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

Abstract

A polyhedron morphology mutant of Autographa californica nuclear polyhedrosis virus, designated M5, was compared with wild-type virus by genotypic analysis with Eco RI, Bam HI, Hin dIII, Sst I, and Sma I restriction endonucleases. M5 DNA revealed several alterations relative to the wild-type pattern: (i) Eco RI fragment I was 400 base pairs larger; (ii) Bam HI fragment F was missing; (iii) Hin dIII fragment F was 400 base pairs larger; (iv) an extra restriction fragment was obtained with both Hin dIII and Sma I; and (v) Sst I 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 Eco RI fragment I and in Hin dIII 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.