Journal of Veterinary Science最新文献

Importance: Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus that threatens the pig industry and acts as a viral spillover, infecting other farm animals and potentially humans. The recent emergence of highly pathogenic PDCoV in South Korea, causing severe neonatal piglet mortality, underscores the urgent need for effective countermeasures to mitigate economic and public health risks. Thus, discovering new therapeutic methods through drug repurposing is crucial for controlling PDCoV.

Objective: This study investigated ivermectin (IVM) for its antiviral effect on PDCoV in vitro and explored its mechanism of action.

Methods: The antiviral effects and mechanism of action of IVM against PDCoV were evaluated using various virological assays.

Results: IVM markedly impaired the replication of PDCoV in a dose-dependent manner. Time-of-addition assays showed that the anti-PDCoV activity of IVM was most potent when administered before infection, simultaneously with infection, or immediately after infection. Further mode of action experiments revealed that IVM targeted the replication stage of PDCoV infection at post-entry steps.

Conclusions and relevance: Our results indicated that IVM interfered with PDCoV genome replication by impairing viral RNA synthesis. These findings suggest the potential of IVM for inhibiting PDCoV RNA polymerase and provide an invaluable therapeutic strategy to combat PDCoV infection with IVM, offering a viable alternative in the absence of commercial vaccines.

Importance: Leishmaniasis, caused by Leishmania parasites, is a significant global health issue with limited treatment options. Mitogen-activated protein kinase 3 (MAPK3) plays a crucial role in parasite survival and immune evasion, making it a promising therapeutic target. Nevertheless, existing treatments have substantial side effects, and no specific MAPK3 inhibitors are available.

Objective: This study evaluated the potential MAPK3 inhibitors capable of targeting L. donovani and L. martiniquensis using computational and experimental approaches.

Methods: Five compounds from the NCI database were screened using an ADP-Glo Kinase Assay for MAPK3 inhibition. Half-maximal inhibitory concentration (IC₅₀) analysis was performed to determine their potency. Molecular docking and molecular dynamics simulations were conducted to assess the binding interactions and stability. Cell-based assays were performed to evaluate the efficacy of these compounds against L. donovani and L. martiniquensis in the promastigote and amastigote stages.

Results: NSC107522, NSC196515, and NSC84100 inhibited MAPK3, with IC₅₀ values of 2.69 µM, 4.96 µM, and 10.59 µM, respectively. NSC107522 showed the strongest binding affinity (ΔG_bind = -111.20 kJ/mol) and reduced L. donovani survival in the promastigote (IC₅₀ = 2.68 µM) and amastigote (IC₅₀ = 4.04 µM) stages. NSC84100 exhibited superior activity against L. martiniquensis, with IC₅₀ values of 3.14 µM (promastigotes) and 2.61 µM (amastigotes).

Conclusions and relevance: NSC107522 and NSC84100 are promising MAPK3 inhibitors with species-specific activity. NSC107522 targets L. donovani, while NSC84100 is more effective against L. martiniquensis. These findings provide a foundation for developing targeted therapies against leishmaniasis, but further studies will be needed to determine their in vivo efficacy and optimize MAPK3-targeted drug design.

Importance: In-utero transmission of Johne's disease (JD), a chronic enteric condition caused by Mycobacterium avium subspecies paratuberculosis (MAP), has been reported. However, no study to date has confirmed in-utero transmission of MAP to fetuses in clinically infected Korean black goats.

Objective: To provide evidence of in-utero transmission in two clinically JD-infected pregnant goats and their fetuses through polymerase chain reaction (PCR) detection, bacterial isolation, and molecular epidemiological characterization.

Methods: Two pregnant goats were diagnosed with JD through clinical assessment, enzyme-linked immunosorbent assay, PCR detection, and bacterial culture. MAP isolates were genotyped using IS1311 PCR-restriction enzyme analysis and the mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) method.

Results: ISMav02 gene was detected in the jejunum, mesenteric lymph nodes (MLN), and placentomes of both goats. In addition, positive bands were observed in the cecum and colon tissues from Goat #2. All fetal intestine samples from both goats were positive, while the umbilical cords were positive in one fetus from each goat. Two MAP isolates were obtained: one from the placentome (Goat #1) and the other from the MLNs (Goat #2). Genotyping revealed two distinct cattle-type strains, including INRA Nouzilly MIRU-VNTR (INMV) 248 (novel type) and INMV 13.

Conclusions and relevance: This study provides the first direct evidence of in-utero MAP infection in clinically JD-infected pregnant goats in the Republic of Korea. Two distinct MIRU-VNTR genotypes were identified, including a novel MAP strain, highlighting the need for improved management strategies to prevent vertical transmission of JD and address genetic diversity within goat herds.

Importance: Embryo implantation is a hormone-regulated event requiring a receptive endometrium. In vitro models that simulate this process are essential for studying early embryonic development. Endometrial epithelial organoids (EEOs) provide a promising platform to model these interactions.

Objective: This study aimed to verify the response of porcine EEOs to steroid hormones and assess how steroid hormones affect embryonic attachment in a culture medium containing EEOs.

