Screening of pig sera for antibodies to Japanese encephalitis virus using a dot enzyme immunoassay and IgM capture ELISA: comparison with the hemagglutination inhibition and plaque reduction neutralization tests

A dot enzyme immunoassay for determination of antibodies to Japanese encephalitis virus was designed for use as a field technique for the surveillance of Japanese encephalitis virus activity among domestic pigs. The test was compared with the neutralization test and the hemagglutination inhibition test and found to be more sensitive than the hemagglutination inhibition test and comparable to the neutralization test in sensitivity but more simple to perform than either the neutralization or the hemagglutination inhibition tests. An IgM capture ELISA for the determination of JEV specific porcine IgM was also utilized to determine current infection rates in pigs. The tests which do not involve the determination of specific IgM are better used for testing sentinel animals for providing clues as to the rate of transmission of JEV among pigs. IgM tests determining acute infection are less likely to be useful unless animals are tested very frequently or if a great number of animals are tested at any one time.