Molecular diagnosis of bovine respiratory viruses in clinical and necropsy samples


Thesis Type: Doctorate

Institution Of The Thesis: Bursa Uludağ University, Turkey

Approval Date: 2019

Thesis Language: Turkish

Student: EDA BALDAN TOKER

Supervisor: Kadir Yeşilbağ

Abstract:

The aim of this PhD thesis is to determine the presence of bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus type 3 (BPIV-3), bovine viral diarrhea virus (BVDV) and bovine herpesvirus type 1 (BoHV-1), which are important viral pathogens of bovine respiratory disease. For that purpose, conventional virologic methods and molecular methods were employed. A total of 193 samples (133 nasal swabs and 60 lung tissue samples) from the cattle showing respiratory system findings were examined in Bursa and neighboring provinces. For virus isolation, all the samples were inoculated onto MDBK cell culture for 3 blind passages. In addition, the samples were tested by nested RT-PCR for BRSV; hemadsorption test and RT-PCR for BPIV-3; immunoperoxidase monolayer assay, antigen-ELISA and RT-PCR for BVDV; antigen-ELISA and PCR methods for BoHV-1. During virus isolation, 1 BPIV-3 (ET-81) and 2 non-cytopathogenic BVDV (DO-48 and ET-94) isolates were obtained. By antigen-ELISA tests, 10 samples were found to be positive for BVDV antigen, while there was no positive sample for BoHV-1 antigens. By RT-PCR and PCR, the prevalence of BRSV, BPIV-3, BVDV and BoHV-1 was determined as 2,59% (5/193); 0,52% (1/193); 2,59% (5/193) and 1,04% (2/193), respectively. 6,74% (13/193) of the animals tested were found to have respiratory infection caused by these viruses. Sequence analysis was performed on PCR products from selected samples. According to phylogenetic analyses, DO-7, ET-63 and ET-124 sequences were closely related to each other according to the F gene region of BRSV. ET-81 was found in the genotype of BPIV-3c according to HN protein gene region. DO-48, ET-64 and ET-94 sequences that were identified as BVDV-1 and 5′UTR-based analysis demonstrated the existence of BVDV-1f, BVDV-1a, and BVDV-1l subgenotypes, respectively. ET-121 sequence was found to take part in BoHV-1.1 subgroup according to gC gene region. No multiple infections could able to be detected in the samples.