en عمومى General پژوهشي Original article <div style="border-style: solid none border-top-color: windowtext border-top-width: 1pt border-bottom-color: windowtext border-bottom-width: 1pt padding: 1pt 0in"> <p class="MsoNormal" style="direction: ltr unicode-bidi: embed border: none padding: 0in"><b>Background and Aims:</b> Infectious bronchitis virus (IBV) causes an acute, highly contagious respiratory and kidney disease of chickens which results in significant economic losses in commercial broilers, layers and breeders. Rapid identification of IBV serotypes involved in respiratory complex is a problem in the differential diagnosis. <!--stripped--><!--stripped--></p> <p class="MsoNormal" style="direction: ltr unicode-bidi: embed border: none padding: 0in"><b>Materials and Methods:</b> In this study, a single and multiplex RT-PCR was used to detect group III, Massachusetts and 793/B serotypes of IBV that have been circulating in Iranian poultry industry since 1999. <!--stripped--><!--stripped--></p> <p class="MsoNormal" style="direction: ltr unicode-bidi: embed border: none padding: 0in"><b>Results:</b> Only seven out of 49 allantoic fluid samples showed positive results in single RT-PCR using group specific primers. Two of these samples belonged to IBV positive group in VN test. Whereas four samples belonged to H9N2 positive group and one sample belonged to IBV/AIV negative groups. The high sensitivity of single RT-PCR led to detect some of the missed IBV infections as compared with other virological tests. Three out of 7, IBV isolates identified with single RT-PCR, classified as 793/B serotype and four of them categorized as Massachusetts serotype in multiplex RT-PCR. <!--stripped--><!--stripped--></p> </div> <b><span style="font-size: 12pt font-family: 'Times New Roman', serif">Conclusion: </span></b><span style="font-size: 12pt font-family: 'Times New Roman', serif">The results indicated that multiplex RT-PCR method, can be a valuable test for rapid identification of Massachusetts and 793/B serotypes in complex respiratory complex infection of chickens.</span> Infectious bronchitis virus (IBV), Avian influenza virus (H9N2), Massachusetts, 793/B serotype, multiplex RT- PCR 24 29 http://journal.isv.org.ir/browse.php?a_code=A-10-1-13&slc_lang=en&sid=1 MM Rafiei 10031947532846002552 10031947532846002552 No Poultry Diseases Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, IranPoultry Diseases Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran M Vasfi-Marandi mvmarand@ut.ac.ir 10031947532846002553 10031947532846002553 Yes Poultry Diseases Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran MH Bozorgmehri-Fard 10031947532846002554 10031947532846002554 No Poultry Diseases Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran S Ghadi 10031947532846002555 10031947532846002555 No Poultry Diseases Section, Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran