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Molecular characterization and comparison of reference and field strains of infectious bronchitis vírus

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Sueli da Silva Santos
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
Defense date:
Examining board members:
Leonardo José Richtzenhain; Paulo Eduardo Brandão; Enio Mori
Advisor: Leonardo José Richtzenhain

Infectious bronchitis is a viral disease, acute and highly contagious that affects birds of the Gallus gallus species, of all ages, causing huge economic losses due to mortality, drop in production and quality eggs. Differences between serotypes of IBV are due to variations in the amino acids sequence in S1 hypervariable region subunit of spike protein (S). This study aimed to partially sequence the S1 gene to determine the phylogenetic relationship between field and vaccine viral types, and to investigate circulating genotypes in Brazil. One hundred and sixty pool samples were collected from symptomatic flocks during 2009/2010. Each pool contained tissues from 3 to 5 birds and was composed by different organs (tracheas, lungs, kidneys, enteric contents, tract reproductive and tracheal swabs). Samples were screened for the presence of IBV using a nested RT-PCR targeted to the 3UTR. Positive samples (n=56) were submitted to a nested RT-PCR target to S gene resulting in 10 amplicons of 390pb that were then submitted to DNA sequencing and analysis. Brazilian IBV genotypes segregated in two phylogenetic groups: Massachusetts (Mass) and Brazilian types. Six samples clustered in the Mass group, with live attenuated vaccines used in Brazil. Four samples grouped with field Brazilian strains previously described (GeneBank accession: FJ791257 to FJ791273). In Mass cluster aminoacids identity range from 98% to 100%, suggesting vaccine virus detection, in this last case. Moreover, the verified identity between samples from this study and Mass group ranged 79% to 81%. Therefore the present study reinforces the emergence and circulation of news lineages of IBV in commercial Brazilian flocks, as well as the importance of consistent research and monitoring to better understand this phenomen and its consequences, aiming to improved control measures against the virus. (AU)

FAPESP's process: 09/12624-3 - Molecular characterization and comparison of strain of reference and scope of infectious bronchitis virus
Grantee:Sueli da Silva Santos
Support Opportunities: Scholarships in Brazil - Master