University of Khartoum

Avian Paramyxiovirus type-1 Infections of Pigeons: Serological, Virological and Immunological Studies

Avian Paramyxiovirus type-1 Infections of Pigeons: Serological, Virological and Immunological Studies

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Title: Avian Paramyxiovirus type-1 Infections of Pigeons: Serological, Virological and Immunological Studies
Author: Abdel Gadir Ballal Mohamed Ahmed, Ahmed
Abstract: Epidemiological, virological and immunological studies were conducted in two outbreaks of Newcastle like disease in pigeons in Khartoum and Atbara. The clinical signs were paresis, torticollis, head tremors, incoordination, inability to fly, diarrhoea and death. The Khartoum outbreak was characterized by a morbidity rate of 36.3% and a mortality rate of 15.3%. At Atbara outbreak the morbidity rate was 40% while the mortality rate was not recorded. Two virus isolates designated kh/94 and At/94 were isolated in embryonated chicken eggs from Khartoum and Atbara, respectively. Both virus isolates propagated in tracheal organ cultures as evidenced by cessation of ciliary movement and haemagglutination activity of their infected culture fluids. Both viruses agglutinated chicken and equine RBCs but not sheep RBCs. The haemagglutination activity for both isolates was inhibited by homologous and heterologous NDV antisera indicating that they were both avian paramyxovirus type-1 strains. The intracerebral pathogenicity index in day-old chicks was 1.53 for kh/94 and 1.00 for At/94 isolate while the intravenous pathogenicity index in 6 weeks old chickens were 1.05 and 1.01, respectively. In embryonating chicken egg, the mean death time of minimum lethal dose was 65 hours for kh/94 isolate and was 68 hours for At/94. The 50% embryo infection dose (EID50%) was 8.1 and 7.9 log10, respectively. Experimental infection of pigeons and chickens with kh/94 isolate indicated that the virus was highly virulent to pigeons while the ability to infect and cause disease in chickens varied. Among chicks experimentally infected, the day-old subgroups inoculated intraoculary and intranasally were highly susceptible as indicated by clinical signs and death. No clinical signs or death were observed in all other inoculated chicks although the virus was reisolated from these birds and measurable HI antibodies were detected. Virus shedding was recorded for 18 to 21 days from experimentally infected pigeons and for 12 to 14 days from experimentally infected chickens. The neurological adaptation of the virus was shown by virus recovery from the brain and the relatively high ICPI in day-old chicks. The distribution and shedding of the pigeon isolate kh/94 in the organs of experimentally infected chickens was the same as the classical form of NDV in chickens. The protective ability of Komarov and LaSota live NDV vaccines was investigated. Komarov live virus vaccine given intranasally was ineffective in young and adult pigeons and low levels of HI antibodies were detected. When vaccinated pigeons were challenged, 16.6% of adult pigeons resisted the challenge while none of the young vaccinated pigeons withstood the challenge. Moderate level of protection was recorded in adult pigeons vaccinated with LaSota live virus vaccine as 37.5% of the vaccinated pigeons resisted the challenge.
URI: http://khartoumspace.uofk.edu/handle/123456789/15210
Date: 2015-06-28


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