Journal of Veterinary Medical Science最新文献

Parrot bornavirus (PaBV), the etiological agent of proventricular dilatation disease (PDD), poses a significant threat to captive psittacine birds worldwide. This study investigated the prevalence, genotype distribution, and phylogenetic characteristics of PaBV in captive psittacine birds in Thailand. A total of 231 birds from three families (Psittaculidae, Psittacidae, and Cacatuidae) were sampled across five regions in Thailand. Nested PCR targeting the nucleoprotein gene detected PaBV in 13.85% (n=38) of samples, with 81.58% of positive cases being asymptomatic, suggesting a potential carrier state. Choanal swabs were the most effective for detecting PaBV, although some positive cases were identified exclusively in other specimen types, indicating the importance of using multiple sample types for accurate diagnosis. Genotyping revealed the presence of two viral variants: PaBV-2 and the more prevalent PaBV-4, with the latter being predominant and further classified into two distinct groups. The continued presence of PaBV in captive birds raises concern over possible spillover into native wild psittacine populations, several of which are classified as "Near Threatened" by the IUCN. These findings underscore the importance of regular monitoring and molecular surveillance in both captive and wild bird populations to inform effective disease management and conservation strategies.

African swine fever virus (ASFV) genome encodes over 170 genes, but only a small number have been investigated for their roles in disease progression. Understanding the genetic and biological functions of these lesser-known genes accelerates the specification of open reading frames involved in pathogenesis in host animals and the development of ASF vaccines. In this study, we deleted the I196L gene of the highly virulent parental strain AQS-C-1-22 to generate the ASFV mutant AQSΔI196L. In vitro, AQSΔI196L replicated similarly to the parental virus in immortalized porcine kidney macrophage cultures. Pigs intramuscularly inoculated with 10² median tissue culture infectious dose (TCID₅₀) AQSΔI196L developed similar clinical signs and consequences (e.g., high fever, anorexia, and death) as infections with the parental strain. However, viremia in AQSΔI196L-inoculated pigs was slightly reduced compared with pigs inoculated with the parental strain. These findings suggest that the I196L gene does not significantly affect the pathogenicity of the virus in pigs.

Cutaneous inverted papilloma is rarely reported in avian species. In this study, an oriental turtle dove presented with subcutaneous masses in the neck, thorax, and leg. Histopathological examination revealed an inverted proliferation of basaloid squamous epithelial cells in a cord-like, lobulated growth pattern containing Civatte/colloid body-like structures, which extend into the abundant stroma with melanosis. Proteomic analysis of formalin-fixed paraffin-embedded tissues identified Keratins 14- and 5-like proteins, with lower levels of Keratins 6A-, and 4-like proteins. Immunohistochemistry confirmed strong reactivity of Keratin 14 in the basal layers of the tumor. This case of cutaneous inverted papilloma was distinguished by unique Civatte/colloid body-like structures and the accumulation of several keratins.

This study aimed to determine the optimal stifle joint angle for the lateral fabellotibial suture (LFTS) technique in small dogs with cranial cruciate ligament rupture (CCLR), by quantitatively assessing biomechanical parameters using pressure mapping and a 3D-printed tension assistant device. LFTS procedures were performed on 12 canine hindlimb cadaveric models divided into five groups: (1) Intact group, (2) cranial cruciate ligament-deficient (CCL) group, and (3-5) stifles fixed at 90°, 105°, and 135° (L90, L105, L135). Suture tension was quantitatively measured using a tensioner. Postoperative evaluations included pedobarography, tibial rotation angle, patellofemoral contact pressure, and femorotibial contact pressure, analyzed via force-sensitive resistors and pressure-sensitive films. Pressure mapping visualizations were used to evaluate joint mechanics and pressure distribution. Statistical analyzes were conducted using two-way ANOVA with post-hoc testing. The applied suture tension differed significantly among angle-fixed groups (P<0.05). Significant correlations were observed between experimental groups and pad pressure distribution (P<0.001). No significant difference in femorotibial contact pressure was noted between the L105 and intact groups. These results suggest that a stifle angle of 105° during LFTS most closely replicates normal joint contact mechanics, offering practical insights for optimizing tensioning protocols in small dogs.

Isoleucyl-tRNA synthetase 1 (IARS1) is essential for protein synthesis. Although IARS1 mutations cause growth and metabolic disorders in humans, its role in embryonic development remains unclear. We generated Iars1 knockout (KO) mice and observed complete absence of homozygous KOs among 44 pups, indicating embryonic lethality. A χ² test confirmed significant deviation from Mendelian ratios. At E12.5, multiple resorbed implantation sites were observed, and histology at E9.5 showed embryos lacking recognizable structures. Evidence of implantation (decidual swellings with residual trophoblast and maternal vasculature) indicates post-implantation survival but failure to progress beyond early organogenesis. These results demonstrate that IARS1 is indispensable for early mouse development and provide a useful model to study the link between IARS1 deficiency and disrupted organogenesis.

