Journal of Veterinary Science最新文献

Importance: Porcine circovirus type 2 (PCV2) is a major pathogen responsible for the porcine circovirus-associated disease, causing significant economic losses in the swine industry worldwide. PCV2d has become the dominant, following a sequential shift from the previously predominant PCV2a and PCV2b genotypes. Although an effective vaccine based on virus-like particles (VLPs) of recombinant PCV2d-based capsid protein has been developed, intramuscular inoculation of the vaccine still induces a wide variety of side effects. In contrast, intradermal vaccination offers benefits, including enhanced immune activation due to the abundance of dendritic cells in the dermal layer, while also reducing side effects.

Objective: Developing a novel vaccine combined with a needle-free inoculation technique is required to elicit protection against PCV2d infection with fewer side effects and higher effectiveness. This study aimed to develop a VLP-based vaccine targeting PCV2d and assess its efficacy when administered intradermally using a needle-free system.

Methods: To optimize the intradermal vaccine formulation, we evaluated humoral immunity and neutralizing activity following intradermal administration of test vaccines prepared with varying adjuvant types, adjuvant ratios, and antigen doses.

Results: IMS1313 adjuvant provided the best induction of total IgG and neutralizing antibody titers. A dose-dependent evaluation indicated that 20 μg of antigen combined with 40% IMS1313 achieved optimal immune responses. Compared to intramuscular injection, intradermal injection using this formulation induced 1.3-fold higher neutralizing antibody titers, demonstrating higher efficacy.

Conclusions and relevance: Intradermal vaccination using a PCV2d VLP-based vaccine improves immunogenicity and cost-effectiveness, providing a promising strategy for controlling PCV2d infections in swine.

Importance: Research on tissue preservation, including cortical bone, skin, nerves, and vessels in glycerol and cortical bone in honey, has shown positive results. On the other hand, relatively few studies have been performed on fascia preservation, and comparisons between different fascia preservation methods remain scarce.

Objective: This in vitro study compared the biomechanical properties of five different methods of preserving fascia lata.

Methods: The control group underwent biomechanical testing immediately after decellularization, while the other five groups were stored in glycerol, honey, deep freezer, lyophilizer, and liquid nitrogen for 30 days. The ultimate load, elongation at failure, and stiffness for each group were determined from a load-elongation curve.

Results: A comparison of the ultimate load showed that the control group had the highest value, followed by the glycerol group. The glycerol group was the only group that did not show a significant difference from the control group, while all the other groups showed a significantly lower ultimate load. A comparison of elongation at failure revealed the glycerol group to have the highest value at failure among all groups and was significantly higher than the deep freeze, honey, and cryopreservation groups.

Conclusions and relevance: Glycerol can be used as an effective method for preserving fascia allografts because the resulting allografts show a similar ultimate load to the control group and the highest mean elongation at failure.

Importance: The Japanese encephalitis virus (JEV) is a massive threat to the pig-raising industry and attenuated-live vaccines are used widely to prevent JEV infections. Primary hamster kidney cells and Vero cells are mainly used to propagate JEV-attenuated vaccines.

Objective: This study aimed to construct porcine mesangial cells (PMCs) for JEV cultivation and study its characteristics.

Methods: An immunofluorescence assay was used to analyze the homogeneity of PMCs. Karyotypic analysis and flow cytometry were used to detect the cell chromosome numbers and cell cycle, respectively. TCID₅₀ was used to measure the viral titers.

Results: The prepared PMCs were uniform in shape and without variation in chromosome numbers. The PMCs exhibit strong division and proliferation ability, and the JEV could replicate efficiently, having a similar cytopathic effect to that in Vero cells. The viral titer results showed that the JEV grows faster in PMCs than in Vero cells.

Conclusions and relevance: This study generated an immortalized PMC cell line suitable for cultivating the JEV, which has significance for producing pig JEV-attenuated vaccines.

Importance: Pseudorabies (PR) is a significant disease that adversely affects the healthy growth of the pig industry in China. However, data on molecular epidemiology and genetic characterization of PRV is sparse.

Objective: This study examined the epidemic trends and variation characteristics of the PR virus (PRV) in Henan Province of China.

Methods: Six hundred eighty-eight clinically infected pig tissue samples were collected from 18 cities in Henan Province from January 2021 to March 2023 and tested for the PRV. The PRV was isolated from positive samples and identified by a polymerase chain reaction and immunofluorescence assay. The gB, gC, gD, and gE genes of the isolates were then amplified and sequenced for phylogenetic analysis. The gC and gE gene sequences of the isolates in this study were deduced to the respective amino acids for sequence analysis. Selected isolates were evaluated for pathogenicity in KM mice.

Results: The positive rate of PRV nucleic acid was 7.99% (55/688) in Henan Province, China. This study isolated eight PRV strains, all of which were genotype II variants. Seven isolates displayed unique amino acid mutations in the gC or gE proteins. The isolates of G22, HN4, QX, and QX2 can cause acute neurological symptoms in KM mice, with 50% lethal dose values of 10^4.2, 10^4.5, 10^5.2, and 10^4.8 50% tissue culture infectious doses, respectively.

