Standardization of an ELISA Format for the Detection of Trichomonas vaginalis Exo-Antigens in Vaginal Discharge.

¹Magda E Azab, ²Mohamed F Fikry, ¹Mohamed H Abdel Baki, ¹Fayza S Habib, ¹Khalifa E Khalifa and ¹Hala SI El-Wakil.

Departments of ¹Parasitology and ²Gynaecology & Obstetric, Faculty Of Medicine, Ain Shams University, Cairo, Egypt .

Trichomonas vaginalis exo-antigens was prepared by affinity purification from pooled supernatants of 15 isolated culture stocks with maximum growth in late logarithmic phase. The exoantigen was used for immunization of rabbits to obtain hyperimmune serum (HIS EXO). The serum was used in an enzyme-linked immunosorbent assay for the detection of Trichomonas vaginalis exo-antigens (ELISA EXO) in vaginal washout specimens. Checkerboard titration of different dilutions of pooled T. vaginalis positive and pooled negative vaginal washout specimens against different dilutions of anti-exoantigen/hyperimmune rabbit revealed that a vaginal washout dilution of 1/32 and an immune serum dilution of 1/200 were optimal for the running ELISA EXO. Amounts as little as 500 pg and 62 pg of somatic- and exo-antigens, respectively, diluted in pooled negative vaginal washout specimen were detected in the assay. This level of sensitivity corresponds approximately to 100-200 trophozoites/0.1 ml of undiluted specimen. None of the vaginal washout specimens obtained from patients complaining of vaginal discharge due to other causes as Chlamydia, Candida, non specific infections or malignancy reacted positively in ELISA EXO.