Methods: During a 7-day organoid in vitro culture mimicking the in vivo environment, estradiol (E₂) was administered from day 3, followed by progesterone (P₄) treatment on day 5. On day 7, porcine EEOs were harvested using a cell recovery solution. We compared the untreated control group with the hormone-treated groups and measured the expression levels of E₂ and P₄ receptors.

Results: The results demonstrated a higher receptor expression level in the hormone-treated groups than that in the control group. Additionally, the expression levels of genes associated with E₂ (fibroblast growth factor 7 and insulin-like growth factor 1) and P₄ (transforming growth factor β1) were higher in the hormone-treated group as compared to those in the control group. The efficiency of embryonic attachment was assessed through co-culture with EEOs harvested from both groups on the 7^th day and parthenogenetic embryos.

Conclusion and relevance: This study confirmed that porcine endometrial organoids respond to steroid hormones and support embryo attachment. These findings provide a translational basis for developing in vitro models to study implantation failure and infertility in reproductive medicine.

Importance: Streptococcus suis is a zoonotic pathogen that poses a threat to human and animal health. In pigs, it causes arthritis, meningitis, and septicemia, while in humans it leads to meningitis, endocarditis, pneumonia, septicemia, and septic shock. Effective control of this pathogen is important for both public and animal health.

Objective: This study characterized S. suis isolates from swine lesions in the Republic of Korea to provide insights into their epidemiological features.

Methods: Seventy-four isolates were collected from diverse tissues. Serotypes were determined using multiplex PCR targeting capsular polysaccharide genes, and multi-locus sequence typing (MLST) was conducted with seven housekeeping genes. The virulence-associated genes epf, mrp, and sly were screened by multiplex PCR.

Results: Sixteen serotypes were identified, with serotype 2 most prevalent (27.0%), followed by serotypes 3, 8, 7, 13, and 4. MLST revealed 41 sequence types, including 26 novel STs. Among virulence genes, sly was most frequently detected, but nearly half of the isolates were negative for all three genes. The serotype and sequence type distribution also showed notable year-to-year variations, indicating ongoing genetic diversification in Korea.

Conclusions and relevance: These findings underscore the need for continuous surveillance to track serotype shifts and the emergence of novel lineages. Molecular tools such as MLST and virulence gene profiling enhance epidemiological understanding and support risk assessment for this zoonotic bacterium.

Importance: Avian influenza virus (AIV) has emerged as a serious threat worldwide. In poultry, AIV can be divided into highly pathogenic AIV (HPAIV) and low pathogenic AIV (LPAIV). Exosomes are small vesicles released from donor cells that transmit cargo such as microRNAs (miRNAs), where exosomal miRNA can regulate target gene expression.

Objective: By profiling exosomal miRNAs from chickens infected with HPAIV and LPAIV, we provide insights into the immunological functions of exosomal miRNAs in AIV infection as well as into the development of strategies for its control.

Methods: This study analyzed the exosomal miRNA expression profiles of non-infected, LPAIV-infected, and HPAIV-infected chickens using small RNA sequencing. miRDB and Gene Ontology (GO) were used to predict immune-related target genes, and GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. Reverse transcription quantitative polymerase chain reaction was conducted to validate the expression levels of miRNAs (gga-miR-1434, gga-miR-1662, gga-miR-1559-5p, and gga-miR-375).

Results: We identified 148 DE miRNAs in total: 103 in LPAIV-EXO vs. CTRL-EXO, 54 in HPAIV-EXO vs. CTRL-EXO, and 98 in HPAIV-EXO vs. LPAIV-EXO, with partial overlap among groups. In the GO and KEGG analyses, the mitogen-activated protein kinase signaling pathway was the most enriched pathway in all comparisons.

Conclusions and relevance: This report provides insight into the molecular mechanisms by which exosomal miRNAs are related to immune-related pathways in HPAIV and LPAIV infections and is expected to be helpful for novel vaccine development and useful biomarkers for virus infections.

Importance: Vector-borne hemoparasitic diseases, such as Theileria, Babesia, Trypanosoma, Leishmania, and Anaplasma, pose significant constraints to livestock production, particularly in Africa and other tropical regions. These infections cause considerable economic losses from mortality, decreased productivity, and the high costs of treatment and control efforts.

Observations: Resistance to hemoparasitic infections in livestock is strongly influenced by the genetic factors of the host. The key host genes involved in immune responses (e.g., BoLA-DRB3 and TLR4), oxidative stress defense (SOD2 and GPX1), drug metabolism (ABCB1 and CYP3A4), and ectoparasite resistance (MC1R and MHC) have been identified as contributors to resistance phenotypes. On the parasite side, the genes responsible for immune evasion (VSG and AP2), drug resistance (MDR1 and CYTB), and host cell invasion (AMA1 and HSP90) play pivotal roles in infection persistence and treatment failure. The advances in genomic and transcriptomic tools, including genome-wide association studies, CRISPR, and multi-omics profiling, have enhanced the understanding of these host-parasite interactions and enabled identification of the molecular markers for resistance traits.

