Observations on a chicken embryo lethal (CELO) virus

American Journal of Veterinary Research (Impact Factor: 1.34). 08/1957; 18(68):657-60.
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    • "The isolation of CELO virus, later classified as the European FAdV-1 reference strain, was first documented in the early 1950s and serological investigations showed widespread prevalence in chickens at that time (Yates and Fry, 1957). Natural and experimental studies indicated that infection with CELO of susceptible chickens proceeds without causing recognized disease symptoms (Cook, 1968; Clemmer, 1972). "
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    ABSTRACT: Gizzard erosion in broilers due to an infection with virulent fowl adenovirus serotype 1 (FAdV-1) is an emerging disease. Although experimental studies were performed, a possible prevention strategy was not reported so far. The present study was set up to determine (i) a possible influence of birds' age at time of inoculation on the pathogenicity of a European FAdV-1 field strain (PA7127), (ii) the virulence of a apathogenic FAdV-1 strain (CELO), and (iii) its capability to protect SPF broilers from adenoviral gizzard erosion caused by the field virus. Oral infection of birds with PA7127 at 1-, 10- and 21-days of life, resulted in reduced weight gain compared to non-infected birds, with significance for birds infected at day-old. Independent of the birds' age at time of inoculation, clinical signs appearing approximately one week after challenge coincided with gizzard lesions. Birds infected exclusively with CELO at the first day of life did not show any clinical signs or pathological changes in the gizzard, confirming the apathogenicity of this European FAdV-1. A similar result was obtained for birds orally infected at the first day of life with CELO and challenged three weeks later with the pathogenic PA7127 strain. Therefore, complete protection of adenoviral gizzard erosion in broilers by vaccination of day-old birds could be demonstrated for the first time, although virus excretion was detected post challenge. Establishment of an amplification refractory mutation system quantitative PCR (ARMS-qPCR) facilitated the identification of the FAdV-1 strain and presence of challenges virus was confirmed in one sample.
    Full-text · Article · May 2014 · Veterinary Microbiology
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    • "The first avian adenovirus was isolated in 1949 when material from a case of lumpy skin disease in cattle was inoculated into embryonated chicken eggs [9]. Other early unintentional isolates of fowl adenoviruses were the chicken embryo lethal orphan (CELO) isolates made in embryonated eggs [10] and the GAL viruses from chicken cell cultures [11]. The first isolate of an avian adenovirus from diseased birds was from an outbreak of respiratory disease in bobwhite quail (Colinus virginianus) by Olson [12]. "
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    ABSTRACT: Avian Adeno viruses and Chicken Anemia Viruses cause serious economic losses to the poultry industry of Pakistan each year. Timely and efficient diagnosis of the viruses is needed in order to practice prevention and control strategies. In the first part of this study, we investigated broilers, breeder and Layer stocks for morbidity and mortality rates due to AAV and CAV infections and any co-infections by examining signs and symptoms typical of their infestation or post mortem examination. In the second part of the study, we developed a duplex PCR assay for the detection of AAV and CAV which is capable to simultaneously detect both the viral types prevalent in Pakistan with high sensitivity and 100% specificity.
    Full-text · Article · Sep 2011 · Virology Journal
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    • "Whereas adenoviruses can be found infecting all 5 major vertebrate classes (Davison et al., 2003) only Aviadenovirus that infects birds and Mastadenovirus that infect mammals have been well studied. Avian (fowl) adenovirus 1 or CELO (chicken embryo lethal orphan) virus was isolated in 1957 (Yates and Fry, 1957) and is responsible for mild respiratory pathologies in birds (Dubose and Grumbles, 1959). CELO virus can be isolated from healthy chickens, it does not cause visible disease when it is experimentally introduced into chickens (Cowen et al., 1978) and has not been associated with major economic losses or pathologies in chickens. "
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    ABSTRACT: There are more than 100 known adenovirus serotypes, including 50 human serotypes. They can infect all 5 major vertebrate classes but only Aviadenovirus infecting birds and Mastadenovirus infecting mammals have been well studied. CELO (chicken embryo lethal orphan) adenovirus is responsible for mild respiratory pathologies in birds. Most studies on CELO virus have focussed on its genome sequence and organisation whereas the structural work on CELO proteins has only recently started. Contrary to most adenoviruses, the vertices of CELO virus reveal pentons with two fibres of different lengths. The distal parts (or head) of those fibres are involved in cellular receptor binding. Here we have determined the atomic structure of the short-fibre head of CELO (amino acids 201-410) at 2.0 A resolution. Despite low sequence identity, this structure is conserved compared to the other adenovirus fibre heads. We have used the existing CELO long-fibre head structure and the one we show here for a structure-based alignment of 11 known adenovirus fibre heads which was subsequently used for the construction of an evolutionary tree. Both the fibre head sequence and structural alignments suggest that enteric human group F adenovirus 41 (short fibre) is closer to the CELO fibre heads than the canine CAdV-2 fibre head, that lies closer to the human virus fibre heads.
    Full-text · Article · Jul 2008 · Virology
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