Avian paramyxoviruses of PMV-3 serotype in British turkeys.

Serological testing of turkey flocks in Great Britain was undertaken as a result of the isolation of an avian paramyxovirus of serotype PMV-3 from turkeys in 1981 (Macpherson et al., 1983). Turkeys on two of four farms with egg production problems examined for PMV-3 haemagglutination inhibition (HI) antibodies in 1981 were positive. Turkeys on 34 farms were tested for PMV-3 antibodies in 1982. Seven of 16 flocks showing egg production problems and/or respiratory disease were considered positive for PMV-3 (mean log(2) HI titre >/= 2.5), but five of 18 flocks with no reported disease were also positive for PMV-3 antibodies. On one turkey farm the appearance of PMV-3 antibodies and an isolation of a PMV-3 virus coincided with egg production problems. Analysis of HI titres in turkeys vaccinated against Newcastle disease virus (NDV) and unvaccinated birds suggested that significant NDV HI titres are unlikely to be recorded as a result of PMV-3 virus infections of unvaccinated birds. However, while NDV vaccination prior to PMV-3 infection apparently caused slight suppression of the PMV-3 immune response, the HI titres to NDV were boosted considerably in direct relationship to the PMV-3 titre.