Field evaluation of enzyme-linked immunosorbent assay for detection of antibody to African swine fever virus.

The enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to African swine fever virus was evaluated under field conditions in the Dominican Republic. A total of 3,402 swine serums were tested by ELISA. All ELISA-positive serums (n = 224) and 426 of 2,760 ELISA-negative serums were retested by indirect immunofluorescence (IIF). There were no antibodies to ASF virus detected by IIF in ELISA-negative serums. By IIF, antibodies were detected in only a small portion of the ELISA-positive serums. The specificity and sensitivity of ELISA and IIF were investigated and discussed. It appears that poor quality serums had an effect in ELISA results. Detection of immunoglobulin (Ig) G and IgM classes of antibodies in the ELISA and IIF-positive serums were also performed and related to longevity of African swine fever virus infection. The ELISA is recommended as an efficient method in testing large number of serums; positive results are to be retested by IIF.