Comparative analysis of tetanus Antitoxin titers of sera from Immunized guinea pigs determined by Toxin neutralization test and enzyme linked Immunosorbent assay

The results of this project affirm the previous observations that in vitro system of assay like ELISA are more quick, sensitive, cost effective, appropriate. Further quantifications of antibodies is an added advantage. The findings that the reduction of animals used for potency of TT when compared to biological assay contributes to the advantages of using ELISA as a routine to assess potency of TT. A good correlation can be seen between titers of antibodies in neutralization toxin test and ELISA. Tetanus toxoid is one of the most used immunogens available to protect against tetanus. 1. A considerable reduction and retirement of the use of animals can be achieved by introduction of ELISA as a routine for potency of tetanus toxoid. 2. Substantial reduction of number of mice and quantitative data generated boosts up the image of in vitro assay. 3. ELISA is easy to perform, sensitive, highly reproducible and require only small quantities of sera and time saving and objective. From the study it was concluded that ELISA standardization done by me in the department of biological control (King Institute) is a promoting alternative to the biological potency assay of tetanus toxoid. Rapid technique in the based on application of ELISA. eg : Immuno comb can be standardized in future. Therefore the vaccine formulation did not influence the correlation between TN and ELISA titers of immunized guinea pig sera. Other workers have also reported good correlations between TN and ELISA titers of human sera.3 Simonsen et al. found good correlation between ELISA and TN titers of sera from vaccinated human populations but no correlation with sera from persons having an incomplete vaccination history. Our findings of a discrepancy between ELISA and TN titers of immunized animals early during the course of immunization have implications on the studies where antibody levels are measured by ELISA only. Therefore, we suggest that the ELISA titers of sera from immunized guinea pig or mice should be interpreted cautiously up to 6 weeks after a single immunization when the results are expressed as titers in weight units (μg/ml) or EAU/ml determined against a hyper-immune serum. To overcome the problem of discrepancies between ELISA and TN titers, one possibility may be the use of an ELISA reference serum (calibrated by TN test) with similar affinity antibodies or similar immunization status as the test serum