Bromodeoxyuridine-induced mutants of Autographa californica nuclear polyhedrosis virus defective in occlusion body formation

Twelve temperature-sensitive (ts) and two morphology mutants of Autographa californica nuclear polyhedrosis virus were generated using the mutagen 5-bromo-2'-deoxyuridine (BrdUrd). The ts mutants grew normally at 25° C but exhibited abnormal occlusion body formation when grown at 33° C whereas the morphology mutants produced an abnormal cytopathic effect at 25° C and 33° C. None of the mutants was severely restricted for production of non-occluded virus; thus, with the eight ts mutants and the two morphology mutants incubated at 33° C the drop in titre was 0.5 to 3.0 log₁₀ from that at 25° C. The mutants fell into three groups based on the amount of polyhedrin synthesized at 25° C and 33° C in infected cells. The eight ts mutants were combined with ts mutants contructed in a previous series of experiments and the collection was sorted into complementation groups. The collection comprised ten groups and the new mutants were sorted into seven of these. It is concluded that gene products of these complementation groups have essential roles in occlusion body formation.