Autographa californica multiple nucleopolyhedrovirus core gene ac92 (p33) is required for efficient budded virus production

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac92 is a core gene encoding a protein associated with occlusion derived virus (ODV), binds human P53 and also has flavin adenine dinucleotide linked sulfhydryl oxidase activity but its role in the virus life cycle is not known. To determine ac92 function a deletion virus (vAc92KO) was generated and transfected Sf9 cells revealed that vAc92KO infection was restricted primarily to single cells and budded virus (BV) titer was reduced over 99.99%. However, viral DNA replication was unaffected and development of occlusion bodies in vAc92KO-transfected cells evidenced progression to very late phases of viral infection. AC92 localized to both the cytoplasm and nucleus, and was also associated with BV as well as ODV. In BV AC92 was detected in BV envelope and nucleocapsid fractions. Finally it was shown that the ac92 homologue from the Group II alphabaculovirus Mamestra configurata NPV maco96 could only partially rescue vAc92KO.