IDENTIFICATION AND CHARACTERIZATION OF SEROGROUP-M AMONG NEPALESE ISOLATES OF DICHELOBACTER-NODOSUS, THE TRANSMITTING AGENT OF FOOTROT IN SMALL RUMINANTS

One thousand and sixty three isolates of Dichelobacter nodosus culture d between 1992 and 1996 from cases of footrot in sheep and goats of mi gratory flocks of Nepal were characterised by agglutination test using prototype antisera of the Australian classification system. Of those, sixty six isolates could not be classified into any of the nine serog roups (A-I). This study was therefore undertaken to characterise these isolates. It was established that they were agglutinated by antiserum against serotype M of an alternative classification system. The disti nct antigenic character of these isolates was further confirmed by DNA sequence analysis of the gene for the fimbrial subunit protein of two of them. At a molecular level, these isolates were closer to the prot otype of serogroup F, VCS 1017. However, when compared with VCS 1017, the number of amino acid substitutions (28) in the fimbrial protein of these isolates was similar to that expected between isolates of diffe rent serogroups. Because these isolates are antigenically similar to ' serotype' M, but meet all the criteria to be classified into an indepe ndent serogroup, it is proposed that these isolates together with isol ates previously classified as serotype M be classified as 'serogroup M '. (C) 1998 Elsevier Science B.V. All rights reserved.