In order to investigate the lesions caused by two (H7N1, H7N3) low-pathogenicity avian influenza (LPAI) viruses isolated in turkeys during epidemics in Italy, 28 turkeys experimentally-infected by oro-nasal route and 2 negative controls were submitted to histopathological analysis. Hematobiochemical tests were also performed. Animals euthanized 4 days post-infection (DPI) revealed a moderate multifocal acute necrotizing pancreatitis (3/8). In animals euthanized 7-10 DPI major findings were a moderate-to-severe multifocal-to-diffuse chronic sclerosing pancreatitis and ductular hyperplasia (9/12). In turkeys euthanized 17-39 DPI (8/8) a multifocal moderate-to-severe lymphocytic fibrosing pancreatitis was observed. No lesions were detected in controls. Double-immunolabeled immunohistochemistry for glucagon and avian influenza virus revealed an occasional viral positivity of exocrine pancreas in turkeys euthanized 4-7 DPI whilst the glucagon presence was detected throughout the post-infection course. Immunohistochemistry for insulin revealed positivity in all sections taken from day 4 to 39 post-infection. Insulin-producing cells were more widely distributed than glucagon+ cells. Three out of six turkeys euthanized at 39 DPI were mildly hyperglycemic at 14 DPI and lowered blood glucose levels from 18 to 39 DPI; 4/6 turkeys at 7 DPI showed a marked increase of lipase level that lowered at 14 DPI. One of these 4 animals was also hyperglycemic and showed unusual and marked glucagon/insulin positivity within pancreatic interstitium. qRT-PCR confirmed the viral presence in pancreas in 2/8 animals euthanized at 4 DPI, in 5/5 turkeys euthanized at 7 DPI and in 1/6 turkeys euthanized at 9 or 10 DPI. In conclusion, we describe the post infection progression of specific pancreatic morphologic features and of endocrine cell expression, in turkeys experimentally infected with Italian LPAI viruses.
HISTOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL STUDY OF EXOCRINE AND ENDOCRINE PANCREATIC LESIONS IN AVIAN INFLUENZA A EXPERIMENTALLY-INFECTED TURKEYS
CAVICCHIOLI, LAURA;BEFFAGNA, GIORGIA;ZANETTI, ROSSELLA;ZAPPULLI, VALENTINA ELENA GIUDITTA;
2013
Abstract
In order to investigate the lesions caused by two (H7N1, H7N3) low-pathogenicity avian influenza (LPAI) viruses isolated in turkeys during epidemics in Italy, 28 turkeys experimentally-infected by oro-nasal route and 2 negative controls were submitted to histopathological analysis. Hematobiochemical tests were also performed. Animals euthanized 4 days post-infection (DPI) revealed a moderate multifocal acute necrotizing pancreatitis (3/8). In animals euthanized 7-10 DPI major findings were a moderate-to-severe multifocal-to-diffuse chronic sclerosing pancreatitis and ductular hyperplasia (9/12). In turkeys euthanized 17-39 DPI (8/8) a multifocal moderate-to-severe lymphocytic fibrosing pancreatitis was observed. No lesions were detected in controls. Double-immunolabeled immunohistochemistry for glucagon and avian influenza virus revealed an occasional viral positivity of exocrine pancreas in turkeys euthanized 4-7 DPI whilst the glucagon presence was detected throughout the post-infection course. Immunohistochemistry for insulin revealed positivity in all sections taken from day 4 to 39 post-infection. Insulin-producing cells were more widely distributed than glucagon+ cells. Three out of six turkeys euthanized at 39 DPI were mildly hyperglycemic at 14 DPI and lowered blood glucose levels from 18 to 39 DPI; 4/6 turkeys at 7 DPI showed a marked increase of lipase level that lowered at 14 DPI. One of these 4 animals was also hyperglycemic and showed unusual and marked glucagon/insulin positivity within pancreatic interstitium. qRT-PCR confirmed the viral presence in pancreas in 2/8 animals euthanized at 4 DPI, in 5/5 turkeys euthanized at 7 DPI and in 1/6 turkeys euthanized at 9 or 10 DPI. In conclusion, we describe the post infection progression of specific pancreatic morphologic features and of endocrine cell expression, in turkeys experimentally infected with Italian LPAI viruses.Pubblicazioni consigliate
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