Genome sequence of SG33 strain and recombination between wild-type and vaccine myxoma viruses

Abstract

Myxomatosis in Europe is the result of the release of a South America strain of myxoma virus in 1952. Several attenuated strains with origins in South America or California have since been used as vaccines in the rabbit industry. We sequenced the genome of the SG33 myxoma virus vaccine strain and compared it with those of other myxoma virus strains. We show that SG33 genome carries a large deletion in its right end. Furthermore, our data strongly suggest that the virus isolate from which SG33 is derived results from an in vivo recombination between a wild-type South America (Lausanne) strain and a California MSD-derived strain. These findings raise questions about the use of insufficiently attenuated virus in vaccination.

Figure

Schematic comparison of SG33 nucleic acid similarities with Lausanne and California MSD/MSW myxoma virus (MYXV) strains. Nucleotide identities were calculated between SG33 and Lausanne open reading frames and between MSW available sequences and the corresponding SG33 sequences. Dotted lines, SG33 vs. Lausanne and MSD/MSW identity shifts. Gray box, SG33 deletion.