Pathogenic and Immunohistochemical Studies of the HaSNPV Infected Helicoverpa armigera Larvae

Abstract：Here we report the pathogensis process of Helicoverpa armigera larvae infected with Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus(HaSNPV)using H．E staining and immunohistoc hemistry with an tibody against polyhedrin．The fourth instar Helicoverpa armigera larvae were injected with 5×l PFU HaSNPV per larva．H．E staining showed that no apparent pathogensis could be detected in all tissues at 24 hours post infection(hpi)．But at 48 hpi，the nucleus ofthe fat body an d trachea epidermis became swollen，an d the shape ofthe cells in these tissues were chan g~ ．At 72 h P i，significant hispathogensis were observed in fat body，trachea epidermis an d the epidermis，while no chan ges were found in midgut an d muscles．At 96 hpi，the constitution of the fat body，trachea and epidermis were destroyed．Th e immunohistoc hemistry results indicated the po lyhedrin protein could not be detected at 24 hpi．At 48 hpi，it was found partially expressed in the tissues of fat body，trachea epidermis an d epidermis．From 72 to 96 hpi，the po lyhedrin was found heavily expressed in fat body， trachea epidermis and epidermis．No po lyhedrin was found expressed in midgut untill larvae dead an d themusculewasnotbe infected allthetime．