[show abstract][hide abstract] ABSTRACT: Avian influenza viruses of the H9N2 subtype have seriously affected the poultry industry of the Far and Middle East since the mid-1990s and are considered one of the most likely candidates to cause a new influenza pandemic in humans. To understand the genesis and epidemiology of these viruses, we investigated the spatial and evolutionary dynamics of complete genome sequences of H9N2 viruses circulating in nine Middle Eastern and Central Asian countries from 1998 to 2010. We identified four distinct and cocirculating groups (A, B, C, and D), each of which has undergone widespread inter- and intrasubtype reassortments, leading to the generation of viruses with unknown biological properties. Our analysis also suggested that eastern Asia served as the major source for H9N2 gene segments in the Middle East and Central Asia and that in this geographic region within-country evolution played a more important role in shaping viral genetic diversity than migration between countries. The genetic variability identified among the H9N2 viruses was associated with specific amino acid substitutions that are believed to result in increased transmissibility in mammals, as well as resistance to antiviral drugs. Our study highlights the need to constantly monitor the evolution of H9N2 viruses in poultry to better understand the potential risk to human health posed by these viruses.
Journal of Virology 06/2011; 85(16):8413-21. · 5.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: An outbreak of highly pathogenic avian influenza (HPAI) virus subtype H5N1 was first diagnosed in a "backyard" flock of peafowl (Pavo cristatus) raised on palace premises in the Kingdom of Saudi Arabia in December 3, 2007. The flock consisted of 40 peafowl, and their ages ranged from 3 to 5 years old. Affected birds suffered from depression, anorexia, and white diarrhea. Four dead birds were submitted for HPAI diagnosis at the Central Veterinary Diagnostic Laboratory in Riyadh. Brain and liver tissues and tracheal and cloacal swabs were taken from the dead birds and processed for a real-time reverse transcriptase (RT)-PCR test and virus isolation in specific-pathogen-free embryonating chicken eggs. The H5N1 subtype of avian influenza virus was isolated from the four dead birds and identified by a real-time RT-PCR before and after egg inoculation. The virus isolates were characterized as HPAI H5N1 virus by sequencing analysis. Phylogenetic comparisons revealed that the H5N1 viruses isolated from peafowl belong to the genetic clade 2.2 according to the World Health Organization nomenclature. The peafowl H5N1 virus falls into 2.2.2 sublineage II and clusters with the H5N1 viruses isolated from poultry in Saudi Arabia in 2007-08.
[show abstract][hide abstract] ABSTRACT: The first outbreak of H5N1 highly pathogenic avian influenza (HPAI) in the Kingdom of Saudi Arabia (KSA) occurred in two "backyard" flocks of Houbara bustards and falcons in February 2007. Subsequent outbreaks were seen through the end of 2007 in "backyard" birds including native chickens, ostriches, turkeys, ducks, and peacocks. From November 2007 through January 2008, H5N1 HPAI outbreaks occurred in 19 commercial poultry premises, including two broiler breeder farms, one layer breeder farm, one ostrich farm, and 15 commercial layer farms, with approximately 4.75 million birds affected. Laboratory diagnosis of all H5N1-positive cases was conducted at the Central Veterinary Diagnostic Laboratory (CVDL) in Riyadh, Saudi Arabia. A combination of diagnostic tests was used to confirm the laboratory diagnosis. A rapid antigen-capture test and real-time reverse transcriptase-PCR (rtRT-PCR) assay on clinical and field specimens were conducted initially. Meanwhile, virus isolation in specific-pathogen-free embryonating chicken eggs was performed and was followed by hemagglutinin (HA) and hemagglutination inhibition tests, then rapid antigen-capture and rtRT-PCR tests on HA-positive allantoic fluid samples. In most HPAI cases, a complete laboratory diagnosis was made within 24-48 hr at the CVDL. Saudi Arabian government officials made immediate decisions to depopulate all H5N1-affected and nonaffected flocks within a 5-km radius area and applied quarantine zones to prevent the virus from spreading to other areas. Other control measures, such as closure of live bird markets and intensive surveillance tests on all poultry species within quarantine zones, were in place during the outbreaks. As a result, the HPAI outbreaks were quickly controlled, and no positive cases were detected after January 29, 2008. The KSA was declared free of HPAI on April 30, 2008, by the World Animal Health Organization.
[show abstract][hide abstract] ABSTRACT: Highly pathogenic influenza virus (HPAIV) H5N1 has caused mortality and morbidity in many species of domestic and wild bird. The Houbara bustard (Chlamydotis undulata macqueenii) is a solitary bird that inhabits semi-desert regions. It is known to be susceptible to avianpox, avian paramyxovirus type 1, and low-pathogenicity avian influenza H9N2. We report an outbreak of H5N1 HPAIV in Houbara bustards, which were introduced into the Kingdom of Saudi Arabia for falconry purposes. Ninety-three per cent mortality (38 out of 41 birds) in the infected Houbara bustard flock and about 62.5% mortality (10 out of 16 birds) in falcons that came in contact with these birds were observed. Pooled cloacal and tracheal swabs from Houbara bustards as well as visceral organ homogenates collected in Houbara bustards and falcons were tested by real-time reverse transcriptase-polymerase chain reaction, and virus isolation was attempted in specific pathogen free hens' eggs. The viruses isolated were characterized as HPAIV H5N1. Phylogenetic analysis of the haemagglutinating and Neuraminidase (NA) genes revealed that the viruses isolated from Houbara bustards and falcons were closely related to each other and to Kuwaiti H5N1 strains isolated in 2007. Interestingly, they were genetically distinguishable from the co-circulating A/H5N1 viruses in Kingdom of Saudi Arabia causing outbreaks in domestic birds. This case emphasizes the need for surveillance of this endangered species in its natural habitat.
[show abstract][hide abstract] ABSTRACT: Since early 2007, the Kingdom of Saudi Arabia (KSA) has experienced several highly pathogenic avian influenza (HPAI) H5N1 outbreaks in the falconry and poultry sectors. The public health threat associated with peculiar husbandry systems, requiring close contact between humans and birds of prey, highlights the need of an improved understanding of the epidemiology and of the viral characteristics of H5N1 viruses circulating in the region. Here we report molecular and phylogenetic analyses of H5N1 viruses isolated in the KSA in 2007 in distinct compartments of avian husbandry. From the results of our investigation it appears that two separate introductions into the different sectors occurred. The identification of specific amino acid mutations, which are described as genetic signatures of human influenza A viruses or known to confer resistance to antiviral drugs, raises concerns for the possible human health implications of the KSA H5N1 viruses.
Journal of General Virology 12/2008; 89(Pt 11):2691-7. · 3.13 Impact Factor