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This paper presents the first isolation of bovine respiratory syncytial virus in Brazil and its physicochemical, morphological and molecular characterization. The virus was isolated from 33 samples of nasotracheal secretions, successively inoculated into a Madin-Darby bovine kidney cell culture, which was characterized by physicochemical tests and morphological observation by electron microscopy. The Brazilian sample is an RNA pleomorphic, enveloped, thermolabile and nonhemagglutinating spicular virus. Reverse transcription, followed by nested polymerase chain reaction (nRT-PCR) assay was carried out using oligonucleotides B1, B2A, B3 and B4 for the fusion proteins (F) and B5A, B6A, B7A and B8 for the attachment protein (G). The nRT-PCR-F amplified a fragment of 481 bp corresponding to part of the gene that codes for protein F, whereas nRT-PCR-G amplified a fragment of 371 bp, in agreement with part of the G gene. The virus isolated from Brazilian samples in this study corresponded to the bovine respiratory syncytial virus, and RT-PCR proved to be useful for the diagnosis of bovine clinical samples.

-A dot-ELISA test for the detection of anti-BRSV antibodies is described. The objective of this study was the standardisation of a test as a fast, inexpensive and effective alternative to detect anti-BRSV antibodies. Its sensitivity, specificity and usefulness were compared to a commercial ELISA-kit and to the standard serum neutralisation (SN) test. The standardisation of the technique was done using nitrocellulose disks soaked with a viral sample isolated in Brazil, BRSV-25-BR. The best results were obtained when the disks were sensitised with a purified antigen at a concentration of 0.7 µg/disk and the bovine serum was diluted 1: 200. The experiment used 423 samples of bovine serum collected in the main cattle breeding centres in Brazil.

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