Recently, neurological diseases associated with astroviruses (AstVs) have been reported in pigs, ruminants, minks, and humans. In 2017, neuro-invasive porcine astrovirus (Ni-PAstV) 3 was detected in the central nervous system (CNS) of pigs with encephalomyelitis in Hungary and the USA. In the process of diagnosing domestic pigs exhibiting neurological signs, histopathologic lesions of non-suppurative encephalomyelitis with meningitis, neuronal vacuolation, and gliosis were detected, and PAstV was identified using reverse transcriptase PCR in CNS samples of four pigs in three farms from August to September in 2020, South Korea. Subsequently, the ORF2 region was successfully acquired from three brain samples, facilitating subsequent analysis. Four genotypes of PAstV (PAstV1, 3, 4, and 5) were detected, and coinfection of PAstV with multiple genotypes was observed in brain samples. This is the first study to report Ni-PAstV infection in pigs in South Korea.

Astroviruses (AstVs) have been detected in a wide range of animal species, including mammals and birds. Recently, a novel AstV associated with neurological symptoms has been detected in the brains of some mammals. Raccoon dog AstV has been reported recently in China. However, there have been no reports in South Korea. Therefore, the present study aimed to detect and genetically characterize AstVs in the intestine and brain tissues of 133 wild raccoon dogs collected in Korea between 2017 and 2019. Of the seven raccoon dogs, AstVs were detected in six intestinal tissues and four brain tissues. Analysis of the capsid protein amino acid sequences of raccoon dog AstVs detected in Korea revealed a high similarity to canine AstVs, suggesting possible interspecies transmission between raccoon dogs and dogs. Phylogenetic and capsid protein amino acid sequence analysis of raccoon dog AstVs detected in the brain the 17-148B strain belonging to the HMO clade and exhibiting conserved sequences found in neurotropic AstVs (NT-AstVs), indicating their potential as NT-AstVs. However, the pathogenicity and transmission routes of the raccoon dog AstV detected in Korea have not yet been elucidated, so further research and continued surveillance for AstV in wild raccoon dogs are needed.

Eun-Jee Na, Su-Beom Chae, Jun-Soo Park, Yoon-Ji Kim, Young-Sik Kim, Jae-Ku Oem. Korean J. Vet. Serv. 2022;45:285-92. https://doi.org/10.7853/kjvs.2022.45.4.285

The emergence and evolution of avian influenza A viruses (AIVs) pose significant challenges to both public health and animal husbandry worldwide. Here, we characterized a novel reassortant highly pathogenic avian influenza virus (HPAIV), clade 2.3.4.4b H5N6, that was isolated from a mandarin duck in South Korea in December 2023. Phylogenetic and molecular analyses show that the hemagglutinin (HA) gene of the 23‐JBN‐F12‐36/H5N6 virus clustered with HPAIV clade 2.3.4.4b H5N1 viruses, which were circulating in South Korea and Japan in 2022–2023. The M and polymerase acidic (PA) genes also revealed a close association with the HPAIV clade 2.3.4.4b H5N1 AIV that was identified previously in South Korea during November 2022. Notably, the neuraminidase (NA) gene of the 23‐JBN‐F12‐36/H5N6 virus was estimated to have its origins in the HPAIV clade 2.3.4.4h H5N6 prevalent in poultry in China, and it is clustered with the AIVs that are associated with human infection cases. Taken together, these results show that the virus has been produced by reassortment with H5N1 HPAIV, which is prevalent in wild birds; H5N6 HPAIV, which is circulated in poultry in China; and the internal genes of low pathogenic avian influenza viruses (LPAIVs). In light of the reassortment of HPAIVs circulating in existing wild birds and HPAIVs circulating in poultry in China within the 2.3.4.4b H5Nx clade, it is imperative to strengthen active surveillance across wild bird populations, poultry farms, and live poultry markets, and to inform for the effective design of improved prevention and control strategies.

Astroviruses (AstVs) have been detected in a wide range of animal species, including mammals and birds. Recently, a novel AstVs associated with neurological symptoms has been detected in the brain of some mammals. Raccoon dog AstV has been reported recently in China. However, there have been no reports in South Korea. Therefore, the present study aimed to detect and genetically characterize AstVs in intestine and brain tissues of 133 wild raccoon dogs collected in Korea between 2017 and 2019. Seven wild raccoon dogs were positive for AstV, four of which were also detected in brain tissue. Analysis of the capsid protein amino acid sequences of raccoon dog AstVs detected in Korea revealed a high similarity to canine AstVs, suggesting possible interspecies transmission between raccoon dogs and dogs. Phylogenetic and capsid protein amino acid sequence analysis of raccoon dog AstVs detected in brain 17-148B strain belonged to the HMO clade and exhibited conserved sequences found in neurotropic AstVs (NT-AstVs), indicating their potential as NT-AstVs. However, the pathogenicity and transmission routes of the raccoon dog AstV detected in Korea have not yet been elucidated, so further research and continued surveillance for AstV in wild raccoon dogs are needed.

Recently, astroviruses (AstVs) have been associated with neurological symptoms in pigs, cattle, sheep, minks, muskoxes, alpacas, and humans. To investigate genotypes of porcine astrovirus (PAstV) and neuroinvasive (Ni) PAstV in South Korea, five domestic pigs with neurological symptoms from three farms were tested using reverse transcriptase PCR, histopathology, and in situ hybridization (ISH). All five genotypes of PAstV were detected in brain tissues and coinfection of PAstV with multiple genotypes was observed. To the best of our knowledge, this is the first study to report pig infection by Ni-PAstV with multiple genotypes in South Korea.