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Title: REPRODUCTION OF PROVENTRICULITIS IN COMMERCIAL AND SPF BROILER CHICKENS

Author
item Pantin Jackwood, Mary
item BROWN, T - UNIV OF GA - ATHENS, GA
item Huff, Geraldine

Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2005
Publication Date: 9/15/2005
Citation: Pantin Jackwood, M.J., Brown, T.P., Huff, G.R. 2005. Reproduction of proventriculitis in commercial and spf broiler chickens. Avian Diseases. 49:352-360.

Interpretive Summary: The proventriculus is the glandular stomach of birds. Proventriculitis is an infectious disease of chickens characterized by an enlarged proventriculus that is filled with fluid and feed, often rupturing during processing, contaminating the carcass and increasing the number of bacteria on the product. The cause of proventriculitis is not known. In this study, proventriculitis was studied by experimentally reproducing the disease in broiler chickens. One-day old commercial and specific pathogen free (SPF) broilers were fed proventricular homogenates produced from the proventriculi of broilers with proventriculitis. At 7 and 14 days after inoculation differences in weight gain, organ weights, and macro- and microscopic lesions between these birds and unexposed control birds were determined. Both commercial and SPF broilers had enlargement of the proventriculus with lesions in the proventricular glands. SPF broilers that were fed proventricular homogenates developed infectious bursal disease, and infectious bursal disease virus (IBDV) was detected by molecular techniques. They also were positive by molecular tests to a coronavirus (infectious bronchitis virus-IBV). Commercial broilers were negative for IBDV and positive for IBV. Both commercial and SPF chickens, were negative for other virus such as reovirus and Newcastle disease virus (NDV), and variably positive for adenovirus. Bacteria were not identified or isolated from affected proventriculus. Examination of thin sections of proventriculi using electron microscopy (EM) identified virus-like particles similar to coronaviruses. IBV was the only virus found by virus isolation in chicken embryos. In conclusion, the original proventricular homogenates contained IBDV, IBV, and adenovirus, but a causative role for these or other viruses in proventriculitis could not be proven and needs to be studied further.

Technical Abstract: Proventriculitis was studied by experimentally reproducing the disease in broiler chickens. One-day-old infectious bursal disease virus (IBDV) and infectious bronchitis virus (IBV) antibody positive commercial broilers, and one-day-old antibody negative SPF broilers were orally gavaged with proventricular homogenates produced from the proventriculi of broilers with proventriculitis. At 7 and 14 days post-inoculation differences in weight gain, organ/body weight ratios, and macro- and microscopic lesions between these birds and unexposed control birds were assessed. Both commercial and SPF broilers had enlargement of the proventriculus with necrosis of the glandular epithelium and lymphocytic infiltrates in the proventricular glands. SPF broilers exposed to the proventricular homogenates developed infectious bursal disease, and IBDV was detected by reverse transcriptase polymerase chain reaction (RT-PCR). They also were positive by RT-PCR to IBV (a coronavirus) and developed nephritis. Commercial broilers developed mild nephritis but not bursal disease, and were negative for IBDV and positive for IBV by RT-PCR. Both homogenate-inoculated commercial and SPF chickens, were negative for reovirus, and Newcastle disease virus (NDV) by RT-PCR, and variably positive for adenovirus by PCR. Bacteria were not identified in histological sections nor were they isolated from affected proventriculi. Indirect fluorescent antibody assay using convalescent sera detected intracytoplasmic staining in the proventricular glandular epithelial cells. Examination of thin sections of proventriculi using electron microscopy (EM) identified virus-like particles approximately 120 nm in diameter within the cytoplasma of these cells at 7 days post inoculation. These virus-like particles were similar to coronaviruses based on size, morphology and localization. Passage of proventricular homogenate filtrates in chicken embryos for virus isolation caused stunting, and allantoic fluid from these eggs was positive for IBV by RT-PCR. In conclusion, the original proventricular homogenates contained IBDV, IBV, and adenovirus, but a causative role for these or other viruses in proventriculitis could not be proven and needs to be studied further.