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

Kateri Bertran,Francesc Xavier Abad,Natàlia Majó,Marta Barral,Elisa Pérez-Ramírez,Júlia Vergara-Alert,Rosa Valle,Aida Chaves,Ayub Darji,Núria Busquets,Roser Dolz,Antonio Ramis,Ursula Höfle

doi:10.1186/1297-9716-42-24

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.

Highlights

In recent years, avian influenza has become one of the most important challenges that have emerged from animal reservoirs [1,2]
To date, most experimental studies on avian influenza are based on either chickens, turkeys or waterfowl species, while investigation into the ability of influenza A viruses to replicate in minor poultry species is scarce [6,8,9], and numerous aspects of the epidemiology of both low pathogenic avian influenza virus (LPAIV) and highly pathogenic avian influenza virus (HPAIV) in free-range raised poultry and game birds still remain unclear
All birds infected with H7N1 showed clinical signs that started at 3 dpi and consisted in depression, apathy and ruffled feathers

Summary

Introduction

Avian influenza has become one of the most important challenges that have emerged from animal reservoirs [1,2]. The current outbreaks detected in poultry and wild birds in many Asian, European and African countries are of concern to the poultry industry, in which they produce an economically devastating disease, and to public health [3] The potential of these viruses to cause a pandemic represents a constant threat to poultry, wild birds and humans worldwide, underlining the importance of avian reservoirs for any subtype of avian influenza virus. To date, most experimental studies on avian influenza are based on either chickens, turkeys or waterfowl species, while investigation into the ability of influenza A viruses to replicate in minor poultry species is scarce [6,8,9], and numerous aspects of the epidemiology of both LPAIV and HPAIV in free-range raised poultry and game birds still remain unclear

Methods

Results

Conclusion