Characterization of Three Infectious Bronchitis Virus Isolates from China Associated with Proventriculus in Vaccinated Chickens

Abstract

Outbreaks of an avian disease in infectious bronchitis-vaccinated chickens in China have led to the characterization of coronaviral isolates Q1, J2, and T3, which were isolated from proventricular tissues of the affected young layer flocks. Serologic analysis revealed that they could induce high titers of infectious bronchitis virus (IBV) antibodies in inoculated specific-pathogen-free (SPF) chickens in indirect enzyme-linked immunosorbent assay but were not neutralized by antisera specific to the IBV serotype M41 and the Australian T strain. In a pathogenicity experiment, the clinical signs and related gross lesions resembling those of field outbreaks were reproduced in SPF chickens, and viruses were reisolated from the damaged tissues, including trachea, proventriculus, duodenum, and cecal tonsil. Sequence data demonstrated the complete S1 amino acid sequences of these isolates were almost identical despite recovery from geographically different areas in China and had 47.3%-82.3% similarity in comparison with the 47 published S1 sequences. On the basis of genotyping and limited serology, the three isolates, which were responsible for field outbreaks of the disease, might be a new IBV variant.

Molecular studies of the Brazilian infectious bronchitis virus isolates

“…It was not possible to analyze viral tropism in old isolates (1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989) due to organs availability, since only samples of tracheas and lungs from chickens exhibiting respiratory distress and kidneys from birds presenting nephritis-nephrosis syndrome were available. Changes in IBV pathogenicity and tissue adaptation were previously reported in the literature, taking into account that genes N, S2, or M did not belong to the same serotype as the S1; however this matter is not fully understood (Yu et al, 2001a;b, Cavanagh, 2007;Mondal & Cardona, 2007).…”

Coronaviruses in poultry and other birds

“…These include much of the alimentary canal, as well as kidney, gonads and bursa. Pathology is not usually associated with infection of the alimentary tract by IBV, although proventriculitis has been attributed to strains of IBV (Yu et al ., 2001). It has long been known that some strains of the virus are highly nephropathogenic (Liu & Kong, 2004).…”

Comparison of the pathogenicity of QX-like, M41 and 793/B infectious bronchitis strains from different pathological conditions

“…The disease was diagnosed as infectious bronchitis and the associated virus was designated QX IBV (YuDong et al, 1998). Not much later, further diseases associated with either proventriculitis or severe kidney damage occurred in IBV-vaccinated flocks in many Chinese provinces (Yu et al, 2001;Liu & Kong, 2004). Egg production problems were also observed in some cases in the period between 1995 and 2004 (Liu & Kong, 2004).…”