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Using three different assays, we examined 103 serum samples collected from different civet farms and a market in China in June 2003 and January 2004. While civets on farms were largely free from SARS-CoV infection, ≈80% of the animals from one animal market in Guangzhou contained significant levels of antibody to SARS-CoV, which suggests no widespread infection among civets resident on farms, and the infection of civets in the market might be associated with trading activities under the conditions of overcrowding and mixing of various animal species.

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 ...