EVANESCENT-WAVE FIBER OPTIC SENSOR FOR DETECTION OF LEISHMANIA-DONOVANI SPECIFIC ANTIBODIES IN SERA OF KALA-AZAR PATIENTS

An easy-to-use technique for detection of antibodies specific for the parasite L. donovani in human serum sample has been developed. The met hod is based on an evanescent wave generated from a tapered configurat ion of decladded optical fibre and does not require any volumetric mea surement. Tapered fibres are immobilized with the purified cell surfac e protein of L. donovani by covalent bonding. Treated fibres are incub ated with the patient serum for 10 min followed by incubation with goa t anti human IgG tagged FITC. Fluorescent intensity from the fibre has been shown to be proportional to L. donovani specific antibodies pres ent in the test sera. Direct readings can be obtained after signal enh ancement through a photomultiplier tube within 5 min. The system, when tested on 12 positive sera, did not show any false negative result. A lso, no false positive result was obtained with serum samples of patie nts infected with leprosy, tuberculosis, typhoid and malaria, showing the specificity of the sensor and efficacy of the technique. (C) 1997 Published by Elsevier Science Limited.