Latitude and seasons influence the prevalence of Theileria orientalis and affect the hematology of non-grazed dairy cows in Korea.

This pilot study aimed to investigate the effects of regional and seasonal variations on the prevalence of Theileria orientalis and the hematological profile of non-grazed dairy cows in Korea. A total of 365 clinically healthy lactating Holstein Friesian cows from 26 dairy farms in 7 provinces that were categorized into northern, central, and southern regions were sampled during the warm period from July to August and the cold period from October to December. The detection of T. orientalis major piroplasm surface protein gene and the hematology non-grazed dairy cows were analyzed using peripheral blood samples. The T. orientalis prevalence was 20.0% (73/365). The prevalence in the southern region was 35.9%, which was significantly higher than that in the central (21.6%) and northern (12.9%) regions (P < 0.05). The prevalence during warm period was higher (43.0%) than that during the cold season (13.5%). The infected cows showed significantly lower erythrocyte counts in the southern region (5.8 ± 0.6 M/µl) and during the warm period (5.8 ± 0.7 M/µl) compared with those in the central and northern regions and during the cold season, which affected the extended RBC parameters, including hematocrit and hemoglobin concentrations. Our findings revealed the prevalence of T. orientalis in Korea, highlighting its high occurrence during warm periods and in certain geographical regions. Climatic factors could contribute to the health and productivity of cattle, as evidenced by the prevalence of T. orientalis and its negative impact on animals.

Pilot study on the distribution of caseous lymphadenitis in Korean native goats and the relationship between sex and age in disease occurrence.

Caseous lymphadenitis (CLA) caused by Corynebacterium pseudotuberculosis is a chronic disease that affects goats. The Korean native goat (KNG) is the most popular goat breed raised in Korea. In this study, the distribution of CLA in the KNG population and the relevance of sex and age in disease development were determined. From March 2020 to February 2021, 1,177 KNGs from 110 farms were assessed. The distribution of CLA in animals was determined by a veterinary inspector who performed gross examinations of goat carcasses and confirmed diagnoses via polymerase chain reaction and bacteriological examination. The CLA detection rate in the KNG population was 19.80%, and more than half of the farms were affected by the disease (56.36%). A statistically significant difference was observed among the sex groups, with castrated males (13.98%) having the lowest detection rate, followed by intact males (22.48%) and females (24.09%), suggesting that castration has a positive effect on reducing the risk of CLA (p < 0.05). In terms of age groups, an increased detection rate of 28.16% was observed in the late adult (>2 years) group. Phylogenetic analysis indicated that the RNA polymerase beta subunit-encoding gene can effectively differentiate biovar ovis from biovar equi and can be used for further epidemiological studies of C. pseudotuberculosis. This is the first nationwide surveillance study of CLA distribution to confirm the continuous occurrence of CLA in Korean goat farms. Future studies should include risk factor analyses of CLA based on herd levels to prevent and control this disease in Korea.

Microbiome Shift, Diversity, and Overabundance of Opportunistic Pathogens in Bovine Digital Dermatitis Revealed by 16S rRNA Amplicon Sequencing.

This study analyzed the diversity and phylogenetic relationship of the microbiome of bovine digital dermatitis (BDD) lesions and normal skin from cattle foot by using 16S rRNA amplicon sequencing. Three BDD samples and a normal skin sample were pre-assessed for analysis. The Illumina Miseq platform was used for sequencing and sequences were assembled and were categorized to operational taxonomic units (OTUs) based on similarity, then the core microbiome was visualized. The phylogeny was inferred using MEGA7 (Molecular evolutionary genetics analysis version 7.0). A total of 129 and 185 OTUs were uniquely observed in normal and in BDD samples, respectively. Of the 47 shared OTUs, 15 species presented increased abundance in BDD. In BDD and normal samples, Spirochetes and Proteobacteria showed the most abundant phyla, respectively, suggesting the close association of observed species in each sample group. The phylogeny revealed the evolutionary relationship of OTUs and the Euclidean distance suggested a high sequence divergence between OTUs. We concluded that a shift in the microbiome leads to richer diversity in BDD lesions, and the overabundance of opportunistic pathogens and its synergistic relationship with commensal bacteria could serve as factors in disease development. The influence of these factors should be thoroughly investigated in future studies to provide deeper insights on the pathogenesis of BDD.

