Enzyme linked immunosorbent assay (ELISA) for detection of meningococcal antibodies in north India.

Serological response was studied in 16-30 years high risk age group, during the period December 1986-April, 1988, following meningococcal vaccine (Biomerieux, France). A total of 200 serum samples were collected from 50 individuals before vaccination and at 3 intervals of 1, 3 and 6 months post-vaccination respectively. Antibody response was measured by Enzyme Linked Immuno-Sorbent Assay (ELISA) and indirect haemagglutination assay (IHA). In the vaccinees antibody response by IHA test showed 56%, 82%, 78% and 74% positivity in the pre-vaccination, 1 month, 3 months and 6 months post vaccination samples. By ELISA 2%, 80%, 74% and 66% of the above groups showed serological response. Difference in the pre-vaccination and titres/O.D. of various post-vaccination groups was found to be statistically significant (p less than 0.001). There was, however, no significant difference (p greater than 0.05) amongst the titres/O.D. of three post-vaccination groups. Similarly acute and convalescent blood samples of 25 patients and one sample each of 31 contacts was studied for antibody response. In general, higher antibody titres are produced with systemic infection than with local nasopharyngeal infection or following vaccination.