Application of the agar gel precipitin and virus neutralisation tests to the serological study of goose parvovirus.

An agar gel precipitin (AGP) test and virus neutralisation (VN) test were developed using antigens prepared in duck eggs, to detect and measure antibodies against goose parvovirus. The tests were evaluated using sera collected from the following sources; forty three-month-old geese that had survived Derzsy's disease as goslings, adult geese from a farm where an outbreak of Derzsy's disease had occurred in goslings 14 months earlier, geese that had received a duck embryo adapted goose parvovirus vaccine and parvovirus antisera donated by other laboratories. Of the Derzsy's disease survivors, eight of nine had high AGP and VN antibody titres throughout the observation period. Eight of 19 geese from a farm in which Derzsy's disease had occurred showed a positive VN antibody response, of which five also showed a positive AGP response. Virus neutralising antibodies were detected in all sera from the vaccinated groups compared with the AGP test which detected nine out of 20. Both tests detected high antibody levels in the parvovirus antisera from other laboratories. The findings suggest that the VN test was more sensitive in detecting low levels of antibody than the AGP test. However, the simple and inexpensive AGP test is a useful method of assessing the immune status of geese to Derzsy's disease.