001; 72 hpi: P < 0.01; 96 hpi: P < 0.001）。RNAi实验结果表明，注射dsHaIIM5AC 24和48 h后，HaIIM5AC的表达量分别下调54.72%和43.48%。在幼虫中沉默HaIIM5AC后，感病幼虫的死亡速率显著加快（P < 0.05），病毒复制量显著增多（P < 0.001），中肠围食膜结构明显破损。【结论】 HaIIM5AC基因通过维持围食膜完整性来抵御HearNPV的侵染，其在棉铃虫抗病毒感染的物理免疫方面发挥重要作用。

To elucidate the function of the insect intestinal mucin gene HaIIM5AC in Helicoverpa armigera (the cotton bollworm) during infection by the Helicoverpa armigera nucleopolyhedrovirus (HearNPV). [Methods]  Significantly up-regulated HaIIM genes post-HearNPV infection were identified based on previously generated transcriptome data from healthy and HearNPV-infected H. armigera larvae. The expression level of HaIIM5AC in the midgut of healthy and infected larvae (24, 48, 72, 96 h post-infection [hpi]) was analyzed using quantitative real-time PCR (qPCR). RNA interference (RNAi) via dsRNA injection was employed to knock down HaIIM5AC expression in infected larvae. Mortality rates of infected larvae were recorded, and viral load was quantified using qPCR to investigate the role of HaIIM5AC in defense against HearNPV infection. In addition, paraffin sectioning and hematoxylin-eosin (HE) staining were used to observe peritrophic membrane (PM) morphology. [Results]  Comparative transcriptome analysis of healthy and infected larval midguts found that the HaIIM5AC gene had been significantly up-regulated 24 and 48 hpi (P < 0.001). Compared to healthy larvae, HaIIM5AC expression was significantly up-regulated in the midgut of infected larvae at all time points (24 hpi: P < 0.001; 48 hpi: P < 0.001; 72 hpi: P < 0.01; 96 hpi: P < 0.001). RNAi results showed that HaIIM5AC expression was reduced by 54.72% and 43.48% 24 and 48 hours after the injection of dsHaIIM5AC, respectively. Silencing HaIIM5AC resulted in significantly accelerated mortality rates in infected larvae (P < 0.05), significantly increased viral replication levels (P < 0.001), and obvious structural damage to the PM. [Conclusion]  The HaIIM5AC gene defends against HearNPV infection by maintaining the integrity of the PM, playing a crucial role in the immune response of H. armigera to HearNPV infection.