Isolation and molecular identification of wild Newcastle disease virus isolated from broiler farms of Diyala Province, Iraq

Abstract

<jats:p>Background and Aim: Newcastle disease virus (NDV) remains a major viral disease of poultry. The morbidity and mortality rates of chickens vaccinated with NDV in broiler farms in Diyala Province were 100% and 80%, respectively, rates due to suspected infection with the highly virulent NDV. The present study aimed to isolate and identify the NDV virus and evaluate its pathogenicity in infected broiler chickens at poultry farms. Materials and Methods: Broiler chickens at two commercial poultry farms were suspected of being infected with virulent NDV due to high mortality rates. Virus isolated from samples of intestinal tissues, lungs, trachea, spleen, kidneys, and air sacs was adapted in the allantoic cavity of embryonated specific-pathogen-free (SPF) chicken eggs. The NDV pathotype was determined based on the mean death time (MDT) in eggs as well as the intracerebral pathogenicity index (ICPI) and intravenous pathogenicity index pathogenicity indexes of the isolated samples. Broilers were experimentally infected by inoculation with fluids collected from the allantoic cavities of 60 broilers aged 35 days. Serological and molecular tests were followed by enzyme-linked immunosorbent assay to determine levels of anti-NDV immunoglobulin G, and isolates were identified using a hyperimmune (HI) test and real-time polymerase chain reaction (RT-PCR). Results: Suspected and isolated NDV field samples propagated in the allantoic cavity of 10-day-old fertile SPF chickens were NDV positive in the rapid hemagglutination test within a few seconds. Pathogenicity indices and MDT showed that the isolated NDV was viscerotropic and velogenic. The virus was identified as NDV by the HI test using specific anti-LaSota HI serum and RT-PCR with specific primers and probes. Propagation of the virus in the allantoic cavity of embryonated hen eggs produced a viral titer of 109.5 EID50/0.1 mL. Conclusion: The virus isolated from broiler chicken farms in Diyala Province, Iraq, was viscerotropic and velogenic according to the pathogenicity indices and RT-PCR. The isolated NDV caused 100% morbidity and 90% mortality in NDV-vaccinated and experimentally infected broiler chickens.</jats:p>

Phylogenetic studies of Newcastle disease virus isolated from poultry flocks in South Sulawesi Province, Indonesia, in 2019

“…Most members of this class have low virulence abilities for chickens. On the contrary, class II isolates have a higher genetic diversity, ranging from avirulent and vaccine strains to highly virulent strains [ 3 , 18 ].…”

Partial Fusion (F) Gene Analysis of Newcastle Disease Virus Detected in Pakistan during 2021-2022

“…In 1926, in Java, Indonesia, and Newcastle upon Tyne, England, the first cases of Newcastle disease were documented, but now the disease is known to have spread worldwide. The World Organization for Animal Health has designated NDV infection as a reportable disease [1]. This infection is the thirdmost serious poultry disease and has been documented in 109 participating countries of the World Organization for Animal Health.…”

“…In the poultry industry, chickens and turkeys are more sensitive. In contrast, geese and ducks are resistant to NDV strains even the ones that are virulent for chickens, and are usually regarded as NDV carriers [1]. Extensive prevalence of NDV genotypes can infect commercial poultry and wild birds simultaneously but one genotype may persist in the population for a long time until replace by other newly emerged mutant.…”