Genotypic and Phenotypic Characterization of Treponema phagedenis from Bovine Digital Dermatitis.

This study aimed to isolate and characterize Treponema spp. from bovine digital dermatitis (BDD)-infected dairy cattle. Seven isolates were characterized in this study. Isolates exhibited slow growth, and colonies penetrated the agar and exhibited weak ß-hemolysis. Round bodies were observed in old and antibiotic-treated cultures. Cells ranged from 9-12 µm in length, 0.2-2.5 µm in width, and were moderately spiraled. The 16S rRNA analysis revealed the isolates as Treponema phagedenis with >99% sequence homology. Isolates had alkaline phosphatase, acid phosphatase, ß-galactosidase, N-acetyl-ß-glucosaminidase, esterase (C4), esterase lipase (C8), naphthol-AS-BI-phosphohydrolase, and ß-glucuronidase activities. Low concentrations of ampicillin, erythromycin, and tetracycline were required to inhibit the growth of isolates. Formic, acetic, and butyric acids were produced, while propionic acid was significantly utilized, indicating its essentiality for treponemal growth. The isolates shared the same characteristics and, therefore, were considered as a single strain. Isolate HNL4 was deposited as a representative isolate (Treponema phagedenis KS1). The average nucleotide identity of strain KS1 showed a small difference with the human strain (99.14%) compared with bovine strain (99.72%). This study was the first to isolate and characterize Treponema phagedenis from BDD in Korea and, hence, it delivered pathogenicity-related insights and provided valuable information that can be used for the management of BDD.

Treponema spp., the dominant pathogen in the lesion of bovine digital dermatitis and its characterization in dairy cattle.

This study examined the presence of Treponema in lesions using conventional PCR detection methods and investigated the microbiome by performing high-throughput DNA sequencing. Twenty-nine bovine digital dermatitis (BDD) lesions were collected from 25 dairy farms in South Korea that were tested by PCR amplification using sets of one universal, one genus-specific, and three species specific Treponema PCR primers. Three BDD samples were randomly selected and normal tissue samples were submitted for 16S rRNA sequencing using the Illumina MiSeq platform. The dominant phylum present in all tested BDD lesions was Spirochaetes with a mean relative abundance of 46.9 %, and Treponema was the most abundant genus. Spirochaetes abundance was followed by the phyla Tenericutes and Bacteroidetes with 14.1 % and 11.8 % mean abundances, respectively. Co-infecting bacteria from phyla Tenericutes and Bacteroidetes may be involved in the progression of BDD. Bovine digital dermatitis infection is polymicrobial in nature, but Treponema spp. are the main etiologic agents of the disease. In the microbiome results, Treponema pedis had the highest mean relative abundance (20.9 %) in the BDD lesions in this study followed by T. denticola, T. medium, T. lecithinolyricum, Spirochaeta africana, and Sediminispirochaeta bajacalifoniensis. All 29 samples were positive in the genus-specific Treponema PCR results. The species-specific PCR resulted in 75.9 %, 86.2 %, and 69.0 % of samples in groups T. medium/T. vincentii-like, T. phagedenis-like, and T. pedis, respectively. Understanding how these microorganisms mutually interact in the host during certain stages of infection may help in the development of better practices for controlling BDD.

High quality genome sequence of Treponema phagedenis KS1 isolated from bovine digital dermatitis.

Treponema phagedenis KS1, a fastidious anaerobe, was isolated from a bovine digital dermatitis (BDD)-infected dairy cattle in Chungnam, Korea. Initial data indicated that T. phagedenis KS1 exhibited putative virulent phenotypic characteristics. This study reports the whole genome assembly and annotation of T. phagedenis KS1 (KCTC14157BP) to assist in the identification of putative pathogenicity related factors. The whole genome of T. phagedenis KS1 was sequenced using PacBio RSII and Illumina HiSeqXTen platforms. The assembled T. phagedenis KS1 genome comprises 16 contigs with a total size of 3,769,422 bp and an overall guanine-cytosine (GC) content of 40.03%. Annotation revealed 3,460 protein-coding genes, as well as 49 transfer RNA- and 6 ribosomal RNA-coding genes. The results of this study provide insight into the pathogenicity of T. phagedenis KS1.