Pigs are considered a “mixing vessel” that can produce new influenza strains through genetic reassortments, which threaten public health and cause economic losses worldwide. We performed surveillance of swine influenza virus (SIV) using 114,140 nasal swabs from 11,414 Korean farms from 2009 to 2022, and characterized their genetic evolution at each farm level. A total of 169 farms out of the 11,414 (1.48%) were SIV-positive. The positivity rate for the H1N2 subtype, which is most dominant in the pig population, was 37.87% (64/169). Through hemagglutinin (HA) gene analysis, 64 H1N2-positive farms were classified into Eurasian avian-like (46/64, 71.88%), triple-reassortant (14/64, 21.88%), pdm09 (3/64, 4.69%), and classical swine (1/64, 1.56%) groups. The estimated evolutionary rate of HA in H1N2 from 2009 to 2022 in Korea is 1.5309 × 10-3/site/year (95% HPD intervals from 1.0003 × 10-3 to 2.1735 × 10-3) with an estimated mean growth rate of 0.0114. Estimates of the relative genetic diversity of clades over time suggested that the HA of H1N2 exhibited an increase in population size. The results of this study showed that the Eurasian avian-like-HA of the H1N2 subtype was dominant in the pig population. The continued evolution of the HA of H1N2, which is critical for cell entry, might lead to genetic diversity and the loss of vaccine cross-protection. These results indicate that continus surveillance is imperative for monitoring the evolution of the swine influenza virus.

Canine parvovirus type-2 (CPV-2) is a major etiological agent causing gastrointestinal enteritis in domestic and wild carnivores. Since the emergence of CPV-2 in the late 1970s, subtypes CPV-2a, CPV-2b, and CPV-2c have spread worldwide. CPV-2 prevalence differed according to region and season. This study aims to investigate the prevalence of CPV-2 infection in Korea. Samples were collected from 536 dog feces in animal shelters and 225 necropsied intestinal tissues of dog carcasses submitted in the Animal and Plant Quarantine Agency (APQA) for diagnostic purposes from 2016 to 2020 in Korea. Among the 761 samples, 181 (23.8%) were positive for the following subtypes: CPV-2a (n=138), CPV-2c (n=16), CPV-2b (n=14), and CPV-2 (n=2). Feline parvovirus (n=2) and co-infection with CPV-2a and CPV-2c (n=1) were also detected. There was no significant difference in the regional distribution of CPV-2 in Korea, which is prevalent in winter. This result shows the prevalence of CPV-2 according to various environments in Korea and will be useful in establishing an effective prevention strategy against CPV-2 that reflects the situation in Korea with continuous monitoring.

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis. This study was conducted to clarify the seroprevalence of BLV in the Republic of Korea. Blood samples were obtained from Korean native cattle farms in all provinces of South Korea except Jeju. A commercial indirect enzyme-linked immunosorbent assay with 4,498 samples to detect antibodies against BLV was conducted. The results revealed that the prevalence of BLV was dependent upon age, with increasing prevalence among cattle occurring until they were 5 years old. The highest seroprevalence in cattle was observed in Chungnam (29.6%) and the lowest was observed in Jeonnam (2.6%). The mean overall prevalence for BLV antibodies in the survey was 10.2%, indicating that BLV is widespread nationwide.

Rotaviruses are double-stranded RNA viruses of the family Reoviridae, a highly diverse family of pathogens of humans and animals. In this study, we identified the lapine rotavirus from diarrheic feces of rabbits by polymerase chain reaction. In order to determine the genetic characteristics of the Korean strain, the sequences of the VP4, VP7, and NSP4 genes were determined and compared with those of reference sequences. Results of sequence and phylogenetic analyses showed that our strain was a G3P [3] rotavirus carrying the group C gene encoding NSP 4 proteins. This is the first report of an outbreak and molecular characterization of lapine rotavirus in Korea.