Mapping the Mutation Site of an Autographa californica Nuclear Polyhedrosis Virus Polyhedron Morphology Mutant

A polyhedron morphology mutant of Autographa californica nuclear polyhedrosis virus, designated M5, was compared with wild-type virus by genotypic analysis with EcoRI, BamHI, HindIII, SstI, and SmaI restriction endonucleases. M5 DNA revealed several alterations relative to the wild-type pattern: (i) EcoRI fragment I was 400 base pairs larger; (ii) BamHI fragment F was missing; (iii) HindIII fragment F was 400 base pairs larger; (iv) an extra restriction fragment was obtained with both HindIII and SmaI; and (v) SstI fragment G was 400 base pairs larger. M5 virions contained two size classes of circular DNA, one of 100% of the wild type and one of about 58% of the wild-type molecule. A revertant of M5, designated M5R, was isolated on the basis of polyhedron morphology. The genome of M5R contained the insertion of DNA in EcoRI fragment I and in HindIII fragment F, but was similar to the wild type in its other restriction fragment patterns. M5-infected cell cultures synthesized a polyhedrin polypeptide smaller in size than the wild type or M5R.