National Assay Report of the Food-and-Mouth Disease Inactivated Vaccine

HP Lin2*, F Lee1, SC Hu1, YF Tseng2, HY Yu2, SR Yeh2, RS Chen2

1Animal Health Research Institute, Council of Agriculture, Executive Yuan
2Animal Drugs Inspection Branch, Animal Health Research Institute, Council of Agriculture, Executive Yuan

Abstract

Foot-and-mouth disease is a highly contagious animal disease that results in severe economic losses in Taiwan and throughout the world. This study describes nationwide assays on 35 batches of imported foot-and-mouth disease inactivated vaccines from 2008 to 2013. All the vaccines were O serotype, composed of either O-Taiwan, O-Manisa or O-Campos strains. The fail rate of the 35 batches in passing the potency test was 5.8%. In order to understand the relationship between serum neutralizing antibody titers and protection, pigs vaccinated with 10 batches of these vaccines were challenged at 28 days post immunization. Results showed that only 6 of the 10 batches of vaccine could induce neutralizing antibody titers higher than 32 (our national assay standard) with protection rate >75% (12/16 protection rate, OIE standards). Pigs vaccinated with 4 out of 10 batches had neutralizing antibody titers lower than 32 and only 0% to 60% protection rates. In conclusion, results of the potency test using our national assay standard were similar to those of the OIE standard. The higher neutralizing antibody titers corresponded to the higher protection rates.

Keyword: foot-and-mouth disease, national assay, inactivated vaccine, neutralizing antibody titer, protection.