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Five strains of infectious bronchitis virus (IBV) were isolated from five layer flocks that had nephropathogenic infection in four provinces in China. Among them, three of the five flocks had been vaccinated against infectious bronchitis. Virulence studies indicated that the five Chinese IBV isolates caused 10 to 30% mortality in 15-day-old specific pathogen free chickens and gross lesions were mainly confined to the kidneys in all of the dead chickens. Two oligonucleotide pairs, S1Uni2 and S1Oligo3' or S1Oligo5' and S1Oligo3', were used after propagation of the isolates in embryonated eggs to amplify the S1 protein genes of the spike protein. The cDNA derived by reverse transcriptase-polymerase chain reaction was cloned and sequenced. The nucleotide and amino acid sequence of S1 protein gene had a similar degree of identity (> or =92%) among the five Chinese IBV isolates. The nucleotide and amino acid identity of the S1 protein gene between the five Chinese IBV isolates and 16 strains of other IBVs varied from 60 to 81%. This clearly showed that the five Chinese IBV isolates comprised a separate genotype. These results demonstrated, for the first time, that there is a new genotype of nephropathogenic IBV circulating in vaccinated and non-vaccinated flocks in China.

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.

Twenty-six avian infectious bronchitis (IB) viruses (IBV) were isolated from outbreaks in chickens in China between 1995 and 2004. They were characterized by comparison with twenty-six Chinese reference strains and five other IBV strains. Chinese IBVs, which were mainly nephropathogenic, were placed into seven genotypes. Fourteen Chinese IBV isolates were placed in genotype I, having small evolutionary distances from each other. Genotype II included 6 strains that were isolated in the 1990s in China. Genotype III consisted of eight Chinese isolates that showed close relationship with Korean IBV isolates. Another eight IBV isolates clustered in genotype IV and showed larger evolutionary distances. The Massachusetts serotype was present in China in 1990s and was in a separate genotype. Two isolates, HN99 and CK/CH/LHN/00I, which might be a reisolation of vaccine strains, clustered into genotype VI. Four Chinese IBV isolates formed another genotype and showed larger evolutionary distances from other Chinese IBV genotypes (genotype VII). IBVs in same genotypes showed more than 90% amino acid sequence similarities, whereas most of the viruses in different genotypes showed less than 90%. The results showed that IBVs in China came from genetic changes both in IBV populations that existed before the advent of vaccination and in the viruses that were introduced through live vaccines. IBVs showing various genetic differences are cocirculating in China.

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 ...

A comprehensive study of the epidemiology and pathogenicity of infectious bronchitis virus (IBV) in China was carried out by molecular characterization of the S1 gene from 46 isolates obtained for this study and 174 reference strains isolated over a 15-year period. Nine types were found according to sequence analysis and phylogenetic study of the S1 gene. The co-circulation of multiple IBV types and the ongoing emergence of IBV variants are the epidemiological challenges in China. Factors contributing to the continual emergence include mutations, insertions and deletions in the S1 protein genes; recombination between local IBV strains circulating in chicken flocks in China; and recombination between local strains and vaccine strains. Vaccination-challenge analysis between circulating field strains and Mass-type H120 vaccine indicated the need to develop new vaccines from local IBV strains. These results also emphasize the importance of continued IBV surveillance in China.

Severe acute respiratory syndrome (SARS) was caused by a novel virus now known as SARS coronavirus (SARS-CoV). The discovery of SARS-CoV-like viruses in masked palm civets (Paguma larvata) raises the possibility that civets play a role in SARS-CoV transmission. To test the susceptibility of civets to experimental infection by different SARS-CoV isolates, 10 civets were inoculated with two human isolates of SARS-CoV, BJ01(with a 29-nucleotide deletion) and GZ01 (without the 29-nucleotide deletion). All inoculated animals displayed clinical symptoms, such as fever, lethargy, and loss of aggressiveness, and the infection was confirmed by virus isolation, detection of viral genomic RNA, and serum-neutralizing antibodies. Our data show that civets were equally susceptible to SARS-CoV isolates GZ01 and BJ01.Severe acute respiratory syndrome (SARS) first appeared in Guangdong, China, in November 2002, and it subsequently spread to many parts of the world, making it the first major infectious disease outbreak of the 21st century (8,13,19). The etiological agent was a newly emerged and previously unrecognized coronavirus, now known as SARS coronavirus (SARSCoV) (2,3,(5)(6)(7)12), which is classified within the order Nidovirales, family Coronaviridae, genus Coronavirus (9,14,15). Epidemiological data obtained from the early stage of the SARS outbreak suggest an animal origin for SARS-CoV, although the reservoir host has yet to be identified (11,(20)(21)(22). The isolation of SARS-CoV-like viruses in masked palm civets and the relationship of their genomic sequences with those of viruses isolated from humans (1, 4) raise the possibility that civets play a role in SARS-CoV transmission to the human population. A striking difference between the vast majority of SARS-CoV genomes from humans and those from civets is the presence in the latter of an additional 29-nucleotide (nt) sequence 246 nt upstream of the start codon of the N gene. Only human SARS-CoV isolated from the earliest stage of the outbreak contains this same 29-nt additional sequence (1). In other words, most human SARS-CoV isolates had a 29-nt deletion in this region of the genome. Thus, while it is clear that SARS-CoV with and without the 29-nt deletion can replicate in humans, the influence of the 29-nt deletion on the capacity of the virus to replicate in civets has not been determined. Here we show that civets are equally susceptible to experimental infection with two different human SARS-CoV isolates, one containing and the other lacking the 29-nt sequence, and that all animals display clinical signs during the early stage of infection.SARS-CoV isolates GZ01 and BJ01 used in this study were originally isolated in Vero E6 cells at the Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China, and were propagated in Vero E6 cells for two additional passages at our institute in Harbin to generate virus stocks with titers of 10 6 50% tissue culture infective doses (TCID 50 )/ml. BJ01 has the 29-nt deletion found in most hu...

Newcastle disease virus (NDV) has a potential oncolytic effect due to its ability to induce apoptosis in tumor cells. However, previous studies have indicated discrepancies regarding the apoptosis signaling pathways induced by NDV in tumor cells. Here, we show that NDV infection induces simultaneous activation of intrinsic and extrinsic death pathways in A549 human lung cancer cells. In contrast, endoplasmic reticulum (ER) stress is not activated in NDV-induced apoptosis. We demonstrate for the first time that mitogen-activated protein kinase (MAPK) pathways are activated in NDV-infected A549 cells, and p38 MAPK is involved in NDV-induced cell death. Together, our findings provide novel insights into the underlying mechanisms by which NDV induces apoptosis in tumor cells.