Deoxynucleotide sequence conservation of the endoflagellin subunit protein gene, flaB, within the genus Leptospira.

A Polymerase chain reaction was developed to amplify the entire open reading frame of flaB, the gene encoding the endoflagellin subunit protein. The 852 bp amplified products from 23 serovars of the genus Leptospira were subjected to restriction endonuclease analysis and the profiles correlated well with phylogenetic relationships between these serovars. The flaB deoxynucleotide sequences of L. hardjo-bovis, L. hardjo-prajitno and L. grippotyphosa were determined. The deduced primary amino acid sequences of each were highly conserved with only three amino acid residue differences observed. The deoxynucleotide sequences showed genetic drift with alternative bases in the third position of codons. The PCR product derived by amplification of flaB from L. grippotyphosa was cloned into the expression vector pGEX-2T and a recombinant FlaB fusion protein made. As predicted from the deduced amino acid sequences, the recombinant FlaB cross-reacted with heterologous antiserum derived from a rabbit infected with L. hardjo-bovis.