Conclusions and relevance: Advanced genetic resistance offers a sustainable, long-term solution to managing vector-borne parasitic infections in livestock. The integration of resistance-associated markers into selective breeding programs, coupled with genome editing and real-time surveillance, can improve livestock resilience. Aligning these efforts with One Health strategies and collaborative genomic initiatives will be essential for achieving effective, regionally adapted disease control.

Importance: Glutathione S-transferases (GSTs) are detoxifying enzymes that protect cells from xenobiotics. In mouse kidneys, class α GST (GSTA) isoforms display sexually dimorphic expression, with males exhibiting lower levels.

Objective: This study investigates the effect of testosterone on renal GSTA isoform expression in male mice.

Methods: Renal expression of GSTA1/2, GSTA3, and GSTA4 was examined in orchiectomized mice with or without testosterone supplementation, as well as in intact mice treated with antiandrogens including bicalutamide and flutamide or exhibiting either high (HT) or low (LT) serum testosterone levels.

Results: Orchiectomy increased the expression of GSTA1/2, GSTA3, and GSTA4 at both the mRNA and protein levels, accompanied by elevated enzyme activity measured using cumene hydroperoxide (CHP), a GSTA-specific substrate. Testosterone supplementation reversed these effects. Treatment with antiandrogens upregulated renal GSTA isoform expression in male mice, suggesting that GSTA isoform regulation is mediated through androgen receptor signaling. In male mice, GSTA1/2 expression was significantly lower in the HT group than in the LT group, while GSTA3 and GSTA4 expression remained relatively unchanged. Consistently, renal GST activity toward CHP was also lower in HT mice.

Conclusions and relevance: These suggest that testosterone suppresses renal GSTA isoform expression in male mice, with GSTA1/2 being more sensitive to testosterone-mediated inhibition than GSTA3 or GSTA4.

Importance: Avian influenza virus (AIV) is classified into subtypes by hemagglutinin (HA) and neuraminidase (NA) genes. Wild waterfowl harbor H1-H16 and N1-N9 subtypes. Large-scale AIV surveillance requires substantial labor, time, and cost when using conventional HA and NA subtyping methods.

Objective: This study aimed to develop multiplex reverse transcription polymerase chain reaction (RT-PCR) and universal assays to detect all H1-H15 and N1-N9 subtypes in just eight RT-PCR reactions.

Methods: Subtype-specific forward primers and conserved reverse primers were used to identify HA and NA subtypes based on RT-PCR amplicon size. The HA cleavage site was characterized by sequencing. For NA, a universal forward primer enabled sequencing-based subtyping from a single reaction with the universal reverse primer.

Results: Seventy reference strains and 113 low pathogenic AIVs (from 2021-2022 and 2022-2023 season), covering H1-H15 and N1-N9 subtypes, were tested. The performance of this method was nearly complete, with a few subtype/cleavage site exceptions in relatively long-stored samples. The assays showed 98.90% sensitivity for HA (181/183), 98.91% for NA (182/184), and 100% specificity for both of HA and NA subtyping.

Conclusions and relevance: These subtyping assays offer a rapid, sensitive, and cost-effective method for AIV subtyping, enhancing efficiency in large-scale surveillance.

Importance: African Swine Fever (ASF) is a highly contagious and fatal disease severely affecting Romania's pig industry and wild boar populations. This study provides insights into the prevalence of ASF in Constanța County, where wetlands like the Danube Delta and Danube River, home to dense wild boar populations, facilitate the spread of the virus to domestic pigs.

Objective: The study examined the incidence of ASF in pig and wild boar populations over six years (2018-2023) in Constanța County, Romania's second outbreak origin in 2018.

Methods: The real-time polymerase chain reaction data from 3,187 samples (2,204 pigs and 983 wild boars) collected between 2018 and 2023 were analyzed. A 251 bp fragment of the African Swine Fever virus (ASFV) B646L gene (positions 105,320-105,570; GenBank MN194591.1), encoding the capsid protein p72, was amplified using a TaqMan assay, sequenced in 10 ASFV-positive samples, and subjected to phylogenetic analysis against ASFV GenBank references.

Results: Analysis revealed a decline in ASF outbreaks in Constanța County, from 93 in 2018 to only two in 2022. Despite this, 2023 saw a resurgence, with 38 cases and 21 outbreaks in pigs from nearby private households, likely due to poor biosecurity. Phylogenetic analysis of 10 ASFV isolates and GenBank sequences from Europe, Asia, and Africa confirmed 100% similarity to strain II. ELISA testing identified ASFV antibodies in 23 of 144 pigs (15.9%) and 28 of 559 wild boars (5.0%), indicating that some animals survived ASFV infection.

Conclusions and relevance: The results revealed a steady decline in ASF outbreaks and cases in Constanța County, attributed to eradication measures. The detection of ASFV antibodies in 51 animals highlights post-infection survival in both domestic pigs and wild boars, offering valuable insight for future research on the genetic basis of acquired immunity.