Postoperative ileus (POI), commonly induced by intestinal manipulation (IM) during laparotomy, results in intestinal wall injury, inflammation, adhesion, and impaired gastrointestinal motility. This study evaluated the effects of mosapride citrate (Mos), a 5-HT₄ receptor agonist, and trehalose (Tre), a cytoprotective disaccharide, on gastrointestinal transit in an IM-induced POI mouse model. Mature male C57BL/6J mice were subjected to IM and allocated into five groups: IM + vehicle (control), IM + Mos (0.2 mg/kg, two times), IM + Tre (100 mg/kg, two times), IM + combined Mos & Tre, and IM + sequential Tre + Mos treatment. Gastrointestinal transit was quantified using phenol red method. All four treatment groups exhibited a significant increase in phenol red recovery in the lower small intestine compared with the control group (P<0.05). Notably, sequential administration (Tre + Mos) resulted in greater dye progression beyond the manipulated region than that of simultaneous (Mos & Tre) treatment (P<0.05). These findings suggest that although both agents individually promote gastrointestinal transit, the therapeutic effect is enhanced when Tre is administered first, followed by Mos. Thus, the timing and sequence of administration play a critical role in the treatment of POI. Sequential Tre + Mos therapy may represent a promising strategy for accelerating the functional restoration of gastrointestinal transit after intestinal injury.

The status of co-infection with porcine reproductive and respiratory syndrome virus type 1 (PRRSV-1) and type 2 (PRRSV-2) in Japan is poorly understood. A case of such co-infection was identified on a PRRSV-1 non-vaccinated farm in Kagoshima prefecture. Both PRRSV-1 and PRRSV-2 genomes were simultaneously detected in pig samples by RT-PCR, and molecular analysis confirmed PRRSV-1/PRRSV-2 co-infection in individual piglets. The PRRSV-1 strain (020-P4-EU) was classified as lineage 1 (sublineage: L1.2), showing high similarity to the Unistrain^® PRRS vaccine and a Korean strain. The PRRSV-2 strain belonged to lineage 4 (Cluster III). These findings provide molecular evidence of PRRSV-1/PRRSV-2 co-circulation in Japan, suggesting the complex epidemiology of PRRSV in this region.

Antimicrobial resistance in Escherichia coli is a growing concern in both human and veterinary medicine. Although fluoroquinolone-resistant (FQ-R) E. coli has been reported in companion animals, no integrated analysis incorporating antimicrobial susceptibility, clonality, resistance genes, and virulence factors (VFs) to assess human health risks has been conducted in Japan. This study aimed to characterize FQ-R E. coli isolates from companion animals in Sapporo, Japan by identifying antimicrobial susceptibility, clonality, resistance genes, and VFs. Among 106 animals sampled, 33.0% carried FQ-R E. coli. Among 104 FQ-R E. coli isolates, 58 isolates (55.8%) were identified as ST131. Whole-genome sequencing of 35 representative FQ-R E. coli isolates, including 20 ST131 isolates, showed that the ST131 isolates were distributed among five clades/sub-clades (C1-nM27, C1-M27, A, C2 and Unclassified), indicating increased clade diversity compared to previous years. ST1193, another international high-risk clone, was also detected. All isolates harbored mutations of quinolone resistance-determining regions in gyrA and parC, and 51.4% carried bla_CTX-M genes, including bla_CTX-M-27 and bla_CTX-M-14. Most isolates remained susceptible to aminoglycosides and cefmetazole, although the latter is not approved for veterinary use in Japan. Additionally, 72 VFs were identified, and eight were shared by all isolates, suggesting potential risk to human health. Our findings indicate that companion animals share certain E. coli lineages including ST131 and ST1193 with humans. Prudent antimicrobial use and routine hygiene practices are essential to limit the transmission. Further studies incorporating human and environmental isolates are needed to better understand the transmission dynamics of FQ-R E. coli within communities.

Porcine parvovirus (PPV) is a major cause of reproductive failure in pigs. This study reports the first detection of a PPV 27a-like strain in Japan. A total of 387 samples from 113 cases (2015-2024) were analyzed, revealing 35 PPV-positive cases. Phylogenetic analysis identified the NG2794-2-3/2019 strain as a 27a-like variant. Experimental infection in pregnant sows resulted in fetal death and mummification, confirming pathogenicity. The strain exhibited prolonged viremia, indicating a high transmission risk. Owing to antigenic differences from vaccine strains, conventional PPV vaccines may be ineffective. This study highlights the urgent need for enhanced vaccines to control PPV-related reproductive disorders in Japan.

The pathogenicity of avian influenza virus (AIV) is governed primarily by the hemagglutinin (HA) glycoprotein. Highly pathogenic avian influenza viruses contain a highly cleavable HA molecule susceptible to ubiquitous host proteases, such as furin, resulting in severe systemic infections. In contrast, low-pathogenic avian influenza viruses have HAs that require activation by trypsin-like proteases, restricted to specific organs, causing localized and mild infections. We generated highly pathogenic virus variants by serially passaging low-pathogenic waterfowl isolates that originally replicated poorly in domestic poultry. The increased pathogenicity was correlated with a shift from a low-pathogenic to a highly pathogenic motif in the HA cleavage site. These findings suggest that benign viruses maintained in wild waterfowl in nature have the potential to become highly pathogenic variants during circulation and adaptation in chickens. Moreover, the host specificity of AIV is also primarily determined by the HA glycoprotein. AIVs usually replicate less efficiently in humans, whereas human influenza viruses replicate poorly in birds. This host restriction largely reflects differences in receptor-binding specificity of the HA protein. Most AIVs preferentially bind to sialic acid receptors with α2,3-linked galactose (SAα2,3Gal), while human viruses prefer the SAα2,6Gal linkage. Interestingly, both receptor types are expressed in the respiratory epithelium of pigs. Swine serve as "mixing vessels" that facilitate the reassortment of viruses between avian and human strains. These results provide a molecular basis for the key mechanisms underlying the emergence of novel influenza viruses with pandemic potential in humans.