Sessions

In this study, blood samples were collected from 29 cattle farms to map the BVDV-1 virus subtypes and biotypes present in Hungary. This information will be utilized for future vaccine efficacy studies. We processed over 100 samples weekly, and throughout the course of our research, we obtained 326 BVDV-positive RT-PCR results. Samples that reached a cycle threshold (Ct) value of ≤ 25 in the PCR assays were selected for Sanger sequencing. Among the 87 sequenced viral genomes, 60 belonged to the BVDV-1f subtype, 14 to 1b, and 13 to 1d. According to our survey, subtype 1f is predominant in Hungary.

The persistence, spread, and mutation of the virus on farms—as well as the economic loss caused by BVDV—are primarily driven by persistently infected animals. Therefore, the detection of these animals is a key element in every eradication protocol. Therefore, in this study it is well emphasized. Out of the 326 samples, 133 were additionally tested using ELISA, which yielded 47 positive, 83 negative, and 3 ambiguous results. In total, we identified 83 persistently infected animals.

Virus propagation kinetic studies were conducted using two 1f (cytopathic), two 1b (non-cytopathic and cytopathic), and one 1d subtype viral strains.

We also performed complete genome metagenomic analyses on these five viral strains, seeking molecular differences among the various biotypes and subtypes. Our study highlights the importance of the continuous monitoring of BVDV subtypes circulating in the country, as it is crucial to ensure that the currently available vaccines provide effective protection against all variants.