Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2012
Publication Date: 7/4/2012
Publication URL: http://handle.nal.usda.gov/10113/57542
Citation: Arafa, A., Suarez, D.L., Kholosy, S., Hassan, M.K., Abdel-Wanees, S., Selim, A., Dauphin, G., Kim, M., Swayne, D.E., Aly, M. 2012. Evolution of highly pathogenic avian influenza H5N1 viruses in Egypt indicating progressive adaptation. Archives of Virology. 157(10):1931-1947. Interpretive Summary: Since 2006, H5N1 highly pathogenic avian influenza (HPAI) has become established in Egypt. Genetic analysis of hemagglutinin (HA) gene from the 2006-20122 HPAI viruses indicates there are two genetic groups, a classic group and a variant group. The classic group was seen mainly in village poultry and is closely related to the original 2006 viruses, but has been found in come commercial poultry since 2009. The variant group was seen mainly in vaccinated commercial poultry. The Egyptian H5N1 HPAI viruses continue to change overtime.
Technical Abstract: Highly pathogenic avian influenza (HPAI) virus of the H5N1 subtype was first diagnosed in poultry in Egypt in 2006, and since then the disease became enzootic in poultry throughout the country affecting the poultry industry and village poultry as well as infecting humans. Vaccination has been used as a part of the control strategy to help in controlling the disease. Epidemiological data with sequence analysis of H5N1 viruses is important to link the mechanism of virus evolution in Egypt. This study describes the evolutionary pattern of Egyptian H5N1 viruses based on molecular surveillance for the isolates collected from commercial poultry farms and village poultry from 2006 to 2011. Genetic analysis of hemagglutinin (HA) gene was done through sequencing of H5 gene. The epidemiological pattern of disease outbreaks in Egyptian poultry farms seems to be seasonal with no specific geographic distribution. The results of this study indicate that HPAI - H5N1 viruses are progressively evolving and adapting in Egypt. The Molecular epidemiological data revealed that there are two major groups of viruses; one is the classic group of subclade 2.2.1 and another variant group of 18.104.22.168 sublineage. Both groups are still circulates all over the country. The classic group is prevailing mainly in village poultry and showed fewer mutations compared to the originally introduced virus in 2006. From 2009 this group started to transmit back to commercial sectors. The variant group was distinguishable by late 2007 and was prevalent mainly in vaccinated commercial poultry and has continuously mutated with higher rate until 2010 and started to diminish in 2011. The Egyptian viruses continue to acquire new mutations every season and adapted overtime.