DETECTION AND SEQUENCE ANALYSIS OF LIG B AND LSA 21 GENES OF LEPTOSPIRES FIELDS ISOLATESM. ANANDACHITRA, V. JAYAKUMAR AND B. MURALI MANOHARAbstract Novel leptospiral antigens like Lig A, B and Lsa21 were identified through screening of genomic DNA expression libraries with patient and infected animal sera and appeared to be preferentially expressed during host infection. Hence, the present study was attempted to detect these immunogenic proteins in field isolated leptospires and compare their sequences with the published reference strains. Field isolates of leptospires were identified as L.interrogans serovar australis and L.interrogans serovar hebdomadis by RAPD-PCR and using reference serum. Lig B and Lsa 21 genes were amplified in both field isolated leptospires with the amplicon size of 1100 bp and 540 bp respectively. LigB nucleotide sequences were having 93-100% identity with LigB sequences of several L.interrogans serovars and strains and only 91-92% identity with L.krischneri serovars and strains. Lsa21 nucleotide sequences are having 100% identity with query coverage of 97-100% with the predicted hypothetical protein sequences of L.interrogans serovar copenhageni and Lai for which complete genome sequences are available. From this study, we interpret that Lsa21 is more conserved than LigB protein in leptospires. Predicted amino acid sequences of both sequences revealed that they consist of mainly beta-pleated sheet with no or less alpha helical secondary structure. These predicted proteins are more hydrophilic with less hydrophobic regions and are more antigenic. This study indirectly will help in the usefulness of these recombinant protein based serodiagnosis and vaccine research.
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