Newcastle Disease Virus Isolation and Its Prevalence in Uganda Poultry Farms

Abstract

The present research work was carried out to isolate andidentify Newcastle disease virus (NDV) by using haemagglutination inhibition(HI) test and HA-HI virus isolation, embryonated eggs (EE) and chicken embryofibroblasts (CEF). A total of 95 clinical (blood, tracheal and cloacal swabs)and post-mortem (brain, lung, colon and spleen) samples were collected fromchickens of field outbreaks of suspected Newcastle disease virus (NDV). The HIand HA-HI were employed to detect NDV in tissue homogenates of all the clinicaland post-mortem samples as well as laboratory samples (AF and ICF). Among the fourdifferent types of post-mortem samples, virus isolation rate was found to below in body organs. In CEF cell culture system, the rate of virus isolationfrom all the aforesaid samples was found to be at 100% with the exception ofserum samples; while in tracheal and cloacal swabs, it was at 90%; whilein serum, it was at 10%, in all clinical cases. The isolation rate ofNDV was higher in CEF culture system (66.7%) compared to that of avian embryos(33.3%). Samples were inoculated and the allantoic fluid (AF) of the deadembryos and the infected culture fluid (ICF) of the CEF were harvested at 24 to96 hours of the post-infection, respectively, which revealed that the virulentstrain of NDV is highly prevalent in the region. The prevalence of NDVwas established at 1.1%, 2.1% and 4.2% using HA-HI, EE, and CEF methods. Rapiddetection and identification of the virus are crucial for theeffective control of the disease as conventional diagnostic methods such asvirus isolation on embryonated eggs followed by serological identification inhaemagglutination-inhibition test are laborious and time-consuming. Thespeed of the diagnosis can be considerably increased by using methods based onmolecular biology, e.g. reverse transcription—polymerase chain reaction. However, thegenetic variability of APMV-1 isolates should be considered carefully as the potentialcause for false negative results of genetic-based laboratory tests.