Ecology of Avian Influenza Virus in Birds

Causey, Douglas; Edwards, Scott V.

doi:10.1086/524991

Cited by 79 publications

(83 citation statements)

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“…These result in adverse effect on the host pathogen relationship for AIV infection. These observations of the seasonal effect and environmental changes on avian influenza infections in chicken flocks were also explained by Douglas and Edurards [26].…”

Section: Oligonucleotide Primerssupporting

confidence: 64%

Surveillance on Avian Influenza H5N1 and H9N2 Subtypes In Egypt 2012-2013

MA¹,

Yi²,

Zeedy³

2014

Poult Fish Wildl Sci

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Surveillance on Avian Influenza Virus in Egypt during 2012 -2013 was undertaken to update the epidemiology of avian influenza virus infections among poultry flocks in Egypt. A total of 148 commercial chicken farms were tested by single-plex RT-PCR for direct detection of avian influenza viruses using type A specific nucleoprotein (NP) gene primer sets. The results revealed 5 positive chicken flocks infected with type-A AIV. These viruses were successfully isolated and propagated in SPF eggs. H5N1/HI test was positive only for three chicken flocks. Subtype specific (RT-PCR) revealed 3 positive H5 chicken flocks (2%) and 2 positive H9 chicken flocks (1.35%). All examined chicken flocks were negative for H7 subtype. Multiplex RT-PCR using H5, H7 and H9 subtypes specific primers confirmed these results. This shows the continuous co-circulation of the AIV H5 and H9 in commercial chicken flocks in Egypt complicating the respiratory problems in affected flocks. Egypt between 2012 -2013. Swabs were placed in 1-2 ml isotonic phosphate buffered saline (PBS) PH 7.0-7.4, chilled immediately on frozen gel packs and submitted to the laboratory as quickly as possible.Tracheal and cloacal swabs collected from each commercial poultry flock were pooled separately. Tracheal swabs were screened with RT-PCR for AIV detection, but cloacal swabs in PBS with antibiotics were subjected for virus isolation. AntiserumSpecific polyclonal antiserum against avian influenza subtype H5N1 was obtained from X-OVO (flock screen, Batch: 1/09) produced by OIE/FAO and National

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Section: Oligonucleotide Primerssupporting

confidence: 64%

Surveillance on Avian Influenza H5N1 and H9N2 Subtypes In Egypt 2012-2013

MA¹,

Yi²,

Zeedy³

2014

Poult Fish Wildl Sci

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“…and Campylobacter spp. (Reed et al 2003;Kruse et al 2004;Causey and Edwards 2008). We address these current gaps in knowledge by surveying natural allelic variation in five avian b-defensin (AvBD) genes at two levels: (1) intra-specific variation among mallard ducks (Anas platyrhynchos) from local and global populations; and (2) inter-specific variation among diverse members of the waterfowl; and discuss patterns of immunogenetic diversity in the light of evolutionary forces acting on these genes in waterfowl.…”

Section: Introductionmentioning

confidence: 99%

The Evolution of Innate Immune Genes: Purifying and Balancing Selection on β-Defensins in Waterfowl

et al. 2016

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In disease dynamics, high immune gene diversity can confer a selective advantage to hosts in the face of a rapidly evolving and diverse pathogen fauna. This is supported empirically for genes involved in pathogen recognition and signalling. In contrast, effector genes involved in pathogen clearance may be more constrained. b-Defensins are innate immune effector genes; their main mode of action is via disruption of microbial membranes. Here, five b-defensin genes were characterized in mallards (Anas platyrhynchos) and other waterfowl; key reservoir species for many zoonotic diseases. All five genes showed remarkably low diversity at the individual-, population-, and species-level. Furthermore, there was widespread sharing of identical alleles across species divides. Thus, specific b-defensin alleles were maintained not only spatially but also over long temporal scales, with many amino acid residues being fixed across all species investigated. Purifying selection to maintain individual, highly efficacious alleles was the primary evolutionary driver of these genes in waterfowl. However, we also found evidence for balancing selection acting on the most recently duplicated b-defensin gene (AvBD3b). For this gene, we found that amino acid replacements were more likely to be radical changes, suggesting that duplication of b-defensin genes allows exploration of wider functional space. Structural conservation to maintain function appears to be crucial for avian b-defensin effector molecules, resulting in low tolerance for new allelic variants. This contrasts with other types of innate immune genes, such as receptor and signalling molecules, where balancing selection to maintain allelic diversity has been shown to be a strong evolutionary force.

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“…(AHMAD et al, 2002;SULTANA et al, 2012). Wild birds have been found to transmit Newcastle Disease and Avian Influenza viruses, but other microbes may also be involved (PEARSON and McCANN, 1975;LI et al, 2004;CAUSEY and EDWARDS, 2008;HAFEZ and LIERZ, 2010;SAEED et al, 2012;SHABBIR et al, 2014). Ornithobacterium rhinotracheale (ORT) is a Gram negative bacterium that infects the respiratory tract, causes air sacculitis, pneumonia and mortality in domestic, as well as in wild birds (VAN EMPEL and HAFEZ, 1999; VAN VEEN, 2000;HAFEZ and LIERZ, 2010).…”

Section: Introductionmentioning

confidence: 99%