Veterinary Research Forum

Abstract Bovine respiratory disease (BRD) is a significant disease in the cattle industry worldwide. The interaction between environmental factors, hosts, livestock management, and viral and bacterial pathogens causes this disease. Viruses are crucial in the initiation and progression of BRD. This study was the first to investigate the prevalence of BRD viruses using the reverse transcription polymerase chain reaction method in nasal and eye conjunctival swabs and blood samples of 115 BRD calves in the central desert of Iran. At least one investigated virus was detected in 44 animals (38.26%). The detection rates of bovine viral diarrhea virus, bovine coronavirus, bovine adenovirus, bovine respiratory syncytial virus, bovine herpes virus-1, and bovine para influenza virus-3 were 20.00, 14.78, 5.21, 0.86, 0.00, and 0.00%, respectively. Three animals (2.60%) had a simultaneous infection with two viruses. Detection of bovine viral diarrhea virus, bovine coronavirus, and bovine adenovirus was correlated. The virus infection rates were 31.81 and 44.66% in five sampled cities. The virus detection rate in infected animals was related to the nose (26 animals; 50.09%), nose and eyes (seven animals; 15.90%), eyes (seven animals; 15.90%), nose, eyes, and blood (three animals; 6.81%), and blood (one animal; 2.27%) samples. The virus detection rate in different samples was in separate clusters. Monitoring and controlling the circulation of bovine viral diarrhea virus and bovine coronavirus in the central desert of Iran is vital due to the high detection rate. Our results highlight the necessity of investigating other viruses and bacterial agents related to the BRD in the study area.

Abstract Bovine ephemeral fever (BEF) is a debilitating disease of cattle and water buffaloes. Bovine ephemeral fever viruses (BEFVs) form four phylogenetic lineages including the Middle East, East of Asia, Australia and Africa, while the exotic viral strains have also been detected in different geographic areas. We characterized eight BEFVs from different regions of Iran during a period of seven years from 2015 to 2022. Sequencing the entire length of the G gene, the BEFVs were classified in the Middle Eastern lineage with the maximum of 99.73% and minimum of 97.30% nucleotide identity. The all Iranian and Turkish BEFVs detected during the large epizootic in 2020 were clustered phylogenetically together. However, no amino acid variation was observed between the Iranian viruses detected in 2020 and those identified before 2020 in the Middle Eastern lineage suggesting that host, environmental and other genetic factor (s) might have involved in occurrence of the epizootic in 2020. Two BEFVs detected during 2022 outbreak from Kermanshah and Narmashir in the west and east of Iran, respectively, were clustered in two distinct groups as a novel amino acid substitution H51Y in the epitope G3 was also identified in Kermanshah 2022 sequence. These results imply that the Middle Eastern lineage replaced the previously circulated East Asian BEFVs in Iran during 2012 to 2013 and also signify the emergence of new BEFVs due to the intra-lineage evolution. Continuous monitoring of the circulating viruses and identifying the potential vector (s) and its biology help better understand epizootiology of BEFV in the high-risk region.

Abstract Bovine viral diarrhea virus (BVDV) is an important viral agent causing reproductive failure in cattle. The objectives of the current study were to investigate the interaction between two BVDV biotypes, cytopathic (CP) and Non-cytopathic (NCP) and bovine gametes during in vitro fertilization (IVF) processing, the existence of the virus within embryonic cells and early embryonic development rates. Sperm and ova were exposed separately to CP and NCP BVDV at two concentrations of 10^4.5 and 10^5.5 tissue culture infectious dose 50.00% (TCID₅₀) mL^-1 prior to IVF, respectively. After five days post-IVF, early embryonic development rates of infected groups were assessed. Several embryos of each group, normal and degenerated, were selected for a viral assay using reverse transcription polymerase chain reaction technique. The result showed that the early embryonic development rates were decreased in treatment groups. The rates in the CP groups were lower than the NCP groups. In the CP groups, the proportions were, respectively, 10.00, 6.00 and 11.00, and 6.00% in the infected sperm and oocyte groups (10^4.5 and 10^5.5 TCID₅₀ mL^-1) that were higher than 50.00% in the control group. In NCP groups, the rates were, respectively, 25.00, 18.00 and 24.00, and 21.00% in the infected groups compared to 48.00% in the control group. In the CP groups, no BVDV was detected in normal embryos, whereas, all degenerated embryos were completely virus-positive. In the NCP groups, the virus was detected in both normal and degenerated embryos. In conclusion, this study supported detrimental impacts of CP and NCP BVDV on early embryonic development and the role of sperm and the zona pellucida layer as carriers of the virus. 

Abstract Bovine ephemeral fever is an acute and arthropod-borne viral disease of cattle and water buffalo which occurs seasonally in most of the world tropical and subtropical regions. The epizootic feature of the disease has been reported in Iran with serious economic consequences. The surface glycoprotein G of bovine ephemeral fever virus (BEFV) is composed of 4 antigenic sites (G1-G4) and plays the main role for eliciting neutralizing antibodies and protective immunity. The G1 – epitope is a linear antigenic site and conserved among BEFV strains. In order to develop an ELISA test based on G1-epitope as coating antigen, this study was carried out to express the recombinant G1-epitope of BEFV in prokaryotic system. Using PCR and specific primers, a length of 88 amino acid of the G glycoprotein of BEFV including G1- epitope was amplified and cloned into the expression vector pGEX-4T-1, with the GST moiety. The recombinant plasmid (pGEX-4T-1-G1) was then transformed into Escherichia coli BL₂₁ and expression of fusion protein was induced by 0.10 mM IPTG. The maximum expression of the fusion protein was obtained at 16 hr post induction as verified by SDS-PAGE electrophoresis, and it was also confirmed that this protein bearing G1- epitope is sufficiently biologically active to bind to anti-BEFV serum in western blot experiment.