Development of an ELISA to detect antibodies to a protective lipopolysaccharide fraction of Leptospira borgpetersenii serovar hardjo in cattle

Monoclonal antibodies (Mabs) were produced against Leptospira borgpeterseni i serovar hardjotype Bovis antigens. A panel of 28 Mabs were characterised. Only the nine Mabs toward a lipopolysaccharide (LPS) fraction of 18, 24 kD a bands and a 26-28 kDa smear showed agglutinating, leptospiricidal and gro wth-inhibition activities, and passively protected hamsters against renal i nfection with hardjo. They also reacted strongly in the CH-ELISA, captured killed whole hardjo leptospires, gave good fluorescence in indirect FAT aga inst smears of hardjo culture and exhibited no cross reactivity with strain s in heterologous serogroups. On the basis of optimal activity in a range o f tests, one IgG class Mab (designated 25) was selected for use in an antib ody-capture ELISA system for the detection of bovine anti-hardjo antibodies . The system gave a wide separation of absorbance values between positive a nd negative sera at a 1:10 dilution. The antibodies detected by this assay an believed to be protective anti-LPS IgG. (C) 1999 Elsevier Science B.V. A ll rights reserved.