Distribution Of A Local Isolate Of Velogenic Newcastle Disease Virus In Organs Of Infected Chickens

Abstract

The distribution of a local isolate of velogenic Newcastle disease virus (NDV) in internal organs of experimentally infected chickens was studied. A total of 118 white cockerels were used for the study. At six weeks of age, they were divided into two groups of 80 (infected group) and 38 (control group). Birds in the infected group were challenged each with 0.2ml of a local isolate of velogenic guinea fowl-1 (VGF-1) NDV, containing embryo infective dose 50% end point per ml (EID 50) of 106.36 obtained from Vom, Nigeria. Birds in the control group were inoculated with 0.2ml of phosphate buffered saline. Internal organs such as spleen, proventriculus, bursa of fabricius, lung and brain were collected from both groups on specified days post infection (PI) and pooled on the basis of organs. Tissues extracts prepared from the pooled organs were used to inoculate 10-day old embryonated chicken\'s eggs. Mortalities were recorded in the inoculated eggs between 24 and 72 hours post inoculation. This was used to estimate the viral concentrations on the specified days for the different organs examined. Results showed good concentrations of NDV in all the infected organs examined. The concentrations rose rapidly, and peaked by 7-10 days PI and thereafter decreased rapidly. There was no significant difference (p>0.05) in the mean viral concentrations between all the organs examined. It was concluded that all the internal organs examined had good viral load of the velogenic NDV during infection. It was suggested that the desire for organs for virus isolation in velogenic Newcastle disease (ND) should be based on the organs showing conspicuous or marked ND lesions. These samples should also be collected before day 10PI. Keywords: Newcastle disease virus, distribution, internal organs, virus isolation.Nigerian Veterinary Journal Vol. 28 (3) 2007 pp. 19-23