en تخصصي Special پژوهشي Original article <div><strong>Background and Aims:</strong> Human respirovirus 3 is the second most common agent for respiratory disease in children under five years old. Near 68% of respiratory tract infections belong to this type. However, there is no established vaccine for this virus. The aim of this study was to synthesize a DNA plasmid for HN gene of human respirovirus 3 (HPIV-3) as a first step for the preparation of a vaccine<span dir="RTL">. </span><br> <strong>Materials and Methods:</strong> The HN gene was synthesized and cloned into pcDNA3 plasmid. The plasmids were transformed into COS-7 cell lines. To evaluate the expressed HN protein, the western blotting assay was applied<span dir="RTL">. </span><br> <strong>Results:</strong> The HN protein 36 KD was detected on nitrocellulose membrane using anti-His-tag antibodies<span dir="RTL">. </span><br> <strong>Conclusions: </strong>We prepared a DNA plasmid containing HN gene of human respirovirus 3 to be used for the future studies towards making an effective vaccine. Among hospitalized Iranian children, one-month to five-year, human respirovirus 3 was most frequently observed in respiratory tract infection<span dir="RTL">. </span></div> DNA plasmid, Human respirovirus, Human parainfluenza, HN gene, cell culture 25 30 http://journal.isv.org.ir/browse.php?a_code=A-10-218-1&slc_lang=en&sid=1 D Behzadpour dbehzadpour@gmail.com 10031947532846006756 10031947532846006756 Yes Department of Virology, Rasht Branch, Islamic Azad University, Rasht, IR Iran. R Alizadeh 10031947532846006757 10031947532846006757 No Department of Genetics, school of medicine, Iran University of medical science, Tehran, IR Iran T Bamdad 10031947532846006758 10031947532846006758 No Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, IR Iran M Daliri 10031947532846006759 10031947532846006759 No National Institute for Genetic Engineering and Biotechnology, Tehran, IR Iran. A Seidavi 10031947532846006760 10031947532846006760 No Islamic Azad University, Rasht Branch, Rasht, Iran