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Avian Pathol: Coronaviruses in poultry and other birds.

The number of avian species in which coronaviruses have been detected has doubled in the past couple of years. While the coronaviruses in these species have all been in coronavirus Group 3, as for the better known coronaviruses of the domestic fowl (infectious bronchitis virus [IBV], in Gallus gallus), turkey (Meleagris gallopavo), and pheasant (Phasianus colchicus), there is experimental evidence to suggest that birds are not limited to infection with Group 3 coronaviruses. In China coronaviruses have been isolated from peafowl (Pavo sp), guinea fowl (Numida meleagris; also isolated in Brazil), partridge (Alectoris sp) and also from a nongallinaceous bird, the teal (Anas sp), all of which were being reared in the vicinity of domestic fowl. These viruses were closely related in genome organization and in gene sequences to IBV. Indeed, gene sequencing and experimental infection of chickens indicated that the peafowl isolate was the H120 IB vaccine strain, while the teal isolate was possibly a field strain of a nephropathogenic IBV. Thus, the host range of IBV does extend beyond the chicken. Most recently, Group 3 coronaviruses have been detected in greylag goose (Anser anser), mallard duck (Anas platyrhynchos) and pigeon (Columba livia). It is clear from the partial genome sequencing of these viruses that they are not IBV, as they have 2 additional small genes near the 3' end of the genome. Twenty years ago a coronavirus was isolated after inoculation of mice with tissue from the coastal shearwater (Puffinus puffinus). While it is not certain whether the virus was actually from the shearwater or from the mice, recent experiments have shown that bovine coronavirus (a Group 2 coronavirus) can infect and also cause enteric disease in turkeys. Experiments with some Group 1 coronaviruses (all from mammals, to date) have shown that they are not limited to replicating or causing disease in a single host. SARS-coronavirus has a wide host range. Clearly there is the potential for the emergence of new coronavirus diseases in domestic birds, from both avian and mammalian sources. Modest sequence conservation within gene 1 has enabled the design of oligonucleotide primers for use in diagnostic reverse transcriptase-polymerase chain reactions, which will be useful for the detection of new coronaviruses.

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Author:Cavanagh, D.
Publication:Journal of Avian Medicine and Surgery
Article Type:Reprint
Geographic Code:1USA
Date:Sep 1, 2006
Previous Article:Avian Dis: Ulcerative enteritis (quail disease) in lories.
Next Article:Avian Pathol: Detection of multiple strains of Pasteurella multocida in fowl cholera outbreaks by polymerase chain reaction-based typing.

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