A LATENT VIRAL AGENT IN DAIRY FARMS: MOLECULAR CHARACTERIZATION OF BOVINE HERPESVIRUS 4 IN TÜRKİYE

Background and Objective: The livestock industry plays a crucial role in serving global demand for

animal protein. Early detection and monitoring of cattle diseases (Herpesviral infections ie.), as well as

sustainable health policies, contribute to minimizing economic losses. Bovine Herpesvirus-4 (BHV-4) is

a significant viral pathogen associated with genital and respiratory system infections in cattle, and its

potential for latent infection, often presenting as subclinical, poses a considerable risk within the herd.

Because of this silent circulation, it may pose a risk to economically sustainable cattle farming. The aim

of this study was to determine the presence of BHV-4 in Erzurum Province using molecular methods

and to identify the strains through phylogenetic analysis.

Materials and Methods: In this study, samples were taken from four family cattle farms located in the

Eastern Anatolia Region of Türkiye. A total of 40 blood samples were collected from cows, and the

clinical conditions were recorded. Viral nucleic acid was extracted from blood samples. Conventional

PCR analysis was performed using primers specific to the BHV-4 glycoprotein B (gB) gene region. The

amplicons identified as positive were sequenced. The sequence data obtained were compared with

BHV-4 reference sequences registered in GenBank to perform a phylogenetic analysis.

Results: Based on the PCR analysis, 4 of the 40 cows in the study (10%) tested positive for the BHV-4

gB gene. The one of the positive animals had a history of abortion, while another exhibited enlarged

retropharyngeal and prescapular lymph nodes. No specific clinical findings were observed in the other

two positive animals. Sequence analysis revealed that Genotype II (n=3) and Genotype III (n=1) strains

were circulating in the Eastern Anatolia region. Phylogenetic analysis revealed that strains from this

study shared close genetic relationships with previously reported BHV-4 strains from Türkiye, Germany,

Iran, USA and, Argentina.

Conclusions: This study has showed that BHV-4 can circulate asymptomatically in herds and may also

play a role in certain clinical cases. While previous studies in Türkiye have reported the presence of

three BHV-4 genotypes, Genotype I is indicated as the predominant genotype. In this study, Genotype

II and Genotype III strains were detected in the eastern region of Türkiye. The presence of frequent

animal movements, shared grazing land, and widespread animal trade in this region may facilitate the

spread of BHV-4 between regions. These findings highlight the importance of molecular-level

monitoring and strain typing of BHV-4 in cattle herds both in regional and worldwide.