Respiratory diseases cause significant economic losses (especially in the horse racing industry). The present study describes the detection and genetic characteristics of equine herpesvirus (EHV) from a total of 1497 samples from clinically healthy horses in Korea, including 926 blood samples, 187 lung tissues, and 384 nasal swabs. EHV-2 and EHV-5 were detected in 386 (41.7%; 95% CI: 38.5–44.9) and 201 (21.7%; 95% CI: 19.1–24.4) blood samples, respectively, and in 25 (13.4%; 95% CI: 8.5–18.2) and 35 (18.7%; 95% CI: 13.1–24.3) lung tissues, respectively. EHV-1 and EHV-4 were not detected in either blood or lung tissues. EHV-1, EHV-2, and EHV-5 were detected in 46 (12.0%; 95% CI: 8.7–15.2), 21 (5.5%; 95% CI: 3.2–7.7), and 43 (11.2%; 95% CI: 8.0–14.4) nasal swabs, respectively. EHV-4 was not detected in nasal swabs. Co-infection with EHV-2 and EHV-5 was detected in 11.6% (107/926) of the blood samples and 6.4% (12/187) of lung tissues. In nasal swabs, co-infection with EHV-1, EHV-2, and EHV-5 was detected in 0.8% (3/384) of samples. Phylogenetic analysis of the glycoprotein B gene showed that EHV-1, EHV-2, and EHV-5 strains demonstrated significant genetic diversity in Korea, with a nucleotide sequence identity among them that ranged from 95.7% to 100% for EHV-1, 96.2–100% for EHV-2, and 93.8–99.3% for EHV-5. These results are the first phylogenetic analyses of EHV-1 in Korea in nasal swabs from a nationwide population of clinically healthy horses. Both EHV-2 and EHV-5 from blood, lung tissues, and nasal swabs were also detected.

A clinical case of Anaplasma bovis was reported for the first time in our previous study (2019) in a horse, a nondefinitive host. Although A. bovis is a ruminant and not a zoonotic pathogen, it is responsible for persistent infections in horses. In this follow-up study, the prevalence of Anaplasma spp., including A. bovis, was assessed in horse blood and lung tissue samples to fully understand Anaplasma spp. pathogen distribution and the potential risk factors of infection. Among 1696 samples, including 1433 blood samples from farms nationwide and 263 lung tissue samples from horse abattoirs on Jeju Island, a total of 29 samples (1.7%) tested positive for A. bovis and 31 (1.8%) samples tested positive for A. phagocytophilum, as determined by 16S rRNA nucleotide sequencing and restriction fragment length polymorphism. This study is the first to detect A. bovis infection in horse lung tissue samples. Further studies are needed to clarify the comparison of sample types within cohorts. Although the clinical significance of Anaplasma infection was not evaluated in this study, our results emphasize the need to clarify the host tropism and genetic divergence of Anaplasma to enable the development of effective prevention and control measures through broad epidemiological studies.

Background/Objectives: Tuberculosis (TB), caused by Mycobacterium tuberculosis H37Rv (M. tuberculosis), primarily affects the lungs. The Bacillus Calmette–Guérin (BCG) vaccine is the only available TB vaccine. Guinea pigs serve as an excellent preclinical model due to the similarity to human Tuberculosis pathology. However, the lack of a standardized vaccination protocol in guinea pigs causes inconsistencies in efficacy assessments, limiting precise evaluation and its application in vaccine studies. This study aims to address this gap by establishing a consistent and reliable protocol for evaluating the immunological efficacy of BCG vaccination. Methods: Guinea pigs were divided into control, M. tuberculosis-infected, and BCG-vaccinated groups. Four weeks post-vaccination, the infected and vaccinated groups were challenged with M. tuberculosis. The bacterial burden in the lungs and spleen was measured, histopathological changes were analyzed using hematoxylin and eosin (H&E) staining, and the infection levels of M. tuberculosis, as well as the presence of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ) positive cells, were evaluated through immunohistochemical (IHC) staining. Results: BCG vaccination reduced the bacterial load to 3.60 × 10⁴ CFU/lung and 5.52 × 10³ CFU/spleen compared to 3.78 × 10⁵ CFU/lung and 1.54 × 10⁴ CFU/spleen in the infected group. The mean histopathological score for lungs was 1.67 compared to 2.67 in the infected group. Similarly, the mean histopathological score for the spleen was 1.33 compared to 2.33 in the infected group. IHC analysis showed a notable reduction in M. tuberculosis and inflammatory cytokine-positive cells in the vaccinated group. The TNF-α, IL-2, and IFN-γ staining intensity decreased by 9.3, 4.8, and 11, respectively, compared to the infected group. Conclusions: This protocol enhances consistency in vaccine assessments, providing a reliable benchmark for the development of safer, more effective, and accessible TB vaccines.

