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24 October 2015 A Real-Time Reverse-Transcription Polymerase Chain Reaction for Differentiation of Massachusetts Vaccine and Brazilian Field Genotypes of Avian Infectious Bronchitis Virus
Aline Padilha de Fraga, Nilo Ikuta, André Salvador Kazantzi Fonseca, Fernando Rosado Spilki, Eder Balestrin, Carolina Dias Rodrigues, Cláudio Wageck Canal, Vagner Ricardo Lunge
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Abstract

The avian infectious bronchitis virus is classified into serotypes or genotypes (or both) in different poultry-producing countries of the world. In Brazil, Massachusetts type (Mass), used as a live vaccine, and local field Brazilian variants (genotypes; BR) predominate in the commercial poultry flocks. This study describes the development and validation of two real-time reverse-transcription polymerase chain reactions (RT-qPCR) for the specific detection of Mass and BR genotypes in allantoic fluids and clinical samples. Genotype-specific primers, combined with a generic probe targeted to the S1 gene, originated Mass RT-qPCR and BR RT-qPCR–specific assays. Analytical sensitivity and linearity of these assays were determined in comparison with an IBV generic real-time RT-PCR based on the 5′ untranslated region (5′UTR RT-qPCR). Mass RT-qPCR detected five Mass field isolates, three vaccine samples, and one coinfected sample (BR and Mass) while BR RT-qPCR detected 16 BR field isolates. Both assays were linear (R2 > 0.98), reproducible, and as sensitive as the classical 5′UTR RT-qPCR used to detect IBV. In the analysis of 141 IBV clinical samples, 8 were positive for Mass RT-qPCR, 76 for BR RT-qPCR, and 2 for both assays. In the remaining 55 samples, 25 were positive only for 5′UTR RT-qPCR and 30 were negative for the three assays. In conclusion, both assays were able to detect Mass and BR genotypes, allowing rapid and easy IBV molecular typing from allantoic fluids and clinical samples.

© 2016 American Association of Avian Pathologists
Aline Padilha de Fraga, Nilo Ikuta, André Salvador Kazantzi Fonseca, Fernando Rosado Spilki, Eder Balestrin, Carolina Dias Rodrigues, Cláudio Wageck Canal, and Vagner Ricardo Lunge "A Real-Time Reverse-Transcription Polymerase Chain Reaction for Differentiation of Massachusetts Vaccine and Brazilian Field Genotypes of Avian Infectious Bronchitis Virus," Avian Diseases 60(1), 16-21, (24 October 2015). https://doi.org/10.1637/11262-081815-RegR.1
Received: 24 August 2015; Accepted: 1 October 2015; Published: 24 October 2015
KEYWORDS
Brazil
diagnosis
IBV
infectious bronchitis virus
molecular typing
variant
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