CHARACTERIZATION OF A MYXOMA VIRUS-ENCODED SERPIN-LIKE PROTEIN WITH ACTIVITY AGAINST INTERLEUKIN-1-BETA-CONVERTING ENZYME

A genomic library of myxoma virus (MV) DNA, a leporipoxvirus that caus es myxomatosis, was constructed and screened by in vitro transcription -translation. A clone was selected on the basis of its strong reactivi ty with MV antiserum. Analysis of the corresponding DNA sequence and t he deduced amino acid sequence revealed an open reading frame coding f or a 34-kDa protein with strong homologies to members of the serpin su perfamily, The gene encoding this new protein, called serp2, was local ized on the MV genome. Interestingly, this gene is deleted in an atten uated strain. We constructed a baculovirus vector to produce recombina nt Serp2 protein and raised specific antisera that allowed the charact erization of Serp2 expression during the MV cycle. The biological rele vance of this new serpin from MV was monitored, and it was shown that Serp2 could inhibit human interleukin-1 beta-converting enzyme activit y.