1. Shahid Chamran University
102
Shahid Chamran University
Phylogenetic characterization of the partial hemagglutinin protein genes of three avian influenza viruses (H9N2) isolated in Ahvaz broiler flocks during
Zahra Boroomand1, Ramezan Ali Jafari2 and Mansour Mayahi 
Assistant Professor, Department of Avian Medicine, Faculty of Veterinary Medicine Shahid Chamran University of Ahvaz, Ahvaz, Iran
Associated Professor, Department of Avian Medicine, Faculty of Veterinary Medicine Shahid Chamran University of Ahvaz, Ahvaz, Iran
Professor, Department of Avian Medicine, Faculty of Veterinary Medicine Shahid Chamran University of Ahvaz, Ahvaz, Iran
Abstract :
objectives:Since 1998, Iranian poultry industry has been affected by avian influenza (AI) virus,subtype H9N2. The association of high mortality with these outbreaks in the field raised the specter of a possible new genetic modified AI virus.
Materials& methods: In this study, three AI viruses (H9N2) isolated from the broiler flocks with high mortality rates were characterized. The 488bp PCR products containing the midle site of hemagglutinin (HA) protein were generated and sequenced to determine molecular characterization of the isolates.
Result&conclusion:Sequence analysis of main region of HAl gene of three isolates showed that isolates were identical at the nucleotide as well as amino acid levels. Phylogenetic analysis of 488 bp nucleotide region of the PCR products revealed that Iranian AI viruses had very close relationship to each other indicating these came from the common source. Moreover, the maximum genetic similarity of these
viruses was observed with AI viruses from India, Tunisia, Israel, Iraq and United Arab Emirates, respectively. Overall, the results indicate that with the exception of some Chinese isolates the current status of Iranian AI viruses resembles to other Eurasian H9N2 viruses and in spite of different nucleotide sequences among the viruses there is no evidence for existence of new AI pathotype.
Key words: Avian influenza virus, Hemagglutinin protein, H9N2, Phylogenetic analysis
Introduction:
Avian influenza (AI) is a viral disease that infects both domestic and wild birds. The disease can result in a range of signs from a subclinical infection up to 100% mortality. Based on the pathogenicity of AI viruses in avian species, these viruses are pathotyped into highly pathogenic AI viruses and low-pathogenic AI viruses
(Capua & Alexander, 2006). The virus is transmitted by both direct and indirect contact between infected and susceptible birds (Easterday et al., 1997). AI viruses present a public health threat as a zoonotic pathogen, although the risk is considered low (Subbarao et al., 1998; Peiris et al., 1999; Koopmans et al., 2004).
The H9N2 AI subtype is circulating in the commercial poultry industry in the Middle East and Asian countries, causing high economic losses (Guo et al., 1999; Peiris et al., 1999; Lin et al., 2000; Butt et al., 2005). In Iran, the epidemic of H9N2 AI was first reported in 1998 (Nili & Asasi, 2003). In some of the infected farms the mortality rate was as high as 65%.
Material and methods:
In this study, three AI viruses (H9N2) isolated from the broiler flocks with high mortality rates were characterized. The 488bp PCR products containing the midle site of hemagglutinin (HA) protein were generated and sequenced to determine molecular characterization of the isolates.
Results:
Sequence analysis of main region of HAl gene of three isolates showed that isolates were identical at the nucleotide as well as amino acid levels. Phylogenetic analysis of 488 bp nucleotide region of the PCR products revealed that Iranian AI viruses had very close relationship to each other indicating these came from the common source. Moreover, the maximum genetic similarity of these viruses was observed with AI viruses from India, Tunisia, Israel, Iraq and United Arab Emirates, respectively. . The virus isolates used in this study were submitted to the GenBank sequence database and were assigned the accession numbers AIa:KP455989, AIc:KP and AId:KP
Discussion:
Overall, the results indicate that with the exception of some Chinese isolates the current status of Iranian AI viruses resembles to other Eurasian H9N2 viruses and in spite of different nucleotide sequences among the viruses there is no evidence for existence of new AI pathotype.
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amino-acid–based phylogenetic relationships of partial haemagglutinin gene of H9N2 virus isolated from Ahvaz, Iran. The sequences were obtained from GenBank.