Conclusions and relevance: This study revealed a high prevalence of the PRV in Henan Province, with genotype II variants being the predominant strains. These findings provide essential data for the prevention and control of the PRV.

Importance: Ticks transmit severe human and animal diseases, posing global health and economic risks. Haemaphysalis longicornis spreads infections like Rickettsia, Theileria, and Anaplasma, exacerbating concerns. Conventional tick control, including chemical acaricides, faces challenges like toxicity, non-target effects, and resistance. Innovative, sustainable strategies are essential. Advances in tick antigen research have identified molecular targets, paving the way for anti-tick vaccines as a promising, eco-friendly alternative to manage H. longicornis infestations and reduce tick-borne disease transmission. This review explores recent discoveries in tick antigens, the development of recombinant proteins, and their knockdown effects on H. longicornis infestations.

Observations: Several novel antigens target essential physiological processes for tick survival. Reproductive and developmental antigens, such as subolesin and subolesin+cystatin, regulate immunity and reproduction, reducing blood feeding, oviposition, egg mass, and hatching rates. Knockdown of recombinant P27/30 impairs embryogenesis, significantly reducing larval survival. Chitinase inhibition disrupts molting, impairing nymph development. Metabolic enzymes like enolase and GSK-3β regulate homeostasis and energy production; their inhibition reduces feeding efficiency and survivability. Additionally, ribosomal protein S27 and troponin I-like protein, essential for protein synthesis and muscle contraction, respectively, impact tick growth and mobility. These antigens may serve as valuable vaccine targets for controlling H. longicornis.

Conclusions and relevance: Anti-tick vaccines offer a cost-effective, sustainable alternative to chemical controls. Advances in transcriptomics, genomics, and proteomics have identified promising antigens, with subolesin, chitinase, troponin I-like protein, GSK-3β, and enolase demonstrating strong potential. Enolase, affecting immunity, reproduction, and pathogen transmission, emerges as the most effective target for reducing H. longicornis infestations.

Importance: Species of the genus Corynosoma are acanthocephalan parasites widely distributed among fish-eating mammals and birds. However, their occurrence in pinnipeds within Korean waters has been rarely documented. Previously, only a single case involving C. strumosum in a spotted seal has been reported. Clarifying the presence and distribution of Corynosoma in Korean waters is essential for improving regional parasite surveillance and assessing related ecological and zoonotic risks.

Objective: The northern fur seal (Callorhinus ursinus) inhabits the North Pacific and occasionally reaches Korean waters during its nonbreeding season. Despite this migratory presence, no acanthocephalan infections have been reported in this host in Korea. This study sought to fill that gap by examining a bycaught northern fur seal for intestinal parasites and characterizing the recovered acanthocephalans.

Methods: In 2013, a dead northern fur seal was recovered off Goseong-gun, East Sea, Korea. Acanthocephalans collected from the small intestine were examined using light microscopy, histology, and scanning electron microscopy. Morphological features were compared with existing descriptions.

Results: Twenty-two specimens (3 males, 19 females) were identified as Corynosoma spp., exhibiting sexual dimorphism and typical proboscis hook arrangements (16-20 rows, 8-11 hooks/row). Genital spines were present only in males. Morphological similarities with C. strumosum, C. simile, and C. magdaleni were noted, but species-level identification was inconclusive due to overlapping traits and lack of genetic data.

Conclusions and relevance: This first report of Corynosoma from a northern fur seal in Korea expands the known host and geographic range of the genus. The findings highlight the need for further morphological and molecular studies to better understand parasite diversity and potential zoonotic risks in Korean marine ecosystems.

Importance: Reports comparing the pharmacokinetics of ampicillin (AMP) and its prodrug bacampicillin (BAC) in poultry are scarce.

Objective: This study evaluated the pharmacokinetic characteristics of AMP and BAC in chickens and turkeys after intravenous (i.v.) or oral administrations at a single dosage of 25 mg/kg body weight.

Methods: Thirty chickens and 30 turkeys were divided into three groups (n = 10). Blood samples (0.5-0.7 mL) were collected from the subcutenea ulnar vein at pre-assigned times up to 12 h. The AMP and BAC plasma concentrations were analyzed using high-performance liquid chromatography with a fluorescence detector. The data were analyzed using noncompartmental methods.

Results: The area under the curve from 0 to 12 h, apparent total systemic, the apparent volume of distribution, and mean residence time differed significantly according to the administration routes. The terminal elimination half-life values for the i.v. AMP, oral AMP, and oral BAC routes were 1.81, 3.64, and 5.39 h (p = 0.0249, p < 0.05), respectively, in chickens, and 2.44, 2.53, and 5.5 h (p < 0.0001), respectively, in turkeys. The bioavailability for the oral AMP and oral BAC groups in chickens was 25.9% and 44.6%, respectively. Similarly, in turkeys, the bioavailability was 19.1% and 44.2% for the oral AMP and oral BAC groups, respectively.

