Antigenic differentiation of avian pneumovirus isolates using polyclonal antisera and mouse monoclonal antibodies

Avian pneumovirus (AVP) isolates F83, CC220 and 1260 from Great Britain and 1556, 657/4, 2119 and 872/S from France, Hungary, Italy and Spain, respectively, were compared in ELISA and virus neutralization (VN) tests for reactions with chicken polyclonal sera against each of the viruses and monoclonal antibodies (MAbs) against two British isolates. ELISA test results using the polyclonal antisera indicated that all seven viruses were antigenically related, but some variation between strains could be detected, especially when antigens were prepared from infected cells using Nonidet P40 (NP40) rather than freezing and thawing. In VN tests results also showed that all viruses tested were related but there was evidence that the three British isolates showed closer relationships with each other than with the viruses from Italy, Hungary and Spain. In ELISA tests, isolates F83 and 1556 bound all 11 MAbs and 1260 reacted with 10/11 MAbs. Isolate CC220 showed reaction with all the MAbs but for 8/11 MAbs the optical density differences were low. Isolates 2119 and 872/S both reacted only with MAb 4 and none of the MAbs reacted with 657/4.