Detection of transmissible viral proventriculitis and chicken proventricular necrosis virus in the UK

Abstract

Increasing evidence suggests that a new birnavirus, named chicken proventricular necrosis virus (CPNV), is the aetiological agent of transmissible viral proventriculitis (TVP). The present work aimed to explore the possible presence of both TVP and CPNV in the UK. Forty-four chickens showing TVP-compatible gross lesions were classified into three groups based on the histological lesions: (i) TVP-affected chickens: lymphocytic infiltration and glandular necrosis (n = 15); (ii) lymphocytic proventriculitis (LP)-affected chickens: lymphocytic infiltration without necrosis (n = 18); and (iii) without proventriculitis (WP): no lymphocytic infiltration or necrosis (n = 11). Nine proventriculi (seven out of 15 corresponding to TVP, and two out of 11 corresponding to LP) were positive for CPNV by reverse transcriptase polymerase chain reaction (RT-PCR). These results support the previously suggested idea of CPNV as causative agent of TVP. Moreover, these data show that CPNV can also be detected in a number of cases with LP, which do not fulfil the histological TVP criteria. Phylogenetic analysis of partial sequences of gene VP1 showed that British CPNV sequences were closer to other European CPNV sequences and might constitute a different lineage from the American CPNV. TVP cases with negative CPNV PCR results may be due to chronic stages of the disease or to the reduced PCR sensitivity on formalin-fixed paraffin-embedded tissues. However, involvement of other agents in some of the cases cannot totally be ruled out. As far as the authors are aware, this is the first peer-reviewed report of TVP as well as of CPNV in the UK, and the first exploratory CPNV phylogenetic study.

Identification of Transmissible Viral Proventriculitis (TVP) in broiler chickens in Poland

“…In single cases, hemorrhages were also noted in proventriculi mucosa. HP examination of proventriculi revealed (I) vacuolar degeneration and necrosis of glandular epithelium with pyknotic nuclei which all together created necrotic debris in dilated glandular lumen, (II) replacement of glandular epithelium by hyperplastic ductal epithelium and (III) moderate to severe, usually multifocal, lymphocytic infiltration ( Figures 3 and 4); these are the three main HP changes characteristic for TVP (Dormiotrio et al 2007, Grau-Roma et al 2016). …”

“…Histopathological lesions noted in the case of TVP concern exclusively the proventriculus and are characterized by the necrosis of epithelial glandular cells, strong lymphocytic infiltration in the lamina propria of the mucous membrane and -among the proventricular glands -by the hyperplastic and metaplastic changes of ductal epithelial cells of proventricular glands with successive substitution of epithelial glandular cells with hyperplastic epithelial cells of excretory ducts (Dormitorio et al 2007, Grau--Roma et al 2016.…”

“…Recent findings indicate that chicken birnavirus -called chicken proventriculitis necrosis virus (CPNV), is strongly associated with the development of TVP lesions (Guy et al 2011, Grau-Roma et al 2016.…”

Chicken proventricular necrosis virus related transmissible viral proventriculitis in broiler chickens in Poland

“…Recent research from the UK also suggests the involvement of CPNV in the development of TVP in chickens. In two studies, the authors reported that CPNV was detected in 22 and 47% of con rmed clinical cases of TVP [11,12]. It remains unknown, however, if all cases of this disease are of the same infectious origin.…”

Disease surveillance in England and Wales, April 2017

“…TVP is associated with a variety of clinical signs in broilers including poor growth and feed conversion. The causative agent is considered to be chicken proventricular necrosis virus (CPNV), and this virus has recently been demonstrated in histologically typical cases in the UK (Grau-Roma and others 2017). Colleagues should be aware that CPNV is a birnavirus and, by comparison with other birnaviruses, is likely to persist in the environment of poultry houses, potentially giving rise to infection in subsequent flocks.…”