The survival rate of Korean H5N1 highly pathogenic avian influenza (HPAI) viruses was investigated at different temperatures under the laboratory conditions. The estimated survival days for a starting viral concentration of 10(6.5) 50% egg infectious dose/0.1 mL were 930, 1,042, and 3,213 d at 4 degrees C; 226, 232, and 293 d at 20 degrees C; and 51, 55, and 58 d at 30 degrees C for A/chicken/Korea/ES/03, A/chicken/Korea/IS/06, and A/chicken/Korea/Gimje/08 (Gimje/08) viruses, respectively. The stability of the Gimje/08 virus was statistically significant compared with the other 2 viruses except for the data between Gimje/08 and A/chicken/Korea/IS/06 virus at 30 degrees C. This result indicated that the survival rate of 3 Korean HPAI viruses is different at various temperatures, which might have partially influenced the large scale of HPAI outbreak in Korea in 2008.

Poultry meat and eggs are vital sources of protein for human consumption worldwide. The use of several nutritional and medicinal products, including antibiotics, is crucial for efficient and safe poultry production. Accumulation of drug residues in meat and eggs from inappropriate drug use is a major concern to public health. Recently, enrofloxacin was detected (2.4–3.8 ppb) in edible eggs produced in Jeju Island, Korea. Although the farm from which the enrofloxacin-contaminated eggs were collected did not use enrofloxacin-containing products, they reported extensive use of a nutritional product (NPJ). Accordingly, in this study, we investigated whether enrofloxacin contamination had occurred accidentally in various widely used veterinary pharmaceutical products. Enrofloxacin content (4.57–179.08 ppm) in different lots of the NPJ was confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Furthermore, 76 veterinary pharmaceutical products that are widely used in poultry farms in Korea and claim to not contain enrofloxacin were collected and analyzed by LC-MS/MS. Among them, a florfenicol product and a sulfatrimethoprime product were found to contain 3.00 and 0.57 ppm enrofloxacin, respectively. These results suggest that appropriate manufacturing standards are not being followed and that strict monitoring of drug manufacturing is necessary in Korea to avoid drug contamination.

Foot-and-mouth disease virus (FMDV) is a highly contagious virus that affects cloven-hoofed animals and causes severe economic losses in the livestock industry. Given that this high-risk pathogen has to be handled in a biosafety level (BSL)-3 facility for safety reasons and the limited availability of BSL-3 laboratories, experiments on FMDV call for more attention. Therefore, we aimed to develop an FMDV experimental model that can be handled in BSL-2 laboratories. The NanoBiT luciferase (Nano-luc) assay is a well-known assay for studying protein–protein interactions. To apply the NanoBiT split luciferase assay to the diagnosis and evaluation of FMD, we developed an inactivated HiBiT-tagged Asia1 Shamir FMDV (AS-HiBiT), a recombinant Asia1 shamir FMDV with HiBiT attached to the VP1 region of Asia1 shamir FMDV. In addition, we established LgBiT-expressing LF-BK cell lines, termed LgBit-LF-BK cells. It was confirmed that inactivated AS-HiBiT infected LgBiT-LF-BK cells and produced a luminescence signal by binding to the intracellular LgBiT of LgBiT-LF-BK cells. In addition, the luminescence signal became stronger as the number of LgBiT-LF-BK cells increased or the concentration of inactivated AS-HiBiT increased. Moreover, we confirmed that inactivated AS-HiBiT can detect seroconversion in sera positive for FMDV-neutralizing antibodies. This NanoBiT split luciferase assay system can be used for the diagnosis and evaluation of FMD and expanded to FMD-like virus models to facilitate the evaluation of FMDV vaccines and antibodies.

Sin-Wook Park, Keon Kim, Chang-Yun Je, Chang-Hyeon Choi, Sang-Gyue Choi, Jong-Soo Lim, Ok-Mi Jeong, Guk-Hyun Suh, Chang-Min Lee. Korean J. Vet. Serv. 2023;46:211-8. https://doi.org/10.7853/kjvs.2023.46.3.211

Q fever is a zoonotic disease associated with reproductive losses in ruminants. This study investigated a 2025 outbreak on a Boer goat breeding farm in South Korea and compared its molecular characteristics with those of a separate 2024 outbreak. Conventional PCR targeting the IS1111 insertion element was used to test 87 goats, three female farm dogs, and four barn-level composite environmental samples. Positive goat samples underwent multiple-locus variable-number tandem-repeat analysis and multispacer sequence typing. Coxiella burnetii was detected in 60 of 87 goats (69.0%) and in one environmental sample, whereas dogs were negative. Two multiple-locus variable-number tandem-repeat profiles were identified among four goat samples, and two goats from different barns shared a profile provisionally designated MST77-like because it clustered near, but was not identical to, the MST77 reference profile. After movement restrictions, oxytetracycline treatment, environmental management, and serial monitoring, 11 of 57 previously positive goats remained positive at the second screening, and none of these 11 goats tested positive at the final examination. Complete herd clearance and the independent effect of antimicrobial treatment could not be confirmed because previously negative goats were not retested and no untreated comparison group was available. These findings support farm-wide testing, strengthened biosecurity, and follow-up monitoring.