Experimental infection of duck origin virulent Newcastle disease virus strain in ducks.

Yabin Dai,Jianmin Zou,Chan Ding,Jianmei Li,Mei Liu,Xinyue Shen,Xu Cheng,Shengqing Yu

doi:10.1186/1746-6148-10-164

Abstract

BackgroundNewcastle disease (ND) caused by virulent Newcastle disease virus (NDV) is an acute, highly contagious and fatal viral disease affecting most species of birds. Ducks are generally considered to be natural reservoirs or carriers of NDV while being resistant to NDV strains, even those most virulent for chickens; however, natural ND cases in ducks have been gradually increasing in recent years. In the present study, ducks of different breeds and ages were experimentally infected with duck origin virulent NDV strain duck/Jiangsu/JSD0812/2008 (JSD0812) by various routes to investigate the pathogenicity of NDV in ducks.ResultsSix breeds (mallard, Gaoyou, Shaoxing, Jinding, Shanma, and Pekin ducks) were infected intramuscularly (IM) with JSD0812 strain at the dose of 5 × 108 ELD50. Susceptibility to NDV infection among breeds varied, per morbidity and mortality. Mallard ducks were the most susceptible, and Pekin ducks the most resistant. Fifteen-, 30-, 45-, 60-, and 110-day-old Gaoyou ducks were infected with JSD0812 strain at the dose of 5 × 108 ELD50 either IM or intranasally (IN) and intraocularly (IO), and their disease development, viral shedding, and virus tissue distribution were determined. The susceptibility of ducks to NDV infection decreased with age. Most deaths occurred in 15- and 30-day-old ducklings infected IM. Ducks infected IN and IO sometimes exhibited clinical signs, but seldom died. Clinical signs were primarily neurologic. Infected ducks could excrete infectious virus from the pharynx and/or cloaca for a short period, which varied with bird age or inoculation route; the longest period was about 7 days. The rate of virus isolation in tissues from infected ducks was generally low, even in those from dead birds, and it appeared to be unrelated to bird age and infection route.ConclusionsThe results confirmed that some of the naturally occurring NDV virulent strains can cause the disease in ducks, and that ducks play an important role in the epidemiology of ND. The prevention of NDV spread in ducks should receive more attention and research in terms of preventing the occurrence and prevalence of ND.

Highlights

Newcastle disease (ND) caused by virulent Newcastle disease virus (NDV) is an acute, highly contagious and fatal viral disease affecting most species of birds
Age susceptibility Gaoyou ducks of different ages infected with NDV JSD0812 strain either intramuscularly (IM) or intranasally (IN) and intraocularly (IO) showed clinical symptoms, but mortality rates varied with the age and inoculation route (Table 2)
Deaths usually occurred in ducks inoculated IM, and their mortality had a tendency to decrease with increasing age

Summary

Introduction

Newcastle disease (ND) caused by virulent Newcastle disease virus (NDV) is an acute, highly contagious and fatal viral disease affecting most species of birds. Newcastle disease (ND) caused by virulent Newcastle disease virus (NDV) isolates is an acute, highly contagious, and fatal viral disease affecting most species of birds [1]. It is one of the most important avian viral diseases because of its economic impact on the poultry industry. Ducks and geese are generally considered to be natural reservoirs or carriers of NDV while being resistant to NDV strains, even those most virulent for chickens [1]. Some isolates were pathogenic for ducks, and natural ND cases in ducks have been gradually increasing in recent years [10,11,14,16,17,18,19,21,23,24,25], indicating that ducks may be not just reservoirs and carriers of NDV and susceptible to infection with the disease

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