Identification of the root-knot nematode, Meloidogyne incognita, using monoclonal antibodies raised to non-specific esterases

The esterase isozyme from Meloidogyne incognita with pI similar to 4.95 was purified using a Rotofor electrophoresis system. The purified enzyme was then used to raise monoclonal antibodies. Hybridoma cell lines producing antibodies were cloned and screened against the purified esterase in an enzyme-linked immunosorbent assay (ELISA). A selected monoclonal antibody was then tested by western blot analysis of crude soluble protein extracts of all the major species of Meloidogyne separated by native and SDS-PAGE electrophoresis. Although the antibody was cross-reactive in western blots of denatured proteins in the presence of SDS and in ELISA, it was not cross-reactive in western blots of native protein. The results demonstrate that a monoclonal antibody to a diagnostic non-specific esterase enables M. incognita to be discriminated from M. javanica without the need to separate the esterases by electrophoresis first. This is an approach which could be adopted in a number of situations where organisms can be identified by a diagnostic protein which has already been identified by electrophoresis