Acta Veterinaria et Zootechnica Sinica ›› 2020, Vol. 51 ›› Issue (10): 2481-2489.doi: 10.11843/j.issn.0366-6964.2020.10.016

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Immune Effect of Inactivated Vaccines against Foot-and-Mouth Disease and Their Interference on Differential Diagnosis

SUN Pu1, HE Wei1,2, FU Yuanfang1, LI Dong1, YANG Lin1, WEI Delong1, CAO Yimei1, LI Pinghua1, BAI Xingwen1, MA Xueqing1, LI Kun1, BAO Huifang1, ZHANG Jing1, ZHU Xinrong3, LIU Zaixin1*, LU Zengjun1*   

  1. 1. State Key Laboratory of Veterinary Etiologic Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730046, China;
    2. Animal Medical School of Gansu Agricultural University, Lanzhou 730070, China;
    3. Gansu Holstein Cow Breeding Center, Lanzhou 730086, China
  • Received:2020-04-10 Online:2020-10-25 Published:2020-10-26

Abstract: Vaccination with inactivated vaccine is an important measure to prevent and control foot-and-mouth disease (FMD), however, the immune effect and antigenic purity of inactivated vaccines are two major concerns for the establishment and evaluation of FMD free zones with vaccination. In this study, four groups of FMD type O and type A bivalent inactivated vaccines from 3 FMD vaccine manufacturers (designated as A, B and C) were selected to inoculate healthy juvenile cattle of FMD free. All cattle were immunized 3 or 4 times at a 1-month interval. Serum samples were collected before and after 1 month of every vaccination to determine the level of antibody to structural protein and non-structural protein. Results:(1) The qualified rates of antibody to structural protein: in group a1 (vaccine from company A, different batches), the antibody qualified rate could reach 100% for type O and type A, respectively after each vaccination. In group a2 (vaccines from company A, same batch), the antibody qualified rates were 36.7%, 98.3% and 100% for type O, and 15%, 86.7% and 100% for type A after the first to the third vaccination, respectively. In group b (vaccine from company B, same batch), the antibody qualified rates were 18.3%, 97% and 100% for type O, and 1.7%, 45% and 53.3% for type A after the first to the third vaccination, respectively. In group c (vaccines from company C, same batch), the antibody qualified rates were 26.7%, 96.7% and 100% for type O, and 21.7%, 71.7% and 100% for type A after the first to the third vaccination, respectively. (2) Antibody positive rate to non-structural protein 3ABC (confirmed with second ELISA test): In group a1, the positive rates were 0.7%, 1.4%, 9.5% and 4.8% after the first to the fourth vaccination, respectively; In group a2 and c, no 3ABC antibody-positive animal was detected after 3 repeated vaccination; In Group b, only one animal with a positive rate of 0.6% was detected after the third vaccination. The antibody qualified rates to the structural protein of FMDV in 3 of the 4 groups were far less than 70% after the primary vaccination, however, those were increased significantly after boost and repeated vaccination. The antigen purity of vaccines in three groups (a2, b and c) can meet the requirement of OIE standard on the FMD vaccine, however, the seroconversion to 3ABC antibody was obvious in animals from group a1 after repeated vaccination, which would cause some extent of interference to differential diagnosis. Also, a combination of a primary screening test and a confirmatory ELISA test can further improve the accuracy of differential diagnosis. This study provides an important scientific basis to make a rational program for establishment and evaluation of FMD free zone with vaccination.

Key words: foot-and-mouth disease, inactivated vaccine, immune efficacy, antigen purity, differential diagnosis

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