Detection of circulating antigens in sera from visceral leishmaniasis patients using dot-ELISA

The anti-amastigote IgG antibodies were raised in rabbits purified and fractionated using the standard methods. From the same anti-amastigote IgG antibodies, a peroxidase conjugate reagent was prepared. Initially, the anti-amastigote IgG antibodies and their corresponding peroxidase conjugate reagents were analyzed with respect to their ability to recognise the homologous antigens. Thirty five serum samples from visceral leishmaniasis patients (VLP) were examined using dot-ELISA. In addition, thirty seven serum samples from either non-infected individuals or from patients infected with heterologous organisms were used to define the sensitivity and specificity of the test. Circulating antigens in 35 serum samples from VLP were successfully identified using dot-ELISA giving 100% sensitivity. With exception of serum samples from patients with Plasmodium vivax which shown cross-reactivity with Leishmania donovani antigens, the test appeared to be specific for the detection of circulating leishmanial antigens. Cross-reactivity was not observed with P. faciparum or Brucellosis.