Method Development and Validation of Identity Test for Meningococcal Conjugate Vaccine by Indirect ELISA
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Abstract
Background: An identity test is an important test that is performed on the meningococcal vaccine to verify its identity for quality control of the vaccine. The meningococcal conjugate vaccine consists of purified polysaccharides from Neisseria meningitidis, and each serogroup of meningococcal polysaccharide conjugates with a diphtheria toxoid carrier protein that corresponds to the registration dossier, so that vaccine recipients can be confident in the quality of the vaccine according to the product's standards. Therefore, the agency has expanded its ability to validate the identity of meningococcal vaccines. This testing has not been previously available for the quality control service of meningococcal conjugate vaccines.
Objective: To develop and validate method of the identity test of the meningococcal conjugate vaccine for use as standard methods in the laboratory.
Methods: The optimum conditions were determined by the specific reaction between the antigen and the antibody that was suitable for testing. In addition, the method validation was verified for two parameters, including specificity and intermediate precision.
Results: The results of the optimum conditions of the identity test for meningococcal conjugate vaccine by indirect ELISA showed that the optimum dilution level of each antibody has a specified dilution factor. The N. meningitidis antiserum group A was diluted at 1:10,000, while the N. meningitidis antiserum C, Y, and W135 groups were diluted at 1:5,000, respectively. In addition, this assay must be tested according to the designated plate templates so that it can be a valid analysis because each type of antigen has a specific antibody. Moreover, the result of the validation method was found that this method was highly specific to the reaction between antigen and antibody. These were calculated from the ratio values of each type of antigen, which presented the ratio values in the range of 17.69 - 40.78, while there were no specific reactions between antigen and antibody; the ratio values were very low, in the range of -0.02 - 4.95. Thus, the identity of each antigen can be determined, and there was no cross-reaction among the serogroups. The OD450 nm value of the blank was less than 0.1, which met the acceptance criteria. The results of intermediate precision by two independent analysts showed that the results of both analysts met the criteria, and the average ratios of standard substances and vaccine samples were not significantly different between the two analysts at the 95% confidence interval.
Conclusions: The results of the study revealed that the identity test for the meningococcal conjugate vaccine using the indirect ELISA technique met the requirements for validation. Therefore, it is suitable for use as a standard method for submitting the registration of the meningococcal vaccine in Thailand.
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