en Virology Virology Original Research Original Research <strong>Background: </strong>Avian Influenza disease annually entails a significant economic loss to the poultry industry around the world. Influenza virus is a polymorphic virus of the orthomyxoviridae family (single-stranded RNA genome), and nucleoprotein (NP) is the structural and internal protein of the virus. The aim of the work was to purify nucleoprotein for further investigations with a simple, low-cost, fast and practical method.<br> <strong>&nbsp;&nbsp; Methods:</strong> In this study, H9N2 influenza virus was isolated in specific pathogen-free embryonated chicken eggs by allantoically inoculating 103 to 105 egg-infective doses (EID50) for 9 to 11 days, purified by 10% (W/V) polyethylene glycol (PEG) 6000 with a sucrose gradient of 60% to 30%. The influenza virus proteins were collected and prepared as fractions by preparative electrophoresis. Finally, the purified NP was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot procedures.<br> <strong>&nbsp;&nbsp; Results:</strong> The protein analysis with SDS-PAGE and silver nitrate staining indicated that the desired samples contained purified nucleoprotein and lacked other viral proteins. The results of the investigation of lyophilized fractions containing nucleoprotein on the SDS-PAGE revealed the absence of viral RNA in nucleoprotein and its high purity.<br> <strong>&nbsp;&nbsp; Conclusion:</strong> According to this study, purified nucleoprotein can be used to produce nucleoprotein vaccines, as well as to study structural, molecular and diagnostic and therapeutic materials. Avian influenza virus, H9N2, Nucleoprotein, Extraction, Purification 754 759 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-3061-1&slc_lang=en&sid=1 Seyedeh Saeedeh Hosseini EBRAHIM.MSPH@GMAIL.COM 200319475328460042311 200319475328460042311 No Department of Botany, Biotechnology and Bioinformatics, Payame Noor University, Tehran, Iran Kayvan Taheri 200319475328460042312 200319475328460042312 No Department of Biology, Microbiology, Azad University, Damghan, Iran Seyedeh Marzieh Hosseini 200319475328460042313 200319475328460042313 No Department of Biology, Microbiology, Azad University, Karaj, Iran Mehrdad Gholami mehrdad_gholami90@yahoo.com 200319475328460042314 200319475328460042314 No Department of Microbiology and Virology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran Ebrahim Kouhsari ekouhsari1987@gmail.com 200319475328460042315 200319475328460042315 No Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Elahe Edalati az1171355@gmail.com 200319475328460042316 200319475328460042316 Yes Department of Botany, Biotechnology and Bioinformatics, Payame Noor University, Tehran, Iran Rasoul Madani sabassian460@gmail.com 200319475328460042317 200319475328460042317 No Department of Botany, Biotechnology and Bioinformatics, Payame Noor University, Tehran, Iran Rokhsareh Mohammadzadeh rokhsare.mohamadzade@gmail.com 200319475328460042318 200319475328460042318 No Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Abed Zahedi Bialvaei abedzahedi@gmail.com 200319475328460042319 200319475328460042319 No Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Mohammad Sholeh m.sholeh1000@gmail.com 200319475328460042320 200319475328460042320 No Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Fariba Golchin Far moqarabzadeh@gmail.com 200319475328460042321 200319475328460042321 No Department of Botany, Biotechnology and Bioinformatics, Payame Noor University, Tehran, Iran