Validation of a commercial ELISA kit for the detection of rabies antibodies in dogs and cats for border qurantine in South Korea

Abstract

Rabies is a zoonotic disease which is reported as sporadic outbreak in South Korea. Although nation-wide vaccination program have been applied, stronger control management is required because of serial outbreaks in the rural areas surrounding the Seoul metropolis. Recently, several countries are requiring rabies neutralizing antibody test reports in the quarantine of dog and cat. The requirement has been applied in South Korea since December 1, 2012. Korean Government has adopted an OIE acknowledged standardized evaluation method, the Fluorescent Antibody Virus Neutralization Test (FAVNT). Recently, the need for a new test is rising due to some problems of the test to be used. As one of the tests, a commercial Enzyme-linked immunosorbent assay test (Platelia Rabies II kit, Bio-Rad) was evaluated by comparing with the standard method using 1,163 quarantine and 20 experimental serum samples. The specificity and sensitivity of ELISA test compared to FAVNT was 90.2% and 95.0% for dogs, 100.0% and 95.8% for cats and the k-values were 0.58 and 0.46 respectively. A further designed 20 experimental German Shepherds was evaluated for the FAVNT and ELISA tests on 0, 90 and 180 days post vaccination. On the 90 and 180 days post vaccination, three and seven dogs vaccinated with the inactivated vaccine were over 0.5 International Units (IU)/㎖, which was considered as the threshold of seroconversion to a rabies antigen, in FAVNT. However none of dogs was seropositive in ELISA test. In the group vaccinated with the attenuated vaccine, all of dogs had a titer of over 0.5 IU/㎖ for both methods except one dog in FAVNT. In quarantine tests, an inactivated vaccine is required to vaccinate because of the possibility of rabies virus infection. These results suggested that a commercial ELISA test still has limitation to apply quarantine inspection as a FAVNT replacement method in Korea situation despite of OIE recommendation.