Preparation and characterization of monoclonal antibodies against occluded virions of Bombyx mori nuclear polyhedrosis virus

Abstract

Six hybridoma cell lines secreting monoclonal antibodies (MAbs) to the structural polypeptides of occluded virions of Bombyx mori nuclear polyhedrosis virus (BmNPV) were established. These MAbs were characterized by immunoblot analysis and classified into three groups on the basis of their specificity to the viral polypeptides of occluded virions. MAbs classified as group 1 are reactive with occluded virion polypeptides exhibiting a smear pattern ranging in molecular weights (MWs) from 16,000 (16K) to 22K, but show no reactivity with the structural polypeptides of nonoccluded virions. In the BmNPV-infected cells, group 1 MAbs react with a single polypeptide with an apparent MW of 17K, suggesting that group 1 MAbs are directed against the 17K polypeptide or its counterpart present in the occluded virions. Group 2 MAbs react with two occluded virion structural polypeptides with MWs of 66 and 82K that are present in both nonoccluded virions and infected cells, and to a lesser extent, with six additional polypeptides of occluded virions. MAbs in group 3 consisting of four different species recognize the 40K polypeptide and one to five additional polypeptides ranging in MWs from 27 to 39K that are present in the infected cells but not detectable in the nonoccluded virions. In vitro translation of cytoplasmic RNA from infected cells and subsequent immunoprecipitation of translation products showed that polypeptides with MWs similar to those of the polypeptides additionally detected by group 3 MAbs were present among the immunoprecipitates. Immunofluorescence microscopy showed that localization of corresponding antigens in the infected cells differed distinctively among MAbs in the different groups.