Spontaneous mutants of the adenovirus-simian virus 40 hybrid, Ad2 +ND3, that grow efficiently in monkey cells

Abstract

An attempt was made to isolate spontaneous mutants of adenovirus type 2 and of the adenovirus-SV40 hybrids, Ad2 +ND3 and Ad2 +ND5, that would grow efficiently on monkey cells. Virus stocks were serially passaged through the semipermissive established monkey libe CV-1. After five serial passages in the absence of intentional mutagenesis, only stocks of Ad2 +ND3 yielded significant numbers of variants that plaqued with similar efficiency on human and on monkey cell monolayers. Four independent Ad2 +ND3 variants, designated hr600, hr601, hr602, and hr603, have been isolated and partially characterized. Each grows and plaques on CV-1 monolayers with at least 100-fold greater efficiency than does the parent Ad2 +ND3. No differences was found between the genomes of these variants and the genome of parental Ad2 +ND3 by restriction enzyme analysis or by the analysis of heteroduplexes between Ad2 +ND3 (or variant) DNA and DNA of the hybrid Ad2 +ND1. Monkey cells infected with each of the variants synthesize as much fiber protein and component IIIa protein as do monkey cells productively infected with Ad2 +ND1. Phenotypically, these variants resemble adenovirus 2 host-range variants selected by Klessig ( J. Virol. 21, 1243–1246, 1977) after nitrous acid treatment of adenovirus 2 stocks.