Wild aquatic birds, a natural reservoir of avian influenza viruses (AIVs), transmit AIVs to poultry farms, causing huge economic losses. Therefore, the prevalence and genetic characteristics of AIVs isolated from wild birds in South Korea from October 2019 to March 2020 were investigated and analyzed. Fresh avian fecal samples (3256) were collected by active monitoring of 11 wild bird habitats. Twenty-eight AIVs were isolated. Seven HA and eight NA subtypes were identified. All AIV hosts were Anseriformes species. The HA cleavage site of 20 representative AIVs was encoded by non-multi-basic amino acid sequences. Phylogenetic analysis of the eight segment genes of the AIVs showed that most genes clustered within the Eurasian lineage. However, the HA gene of H10 viruses and NS gene of four viruses clustered within the American lineage, indicating intercontinental reassortment of AIVs. Representative viruses likely to infect mammals were selected and evaluated for pathogenicity in mice. JB21-58 (H5N3), JB42-93 (H9N2), and JB32-81 (H11N2) were isolated from the lungs, but JB31-69 (H11N9) was not isolated from the lungs until the end of the experiment at 14 dpi. None of infected mice showed clinical sign and histopathological change in the lung. In addition, viral antigens were not detected in lungs of all mice at 14 dpi. These data suggest that LPAIVs derived from wild birds are unlikely to be transmitted to mammals. However, because LPAIVs can reportedly infect mammals, including humans, continuous surveillance and monitoring of AIVs are necessary, despite their low pathogenicity.

Adenovirus has been detected in a wide range of hosts like dogs, foxes, horses, bats, avian animals, and raccoon dogs. Canine adenoviruses with two serotypes host mammals and are members of the mastadenovirus family. Canine adenovirus type 1 (CAdV-1) and canine adenovirus type 2 (CAdV-2) cause infectious canine hepatitis and infectious bronchial disease, respectively. In this study, we investigated the prevalence of CAdV-1 and 2 in wild Nyctereutes procyonoides in Korea in 2017–2020 from 414 tissue samples, including the liver, kidney, lung, and intestine, collected from 105 raccoon dog carcasses. Only CAdV-2 was detected in two raccoon dogs, whereas CAdV-1 was not detected. Tissue samples from raccoon dogs were screened for CAdV-1 and CAdV-2 using conventional PCR. Adenovirus was successfully isolated from PCR positive samples using the Vero cell line, and the full-length gene sequence of the isolated viruses was obtained through 5’ and 3’ rapid amplification of cDNA ends (RACE). The major genes of the isolated CAdV-2/18Ra54 and CAdV-2/18Ra-65 strains showed the closest relationship with that of the CAdV-2 Toronto A26/61 strain isolated from Canada in 1976. There is no large mutation between CAdV-2, which is prevalent worldwide, and CAdV-2, which is prevalent in wild animals in Korea. In addition, it is still spreading and causing infections. The Toronto A26/61 strain, which showed the most similarity to CAdV-2/18Ra-54, was likely transmitted to wild animals through vaccinated companion animals, suggesting that further research is needed on safety measures surrounding animal vaccination. This study provides information on the genetic characteristics and prevalence of canine adenovirus in domestic wild animals and provides a better understanding of canine adenovirus.

Pseudogymnoascus is a psychrophilic fungus, which is a genus widely distributed in cold regions around the world. Recently, the presence of Pseudogymnoascus destructans (Pd), the causative agent of white-nose syndrome (WNS) belonging to Pseudogymnoascus, has been reported in neighboring countries of Korea. However, no investigation on Pd has been reported in Korea. In this study, cave-inhabiting bats and their habitats were investigated in terms of the diversity of cave fungi, and we tried to confirm the presence of Pd. Three caves suspected of hosting Pd were selected, and 83 environmental and 53 bat samples were collected. A total of 154 fungal strains belonging to 31 different genera were isolated, and 20 of 154 were confirmed to belong to Pseudogymnoascus. Pd-diagnostic PCR was performed to check whether Pd was present in the isolated Pseudogymnoascus, and seven positives were confirmed. However, phylogenetic analyses revealed that no isolates belonged or were closely related to the clade with Pd. Although samples were collected from limited areas, undescribed Pseudogymnoascus species were isolated, and it was confirmed that Korean isolates were distributed in various clades. In conclusion, it is hypothesized that Korean Pseudogymnoascus presents high diversity.

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

Neurological diseases in cattle can be caused by several infectious agents. Astroviruses are increasingly recognized as the causative agent of encephalitis in various animals, including humans. In this study, a neuroinvasive astrovirus (BoAstV 20B05) was discovered in the brain tissues of an 81-month-old Korean native cattle with neurological symptoms. Lymphocyte infiltration and multifocal perivascular cuffing were observed in the cerebrum and brain stem, and viral antigens were also detected in the meninges. In particular, the concentration of the astroviral genome was high in the brain tissues. Korean BoAstV 20B05 was classified into the CH13/NeuroS1 clade and was closely related to the Neuro-Uy and KagoshimaSR28-462 strains. Our evolutionary analysis showed that Korean BoAstV 20B05 belongs to the sub-lineage NeuroS1 and evolved independently of BoAstV KagoshimaSR28-462. These results suggest that neuroinvasive astroviruses were first introduced in Korea. However, analysis is limited by the lack of reference astrovirus sequences reported in various countries within Asia, and further analysis should be performed using more strains. In this study, we identified a neuroinvasive astrovirus infection with neurological symptoms for the first time in South Korea and confirmed that BoAstV 20B05 may have been introduced in South Korea a long time ago.

H7 low pathogenic avian influenza viruses (LPAIVs) can mutate into highly pathogenic avian influenza viruses (HPAIVs). In addition to avian species, H7 avian influenza viruses (AIVs) also infect humans. In this study, two AIVs, H7N9 (20X-20) and H7N7 (34X-2), isolated from the feces of wild birds in South Korea in 2021, were genetically analyzed. The HA cleavage site of the two H7 Korean viruses was confirmed to be ELPKGR/GLF, indicating they are LPAIVs. There were no amino acid substitutions at the receptor-binding site of the HA gene of two H7 Korean viruses compared to that of A/Anhui/1/2013 (H7N9), which prefer human receptors. In the phylogenetic tree analysis, the HA gene of the two H7 Korean viruses shared the highest nucleotide similarity with the Korean H7 subtype AIVs. In addition, the HA gene of the two H7 Korean viruses showed high nucleotide similarity to that of the A/Jiangsu/1/2018(H7N4) virus, which is a human influenza virus originating from avian influenza virus. Most internal genes (PB2, PB1, PA, NP, NA, M, and NS) of the two H7 Korean viruses belonged to the Eurasian lineage, except for the M gene of 34X-2. This result suggests that active reassortment occurred among AIVs. In pathogenicity studies of mice, the two H7 Korean viruses replicated in the lungs of mice. In addition, the body weight of mice infected with 34X-2 decreased 7 days post-infection (dpi) and inflammation was observed in the peribronchiolar and perivascular regions of the lungs of mice. These results suggest that mammals can be infected with the two H7 Korean AIVs. Our data showed that even low pathogenic H7 AIVs may infect mammals, including humans, as confirmed by the A/Jiangsu/1/2018(H7N4) virus. Therefore, continuous monitoring and pathogenicity assessment of AIVs, even of LPAIVs, are required.