Two new variants of the Rhodococcus equi virulence plasmid, 90 kb type IIIand type IV, recovered from a foal in Japan

This report describes the discovery of two new virulence plasmid types from a crossbred foal with Rhodococcus equi pneumonia in Kumamoto died with sev ere R. equi pneumonia and ulcerative enteritis. R. equi was isolated in lar ge numbers and isolates from the foal were investigated for the presence of virulence-associated 15-17 kDa antigens (VapA) by colony blotting, using t he monoclonal antibody 10G5, and by gene coding for VapA by PCR. Plasmid DN As extracted from the isolates were digested with restriction endonucleases BamHI, EcoRI, EcoT221, and HindIII. The digestion patterns that resulted d ivided the plasmids of these isolates into two closely related types. The d igestion patterns were then compared with eight representative virulence pl asmid types (85 kb types I, II, III and IV, 87 kb types I and II, 90 kb typ es I and II), which have already been reported. None of the EcoRI and EcoT2 21 digestion patterns of the eight representative plasmids matched those of the two plasmid types. We tentatively designated these new plasmid types a s 90 kb type III and type IV, since HindIII and BamHI digestion patterns of the two plasmid types were identical with those of a 90 kb type I plasmid. This study, demonstrated that there are at least 10 distinct but closely r elated plasmids present in isolates from horses in the world. (C) 2001 Else vier Science B.V. All rights reserved.