Pathogenicity of PMV-3/Turkey/England/Midland poultry holdings/1981 for chickens and turkeys.

The original 1981 English isolate of avian paramyxovirus type 3 from turkeys was of higher pathogenicity to chickens than the prototype 1968 isolate turkey/Wisconsin. It was lethal to chicks aged one day when given by intravenous or intracerebral inoculation. The age susceptibility was increased to one week by use of an inbred strain or betamethasone. The virus was more pathogenic to its natural host as outbred turkeys aged one week died after intravenous inoculation of the virus and contact transmission resulted in stunting and seroconversion of 2-week-old birds. Monoclonal antibodies to both viral glycoproteins, but not to the two internal proteins, protected one-day-old turkeys from 1000 intravenous LD50 of virus when they were inoculated one day after virus. This was considered to be analogous to maternally derived immunity and emphasised the role of yolk sac antibody in the protection of young stock.