Serological investigation of viruses that cause respiratory tract infections in cattle and sheep in the Central Black Sea region

In Türkiye, for many years, the Bovine Respiratory Disease Complex (BRD/BRDC) caused significant losses in farm animals' economies, placing a heavy burden on the national livestock industry. Because of this, many serological and virological studies have been conducted to define the viral etiological pathogens within this complex. Viruses like Bovine Herpes Virus Type 1 (BoHV-1), Bovine Viral Diarrhea Virus (BVDV), Bovine Respirovirus Type-3 (BPIV-3), Bovine Respiratory Syncytial Virus (BRSV), Bovine Adenovirus (BAV) and Bovine Corona Virus (BCoV) were believed to be the main causative agents of BRDC. However, most of the previous surveys of these viruses had been undertaken using international reference strains; thus, for obtaining more accurate results, we sought to use local strains of the three essential pathogens (BoHV-1, BRSV, and BPIV-3c) that causing this complex, which were detected, isolated, and molecularly characterized from lung autopsy of animals that died as a result of the BRDC infection recently in Northern Türkiye. In this study, we aimed to collect comprehensive data on the status of BRDC viruses and investigate their serological presence in Türkiye's central Black Sea region from the past to the present. To this end, 1750 archived serum samples (1000 cattle and 750 sheep) collected between the years 2018-2020 were employed for this doctoral project using field isolates detected and molecularly characterized from the same region by us. As a result of the neutralization tests, which was the followed serological method for our research to all 1750 serum tested samples, 143 BRSV, 182 BoHV-1, and 247 BPIV-3c antibody positive serum samples were detected, and the overall seropositivity rate for BRSV, BoHV-1, and BPIV-3c was assessed as (8.17%), (10.40%) and (14.11%), respectively. In conclusion, without regard to animal species, BPIV-3 was the most serologically detected local isolate in the cattle and sheep examined serum samples of our Central Black Sea region, while BRSV and BoHV-1 isolates were at certain levels of prevalence rates. Also, it has been determined that BPIV-3 infections have high seroprevalence values in different provinces of our country.