Isolation of avian infectious bronchitis coronavirus from domestic peafowl (Pavo cristatus) and teal (Anas)

Abstract

Coronavirus-like viruses, designated peafowl/China/LKQ3/2003 (pf/CH/LKQ3/03) and teal/China/LDT3/2003 (tl/CH/LDT3/03), were isolated from a peafowl and a teal during virological surveillance in Guangdong province, China. Partial genomic sequence analysis showed that these isolates had the S-3-M-5-N gene order that is typical of avian coronaviruses. The spike, membrane and nucleocapsid protein genes of pf/CH/LKQ3/03 had >99 % identity to those of the avian infectious bronchitis coronavirus H120 vaccine strain (Massachusetts serotype) and other Massachusetts serotype isolates. Furthermore, when pf/CH/LKQ3/03 was inoculated experimentally into chickens (specific-pathogen-free), no disease signs were apparent. tl/CH/LDT3/03 had a spike protein gene with 95 % identity to that of a Chinese infectious bronchitis virus (IBV) isolate, although more extensive sequencing revealed the possibility that this strain may have undergone recombination. When inoculated into chickens, tl/CH/LDT3/03 resulted in the death of birds from nephritis. Taken together, this information suggests that pf/CH/LKQ3/03 might be a revertant, attenuated vaccine IBV strain, whereas tl/CH/LDT3/03 is a nephropathogenic field IBV strain, generated through recombination. The replication and non-pathogenic nature of IBV in domestic peafowl and teal under field conditions raises questions as to the role of these hosts as carriers of IBV and the potential that they may have to transmit virus to susceptible chicken populations. INTRODUCTIONCoronaviruses (family Coronaviridae) belong to the order Nidovirales and contain a positive-stranded RNA genome that ranges from 27 to 31 kb in size (Cavanagh, 1997). Members of the family Coronaviridae infect a wide range of hosts and have been classified into three groups on the basis of antigenicity, genome organization and sequence similarity. Usually, coronaviruses infect only their normal target host species. It has, however, been reported that some strains of canine coronavirus and human coronavirus 229E can infect other, non-target species without causing disease (Barlough et al., 1984(Barlough et al., , 1985. The recent emergence of severe acute respiratory syndrome coronavirus (SARSCoV), which has been classified tentatively into group 2, has focused a great deal of interest on this virus family (Holmes, 2003). It was reported that SARS-CoV-like viruses were isolated from Himalayan palm civets (Guan et al., 2003) and ferrets (Mustela furo). Moreover, domestic cats (Felis domesticus) are susceptible to infection by SARSCoV, suggesting that the reservoir for this pathogen might involve a range of animal species (Martina et al., 2003).Infectious bronchitis virus (IBV), together with genetically related coronaviruses of turkey and pheasant, belongs to the group 3 coronaviruses. IBV is a pleomorphic, enveloped virus with club-shaped surface projections (spikes) and a single-stranded, positive-sense RNA genome of >27 kb in length (Boursnell et al., 1987). Upon virus entry into cells, a 39-coterminal nested set of six ...

Pathogenicity of a QX strain of infectious bronchitis virus in specific pathogen free and commercial broiler chickens, and evaluation of protection induced by a vaccination programme based on the Ma5 and 4/91 serotypes

“…This virus, identified as QX, was associated predominantly with various forms of renal pathology. Following this first report, other investigators have described the circulation of similar strains in China (Liu et al, 2005). Cuiping et al (2007) confirmed data presented by Liu et al (2005), reporting the isolation of nephropathogenic strains from vaccinated and unvaccinated chicken flocks between 2003 and 2005. A retrospective phylogenetic analysis on IBV strains isolated in Russia between 1998 and 2002 showed the isolation from a broiler farm of genetically related QX virus in the Far East of Russia in 2001 (near the border with China) (Bochkov et al, 2006).…”

Coronavirus avian infectious bronchitis virus

“…d The genome organisation, gene sequences and biological properties of these isolates were such that it is possible that they were actually IBVs; domestic fowl were kept nearby. The peafowl isolate of Liu et al [66] had > 99% genome sequence identity with the IB vaccine strain H120. The teal duck isolate caused disease when experimentally inoculated into chickens [66].…”

“…the peafowl but also in non-galliform birds e.g. the teal, which is a duck [66]. Indeed, some of the long-known mammalian coronaviruses have a wider host range than their name would suggest, and SARS-CoV is a case in point.…”

Coronaviruses in poultry and other birds

“…The isolate in China from a teal */also kept domestically, near chickens */had a spike protein that had Â/90% identity with some known IBV strains, including a nephropathogenic one (Liu et al ., 2005; databank accession number for the whole genome sequence, AY702975). When this isolate was inoculated into chickens, it caused disease, including kidney involvement.…”

“…The proteins of the peafowl virus had !/99% identity with the widely used IBV H120 vaccine (Liu et al ., 2005: databank accession number for the whole genome sequence, AY702085). This extremely high degree of identity makes it almost certain that it was the vaccine strain that had been recovered from the peafowl, which had chickens in the neighbourhood.…”