Nipah virus (NiV), of the Paramyxoviridae family, causes highly fatal infections in humans and is associated with severe neurological and respiratory diseases. Currently, no commercial vaccine is available for human use. Here, eight structure-based mammalian-expressed recombinant proteins harboring the NiV surface proteins, fusion glycoprotein (F), and the major attachment glycoprotein (G) were produced. Specifically, prefusion NiV-F and/or NiV-G glycoproteins expressed in monomeric, multimeric (trimeric F and tetra G), or chimeric forms were evaluated for their properties as sub-unit vaccine candidates. The antigenicity of the recombinant NiV glycoproteins was evaluated in intramuscularly immunized mice, and the antibodies in serum were assessed. Predictably, all homologous immunizations exhibited immunogenicity, and neutralizing antibodies to VSV-luciferase-based pseudovirus expressing NiV-GF glycoproteins were found in all groups. Comparatively, neutralizing antibodies were highest in vaccines designed in their multimeric structures and administered as bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet). Additionally, while all adjuvants were able to elicit an immunogenic response in vaccinated groups, bivalent (GMYtet + GBDtet) and trivalent (Ftri + GMYtet + GBDtet) induced more potent neutralizing antibodies when administered with oil-in-water nano-emulsion adjuvant, AddaS03. For all experiments, the bivalent GMYtet + GBDtet was the most immunogenic vaccine candidate. Results from this study highlight the potential use of these mammalian-expressed recombinant NiV as vaccine candidates, deserving further exploration.

Porcine parvovirus (PPV) causes reproductive failure in sows, and vaccination remains the most effective means of preventing infection. The NADL-2 strain has been used as a vaccine for ~50 years; however, it does not protect animals against genetically heterologous PPV strains. Thus, new effective and safe vaccines are needed. In this study, we aimed to identify novel PPV1 strains, and to develop PPV1 subunit vaccines. We isolated and sequenced PPV1 VP2 genes from 926 pigs and identified ten PPV1 strains (belonging to Groups C, D and E). We selected the Group D PPV1-82 strain as a vaccine candidate because it was close to the highly pathogenic 27a strain. The PPV1-82 VP2 protein was produced in Nicotiana benthamiana. It formed virus-like particles and exhibited a 2¹¹ agglutination value. The PPV1-190313 strain (Group E), isolated from an aborted fetus, was used as the challenging strain because it was pathogenic. The unvaccinated sow miscarried at 8 days postchallenge, and mummified fetuses were all PPV1-positive. By contrast, pregnant sows vaccinated with PPV1-82 VP2 had 9–11 Log₂ antibody titers and produced normal fetuses after PPV1-190313 challenge. These results suggest the PPV1-82 VP2 subunit vaccine protects pregnant sows against a genetically heterologous PPV1 strain by inducing neutralizing antibodies.

Porcine parvovirus (PPV) 1 is a major causative pathogen of reproductive failure, and porcine circovirus (PCV) 2 is an etiological pathogen causing PCV-associated and PCV diseases worldwide. PPV2–6 and PCV3 were recently identified as newly emerging viruses with unknown pathogeneses. However, little is known of PPV1–6 and PCV3 effects or their co-infections with PCV2. In this study, we examined 926 samples (272 aborted pig fetuses and 654 pig lung tissues) from domestic pig farms for the presence of PPV1–6 or PCV3 and for PCV2 co-infection with these seven viruses. The prevalence of PPV and PCV was significantly greater in lung tissue samples than aborted pig fetus samples. PPV3–6 were detected for the first time in Korean domestic pigs. Co-infection rates with PCV2 and other viruses were significantly higher in abattoir samples than that in aborted pig fetus samples. Concurrent infections are more common than single infection in pig population and nu-merous infectious pathogens such as PPV and PCV2 can impact the respiratory diseases. Fur-thermore, Korean PPV1 strain (PPV1-82) was identical to the virulent PPV-27a strain in this respect. Our results describe, for the first time the prevalence of PPV1–6 and PCV3 infections and their co-infection rates with PCV2 in Korean domestic pigs.