Comparison of four RT-PCR assays for detection of bovine respiratory syncytial virus

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.

Meta-Analysis of qPCR for Bovine Respiratory Disease Based on MIQE Guidelines

Qualitative and quantitative PCR-based tests are widely used in both diagnostics and research to assess the prevalence of disease-causing pathogens in veterinary medicine. The efficacy of these tests, usually measured in terms of sensitivity and specificity, is critical in confirming or excluding a clinical diagnosis. We undertook a meta-analysis to assess the inherent value of published PCR diagnostic approaches used to confirm and quantify bacteria and viruses associated with bovine respiratory disease (BRD) in cattle. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A thorough search of nine electronic databases (Web of Science, EBSCOhost, Cambridge journals online, ProQuest, PubMed, Sage journals online, ScienceDirect, Wiley online library and MEDLINE) was undertaken to find studies that had reported on the use of PCR and/or qPCR for the detection and/or quantification of BRD associated organisms. All studies meeting the inclusion criteria for reporting quantitative PCR for identification of BRD associated microorganisms were included in the analysis. Studies were then assessed on the applications of the Minimum Information for Publication of Quantitative Real-Time PCR Experiment (MIQE) and PCR primer/probe sequences were extracted and tested for in silico specificity using a high level of stringency. Fourteen full-text articles were included in this study. Of these, 79% of the analysed articles did not report the application of the MIQE guidelines in their study. High stringency in silico testing of 144 previously published PCR primer/probe sequences found many to have questionable specificity. This review identified a high occurrence of primer/probe sequences with a variable in silico specificity such that this may have implications for the accuracy of reporting. Although this analysis was only applied to one specific disease state, identification of animals suspected to be suffering from bovine respiratory disease, there appears to be more broadly a need for veterinary diagnostic studies to adopt international best practice for reporting of quantitative PCR diagnostic data to be both accurate and comparable between studies and methodologies.

Use of different cell lines for in vitro cultures of bovine respiratory syncytial virus

This study compared the use of different cell lines for in vitro cultures of bovine respiratory syncytial virus (BRSV). The BRSV 375 strain and 3 nasal swabs obtained from Simmental calves were used for this study. The culture was performed on 3 cell lines: bovine kidney cells (LLC-PK1), bovine tracheal cells (TBTR) and primary chicken embryo-related cells (CER). A comparative analysis of titres was performed using a microplate agglutination test with human group O erythrocytes and bovine erythrocytes. The presence of BRSV in all cell lines was confirmed using the reverse transcriptase polymerase chain reaction (RT-PCR) method. The first small refractile changes in the LLC-PK1 cells occurred at 48h after infection. Syncytial changes were noted 4 days after incubation. Large refractile cell changes were observed on day 3 of growth in the TBTR culture. Syncytia were observed on the second day after infection in subsequent passages. The cytopathic effect in the CER cells occurred 24h after infection, and syncytia appeared after 3 passages. Changes in syncytia indicate an adaptation of the virus for the infection of cells other than tracheal cells in primary and secondary cultures. The highest viral titre was obtained using the TBTR line. The titres obtained in the LLC-PK1 and CER cultures averaged 10(1.86)/ml. The low virus titres in all culture types suggest the need for research aimed at the optimisation of culture conditions.

Rapid Detection of Bovine Respiratory Syncytial Virus in Poland Using a Human Patient-Side Diagnostic Assay

Bovine respiratory syncytial virus (BRSV) plays a significant role in the etiopathogenesis of the respiratory syndrome in young cattle during their first year of life. Development of rapid and accurate BRSV diagnostic tools would aid in the appropriate control of this important pathogen. The objective of this study was to characterize infections induced by BRSV by means of rapid patient-side immunomigration assays used for diagnosis of human respiratory syncytial virus (hRSV) in humans. Nasal and tracheal swabs were obtained from healthy calves of various beef and dairy breeds - Holstein-Friesian, Simmental, Charolais, Belgian Blue and Limousin, between the ages of 5 and 12 months, from 26 farms. BRSV was identified using two rapid immunomigration assays, TruRSV® and Clearview® RSV, and compared with RT-PCR as a reference technique. BRSV was found in 73.1% of all the herds tested. High agreement with RT-PCR was obtained for TruRSV® (κ = 0.824), while in the case of the Clearview® RSV test, agreement with PCR was moderate (κ = 0.420). The results demonstrate that rapid patient-side immunomigration assays designed to detect hRSV can be used to accurately detect BRSV in field samples collected from cattle.

Use of rapid human respiratory syncytial virus strip tests for detection of bovine respiratory syncytial virus in experimentally vaccinated calves

Three different rapid strip tests: TRU RSV, BinaxNOW RSV and RSV Respi-strip were compared with RT-PCR and ELISA BRSV Ag for the ability to detect bovine respiratory syncytial virus (BRSV) in nasal swabs collected from calves experimentally vaccinated with live vaccine Rispoval RS-PI3. The reference strains of BRSV (375 and A51908) were detected by ELISA BRSV Ag whereas the strains of human respiratory syncytial virus (HRSV) and bovine parainfluenza virus type 3 (BPIV-3) were not. All rapid strip tests as well as RT-PCR reacted positively both to HRSV and BRSV reference strains and negatively to BPIV-3. The detection limit for RT-PCR was 39.1 TCID50 (strain 375 of BRSV), whereas for each of the rapid tests it was approximately 156 TCID50 and 312 TCID50 for antigen ELISA. Diagnostic sensitivity in detecting BRSV in nasal swabs for TRU RSV and RSV Respi-strip tests was 33% and 50% for BinaxNOW RSV. Diagnostic specificity of TRU RSV was 100%, whereas for both BinaxNOW and Respi-strip it was 87%. We concluded that TRU RSV could be used as a supportive rapid test for BRSV screening in nasal swabs taken directly on a farm. However, due to the small group of animals used in the experiment, the results should be regarded as preliminary and the study should be repeated on a larger number of animals.