Developing and Testing a Real-Time Polymerase Chain Reaction to Identify and Quantify Bovine Respiratory Syncytial Viruses

Molecular Characterisation and Antibody Response to Bovine Respiratory Syncytial Virus in Vaccinated and Infected Cattle in Turkey

Bovine respiratory syncytial virus (BRSV) is one of the most important respiratory pathogens of cattle. In this study, frequency of infection, analysis of variants, and the immune status of vaccinated and non-vaccinated cattle were studied. Blood (n = 162) and nasal/oropharyngeal (n = 277) swabs were collected from 62 cattle herds in Turkey. Lung samples (n = 37) were also taken from dead animals and abattoirs. Antibodies to BRSV were detected in 76 (46%) out of 162 sera. The antibody levels in the vaccinated and non-vaccinated groups were statistically significant. Among 277 nasal/oropharyngeal swabs and 37 lungs, ten nasal/oropharyngeal and four lung samples were positive for BRSV-RNA. BRSV-G gene sequences of 5 out of 14 RT-PCR positive samples showed that all viruses clustered as Group-III in phylogenetic analysis with 88-100% homology. Similarity with previous Turkish BRSVs was 89-98%, and that with BRSVs detected in the USA and Czechia was 89.47-93.12%. BRSV continues to circulate in Turkish cattle, and vaccination seems beneficial in preventing BRSV. The diversity of the BRSVs found in this study needs be considered in vaccination strategies.

Bovine Respiratory Syncytial Virus (BRSV) Infection Detected in Exhaled Breath Condensate of Dairy Calves by Near-Infrared Aquaphotomics

Bovine respiratory syncytial virus (BRSV) is a major contributor to respiratory disease in cattle worldwide. Traditionally, BRSV infection is detected based on non-specific clinical signs, followed by reverse transcriptase-polymerase chain reaction (RT-PCR), the results of which can take days to obtain. Near-infrared aquaphotomics evaluation based on biochemical information from biofluids has the potential to support the rapid identification of BRSV infection in the field. This study evaluated NIR spectra (n = 240) of exhaled breath condensate (EBC) from dairy calves (n = 5) undergoing a controlled infection with BRSV. Changes in the organization of the aqueous phase of EBC during the baseline (pre-infection) and infected (post-infection and clinically abnormal) stages were found in the WAMACS (water matrix coordinates) C1, C5, C9, and C11, likely associated with volatile and non-volatile compounds in EBC. The discrimination of these chemical profiles by PCA-LDA models differentiated samples collected during the baseline and infected stages with an accuracy, sensitivity, and specificity >93% in both the calibration and validation. Thus, biochemical changes occurring during BRSV infection can be detected and evaluated with NIR-aquaphotomics in EBC. These findings form the foundation for developing an innovative, non-invasive, and in-field diagnostic tool to identify BRSV infection in cattle.