Isolation and characterization of highly pathogenic avian influenza virus subtype H5N1 from donkeys

Submission date 2 February 2010
Publication date 14 April 2010

1 Department of Virology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-
Suef 62511 Egypt
2 Division of Virology, Department of Microbiology, College of Medicine and Medical
Sciences, Taif University, Al-Taif, Saudi Arabia
3 Department of Hygiene, Management & Zoonoses, Faculty of Veterinary Medicine,
Beni-Suef University, Beni-Suef 62511 Egypt
4 Department of Poultry Diseases, Faculty of Veterinary Medicine, Beni-Suef
University, Beni-Suef 62511 Egypt

Abstract
BACKGROUND: The highly pathogenic H5N1 is a major avian pathogen that crosses species barriers and seriously affects humans as well as some mammals. It mutates in an intensified manner and is considered a potential candidate for the possible next pandemic with all the catastrophic consequences.
METHODS: Nasal swabs were collected from donkeys suffered from respiratory distress. The virus was isolated from the pooled nasal swabs in specific pathogen free embryonated chicken eggs (SPF-ECE). Reverse transcriptase polymerase chain reaction (RT-PCR) and sequencing of both haemagglutingin and neuraminidase were performed. H5 seroconversion was screened using haemagglutination inhibition (HI) assay on 105 donkey serum samples.
RESULTS: We demonstrated that H5N1 jumped from poultry to another mammalian host; donkeys. Phylogenetic analysis showed that the virus clustered within the lineage of H5N1 from Egypt, closely related to 2009 isolates. It harboured few genetic changes compared to the closely related viruses from avian and humans. The neuraminidase lacks oseltamivir resistant mutations. Interestingly, HI screening for antibodies to H5 haemagglutinins in donkeys revealed high exposure rate.
CONCLUSIONS: These findings extend the host range of the H5N1 influenza virus, possess implications for influenza virus epidemiology and highlight the need for the systematic surveillance of H5N1 in animals in the vicinity of backyard poultry units especially in endemic areas.

Excerpts:
pg. 5/21:
Methods
Virus isolation
Nasal swabs were collected from three infected animals from Aborady village, El-Wasta locality, Beni-Suef Governorate.

pg. 8/21:
The disease recoded on 24th March 2009, 1wk after an outbreak of
H5N1 infection in poultry in the village, where many donkeys suffered from the same
clinical manifestations in an epidemic manner. The virus was isolated from a pool of
nasal discharge from three affected animals.

pg. 8/21:
The haemagglutinin gene was found to be closely related to
A/chicken/Egypt/0894-NLQP/2008, A/Egypt/N00605/2009 and
A/chicken/Egypt/092-NLQP/2009 while the neuraminidase gene of the current
strain is closely related to A/Egypt/N03450/2009 and A/Egypt/N05056/2009.
However, none of these strains were isolated from localities near to Beni-Suef.

pg. 10/21:
Conclusion
We did note the incidence of clinical infections of donkeys with HPAIV (H5N1) in
disease endemic regions where the probability of intimate contact between poultry
and donkeys is high. Furthermore, H5 seroconversion by naturally exposed donkeys
was evidenced. Although the disease did not constitute a real threat to donkeys, it
raises the concern of different issues including the route of transmission to donkeys,
whether being from aerosol exposure of pulverized infected birds droppings or
contaminated feeds and water or because of contact with infected birds. Second, the
role of donkeys in spreading H5N1 virus to birds, humans other mammals includingequines needs to be assessed.