Avian paramyxovirus serotypes 2-9 (APMV-2-9) vary in the ability to induce protective immunity in chickens against challenge with virulent Newcastle disease virus (APMV-1)

► We have evaluated cross-protection of APMV-2 to -9 immunized chickens against NDV. ► APMV-3 induced cross reacting antibodies and provided significant protection to NDV. ► APMV-2,-9 prior infection reduced mortality and clinical signs of NDV. ► APMV-4 to -8 prior infection did not provide significant protection to NDV. ► These results will have practical implications on NDV and APMV vaccination strategies.