Conclusions and relevance: The oral route of BAC with good bioavailability can be preferred for treating various conditions. On the other hand, further studies will be needed to determine the clinical efficacy of BAC during bacterial infections and the pharmacokinetics and safety of repeated administration in poultry.

Importance: Previous reports on thelaziasis from the Republic of Korea focused on parasite identification and zoonotic infections in humans. This retrospective study aimed to characterize the clinical patterns of thelaziasis in pet dogs.

Objective: To describe the characteristics of canine ocular thelaziasis in small animal clinical settings in the Republic of Korea.

Methods: Medical records of 35 dogs (44 eyes), diagnosed with thelaziasis at Dr. Park's Animal Eye Clinic between March 2022 and February 2024, were retrospectively reviewed.

Results: Nine dogs had bilateral infections, while 26 had unilateral infections. Most cases (71.4%) were referred to by local clinics, but only 16% had been initially diagnosed with thelaziasis. Common clinical signs included conjunctivitis (25.7%), ocular discomfort (17.1%), corneal ulcers (14.3%), and parasite observation (14.3%). No breed, sex, or age predisposition was noted. Thelaziasis was more prevalent in fall (54.3%) and winter (28.6%), with fewer cases in spring (11.4%) and summer (5.7%). Dogs with thelaziasis had a higher incidence of follicular conjunctivitis of the third eyelid (42.9%) compared to non-infected dogs (9.7%). All affected dogs recovered well after manual parasite removal, followed by anti-inflammatory or antibiotic eye drops as needed.

Conclusions and relevance: Canine thelaziasis showed seasonal prevalence, peaking in fall and winter, and was linked to an increased risk of follicular conjunctivitis of the third eyelid. Veterinarians should consider thelaziasis in cases of recurrent ocular surface disease, especially in these seasons.

Importance: Urinary tract infections (UTIs) are common and significant health issues in pets. Although extensive international research exists on their prevention and treatment, a notable gap remains in analyzing the characteristics of the causative bacteria.

Objective: To investigate the phylogroup, antimicrobial resistance (AMR), and molecular genotype of Escherichia coli isolates from dogs and cats with UTIs in animal clinics in Korea.

Methods: Uropathogenic E. coli (UPEC) strains were analyzed for phylogenetic grouping polymerase chain reaction, AMR, transferable resistance plasmids, and multilocus sequence typing.

Results: Sixty-seven UPECs were isolated from urine samples of dogs (n = 57) and cats (n = 10). Regarding age, the incidence of UTI was the highest in the 11 to 15 years range (46.3%, 31/67). Regarding sex, it accounted for 58.2% (n = 39) in female dogs and 11.9% (8/67) in female cats. Phylogroup B2 was the most frequent (n = 51, 75.0%) among all strains, followed by D (16.2%), A (7.4%), and B1 (1.5%). Thirty-seven (55.2%) UPECs were multidrug-resistant (MDR), and 24 (35.8%) of them belonged to phylogroup B2. Extended-spectrum cephalosporin and carbapenemase genes were detected in 18 (26.9%) UPECs and plasmids carrying these resistance genes were conjugated between strains. Thirty sequence types (STs) were identified among the total strains. Among the UPECs (n = 51) with phylogroup B2, 23 STs were identified, with ST73 being the most frequent (n = 12, 17.9%), followed by ST131 (n = 9, 13.4%).

Conclusions and relevance: Phylogroup B2 strains, particularly ST73 and ST121, were most prevalent in UPECs from Korean companion dogs and cats. For MDR UPECs, appropriate antibiotic selection is essential for the treatment of UTIs.

Importance: Evaluating Iran's national highly pathogenic avian influenza (HPAI) control program can inform vaccine selection, optimize immunization duration, guide exit strategies, and assess hemagglutination inhibition (HI) and serum neutralization (SN) methods.

Objective: To establish a serological baseline, assess antibody stability, and compare the efficacy of three HPAI (H5) vaccines.

Methods: We analyzed over 9,000 blood samples and 6,420 swabs from approximately 1.5 million birds up to 64 weeks old. HI (β, α), RT-PCR, and SN tests were conducted, with statistical analysis performed using two-way ANOVA.

Results: The serological baseline (GM titer) using H5N8 antigens from A/Chicken/Iran/162/2016 varied. The Re6+Re8 vaccine produced higher and more stable HI β titers than the H5N3 and baculovirus vaccines. Serum HI α neutralization ability was similar for Re6+Re8 and H5N3 vaccines, both 100 times greater than the baculovirus vaccine. Neutralization indices for H5N3, Re6+Re8, and baculovirus vaccines were 4.7, 4.5, and 4.2 (log2), respectively.

Conclusions and relevance: After two vaccinations, Re6+Re8 exhibited the most stable HI β antibody response, while H5N3 had the highest neutralization index, surpassing Re6+Re8 by 0.2 and the baculovirus vaccine by 0.5. These findings highlight discrepancies between HI β and SN test results, with SN being a stronger indicator of protective titers due to its in vivo methodology, compared to the in vitro HI assay.