A new leptospiral serovar, ngavi, in the Tarassovi serogroup isolated from Zimbabwe oxen.

Two strains of the genus Leptospira, belonging to serogroup Tarassovi, were isolated from kidneys of apparently healthy oxen slaughtered at an abattoir in Zimbabwe. Both strains belonged to the same serovar but could not be assigned to previously known serovars using the cross-agglutinin absorption test. The name ngavi is proposed for the new serovar containing these two strains; strain SBF 16 is the reference strain. The Zimbabwe isolates showed some antigenic similarity to serovar gatuni when analyses were carried out using eight monoclonal antibodies, and had restriction patterns similar to those of serovars tarassovi, tunis, moldaviae and guidae when their chromosomal DNAs were analysed using RFLP analysis. The restriction patterns of the two strains could be distinguished from each other and from those of the four serovars when their Southern blots were hybridized with a probe synthesized from a repetitive sequence element cloned from serovar hardjo strain Hardjo-bovis.