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Pathogenesis and transmissibility of highly (H7N1) and low (H7N9) pathogenic avian influenza virus infection in red-legged partridge (Alectoris rufa).

Bertran K, Pérez-Ramírez E, Busquets N, Dolz R, Ramis A, Darji A, Abad FX, Valle R, Chaves A, Vergara-Alert J, Barral M, Höfle U, Majó N - Vet. Res. (2011)

Bottom Line: In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi.However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges.In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain. natalia.majo@cresa.uab.cat.

ABSTRACT
An experimental infection with highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian influenza virus (LPAIV) was carried out in red-legged partridges (Alectoris rufa) in order to study clinical signs, gross and microscopic lesions, and viral distribution in tissues and viral shedding. Birds were infected with a HPAIV subtype H7N1 (A/Chicken/Italy/5093/1999) and a LPAIV subtype H7N9 (A/Anas crecca/Spain/1460/2008). Uninoculated birds were included as contacts in both groups. In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi. The presence of viral antigen in tissues and viral shedding were confirmed by immunohistochemistry and quantitative real time RT-PCR (qRRT-PCR), respectively, in all birds infected with HPAIV. However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges. In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals. The present study demonstrates that the red-legged partridge is highly susceptible to the H7N1 HPAIV strain, causing severe disease, mortality and abundant viral shedding and thus contributing to the spread of a potential local outbreak of this virus. In contrast, our results concerning H7N9 LPAIV suggest that the red-legged partridge is not a reservoir species for this virus.

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Brain, 5 dpi; (A) Focal areas of malacia, H/E. (B) Positive staining in neurons, ependymal cells and glial cells, IHC.
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Figure 3: Brain, 5 dpi; (A) Focal areas of malacia, H/E. (B) Positive staining in neurons, ependymal cells and glial cells, IHC.

Mentions: Lesions in the digestive tract, liver, pancreas, kidney, adrenal gland, myocardium, breast muscle, Bursa of Fabricius and respiratory tract (Figure 2A) were mostly characterised by necrosis and light to moderate heterophilic infiltrates. Necrosis of the epidermal collar epithelial cells, in some cases in association with heterophilic infiltrate, was observed in feather follicles from 6 dpi onwards. In the brain, the most striking finding consisted in multifocal areas of malacia (Figure 3A). Evident necrosis of ependymal cells of the ventricles and epithelial cells of the choroid plexus was present. The cerebellum frequently showed multifocal areas of moderate chromatolysis of Purkinje neurons. Similar lesions were seen in the spinal cord from 6 dpi onwards; multifocal areas of mild spongiosis of the neuropil and neuronal chromatolysis, especially surrounding the medullary canal, were observed. In addition, some animals at 8 dpi showed focal heterophilic inflammatory infiltrate in the leptomeninges.


Pathogenesis and transmissibility of highly (H7N1) and low (H7N9) pathogenic avian influenza virus infection in red-legged partridge (Alectoris rufa).

Bertran K, Pérez-Ramírez E, Busquets N, Dolz R, Ramis A, Darji A, Abad FX, Valle R, Chaves A, Vergara-Alert J, Barral M, Höfle U, Majó N - Vet. Res. (2011)

Brain, 5 dpi; (A) Focal areas of malacia, H/E. (B) Positive staining in neurons, ependymal cells and glial cells, IHC.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045332&req=5

Figure 3: Brain, 5 dpi; (A) Focal areas of malacia, H/E. (B) Positive staining in neurons, ependymal cells and glial cells, IHC.
Mentions: Lesions in the digestive tract, liver, pancreas, kidney, adrenal gland, myocardium, breast muscle, Bursa of Fabricius and respiratory tract (Figure 2A) were mostly characterised by necrosis and light to moderate heterophilic infiltrates. Necrosis of the epidermal collar epithelial cells, in some cases in association with heterophilic infiltrate, was observed in feather follicles from 6 dpi onwards. In the brain, the most striking finding consisted in multifocal areas of malacia (Figure 3A). Evident necrosis of ependymal cells of the ventricles and epithelial cells of the choroid plexus was present. The cerebellum frequently showed multifocal areas of moderate chromatolysis of Purkinje neurons. Similar lesions were seen in the spinal cord from 6 dpi onwards; multifocal areas of mild spongiosis of the neuropil and neuronal chromatolysis, especially surrounding the medullary canal, were observed. In addition, some animals at 8 dpi showed focal heterophilic inflammatory infiltrate in the leptomeninges.

Bottom Line: In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi.However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges.In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain. natalia.majo@cresa.uab.cat.

ABSTRACT
An experimental infection with highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian influenza virus (LPAIV) was carried out in red-legged partridges (Alectoris rufa) in order to study clinical signs, gross and microscopic lesions, and viral distribution in tissues and viral shedding. Birds were infected with a HPAIV subtype H7N1 (A/Chicken/Italy/5093/1999) and a LPAIV subtype H7N9 (A/Anas crecca/Spain/1460/2008). Uninoculated birds were included as contacts in both groups. In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi. The presence of viral antigen in tissues and viral shedding were confirmed by immunohistochemistry and quantitative real time RT-PCR (qRRT-PCR), respectively, in all birds infected with HPAIV. However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges. In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals. The present study demonstrates that the red-legged partridge is highly susceptible to the H7N1 HPAIV strain, causing severe disease, mortality and abundant viral shedding and thus contributing to the spread of a potential local outbreak of this virus. In contrast, our results concerning H7N9 LPAIV suggest that the red-legged partridge is not a reservoir species for this virus.

Show MeSH
Related in: MedlinePlus