Experimental infection of pheasants with a velogenic chicken isolate of Newcastle disease virus

Newcastle disease (ND) is a highly contagious infection of many avian species,causing enormous losses in poultry production worldwide. The objective of thisstudy was to reveal the clinical feature, virus shedding, and immune response followinginfection with a velogenic chicken isolate of Newcastle disease virus (NDV) insusceptible and vaccinated pheasants. Eighty dayold pheasant chicks were allottedto four groups. At 30 days of age, the birds in groups 1 and 3 were vaccinated withB1 strain via eye drop. Two weeks later, each bird in groups 1 and 2 was inoculatedwith 100 μL(50 μL/eye) of NDVinfected allantoic fluid containing 105 EID50 of viralinoculum. All groups were inspected daily for three weeks. Swab samples were takenat different time points and verifi ed for NDV infection by using reversetranscriptionpolymerase chain reaction (RTPCR). Serological examination was also madeby haemagglutinationinhibition assay. Clinically, watery mucoid feces was observedonly in one case among the vaccinated challenged birds, whereas the unvaccinatedchallenged birds showed anorexia, mild depression and head deviation. Out of 20birds in group 2, one case (5%) died. Based on RTPCR, virus shedding was onlyobserved among the unvaccinated birds from 5 to 14 days aft er challenge. The NDVwas detected more in tracheal swabs (40%) than in cloacal swabs (30%). The infectedbirds showed a high seroconversion. In conclusion, the velogenic NDV circulating inIranian chicken flocks has a low pathogenicity for pheasants, and ocular vaccinationwith B1 strain could provide a good protection.