[Distribution of virulence associated genes among strains of Leptospira]

To analyze factors related to the virulence associated genes of Leptospires.

Twelve putative virulence associated genes were detected by polymerase chain reaction (PCR) method in 38 reference strains, 81 field strains of Leptospira interrogans isolated from patients or animals, and 12 avirulent strains of Leptospira biflexa.

These putative virulent genes were widely distributed among the strains of Leptospira interrogans, but only few of them were detected in Leptospira biflexa. Gene lipL32 was detected in all strains of Leptospira interrogans. Distribution of gene lipL36 was varied significantly with detected rates from 0 to 90.91%. Gene la1608 had a positive rate of 87.50% for strains of serogroup Icterohaemorrhagiae, but was only detected in few strains of other serogroups with a range from 0 to 25.00%. Rate of detection on gene sphA was 17.65% in Leptospira interrogans, and was absent in serovar hardjo reference strain.

Results indicated that these genes might be of importance for the virulence and pathogenicity of Leptospira interrogans, while gene lipL32 might be one of the common antigens. Gene lipL36 might be involved in serogroup specificity with genetic diversity, but gene la1608 was as one of the genes with specificity for serogroup Icterohaemorrhagiae. However, serovar hadjo might hold quite different genetic characteristics when compared with the other serovars of Leptospires.