The African swine fever virus (ASFV) was first detected in wild boar in the Demilitarized Zone, a bordered area between South and North Korea, on 2 October 2019. Phylogenetic analyses of ASFV genes encoding p72 and CD2v indicated that the causative strain belongs to genotype II and serogroup 8, respectively, and contained additional tandem repeat sequences between the I73R and the I329L protein genes.

Hepatitis C virus (HCV) is highly dependent on host proteins for its own propagation. By transcriptome sequencing (RNA-Seq) analysis, we identified 30 host genes that were significantly differentially expressed in cell culture-grown HCV (HCVcc)-infected cells. Of these candidate genes, we selected and characterized ankyrin repeat domain 1 (ANKRD1). Here, we showed that protein expression of ANKRD1 was up-regulated in HCVcc-infected cells. We further showed that protein expression level of ANKRD1 was increased by nonstructural 5A (NS5A) protein. ANKRD1 specifically interacted with NS5A both in vitro and coimmunoprecipitation assays. Protein interaction was mediated through the domain II of NS5A and the C-terminal region of ANKRD1. Promoter activity of ANKRD1 was also increased by NS5A protein. Moreover, up-regulation of ANKRD1 expression was mediated through alteration in intracellular calcium homeostasis and ER stress in HCVcc-infected cells. We showed that silencing of ANKRD1 impaired HCV propagation without affecting HCV replication. By using HCV-like infectious particle (HCV-LP), we demonstrated that HCV single-cycle infection was drastically impaired in ANKRD1 knockdown cells. Finally, we verified that ANKRD1 was required for HCV entry. These data suggest that HCV coopts ANKRD1 for its own propagation and up-regulation of ANKRD1 may contribute to HCV-mediated liver pathogenesis.

Bats have increasingly been recognized as the natural reservoir of severe acute respiratory syndrome (SARS), coronavirus, and other coronaviruses found in mammals. However, little research has been conducted on bat coronaviruses in South Korea. In this study, bat samples (332 oral swabs, 245 fecal samples, 38 urine samples, and 57 bat carcasses) were collected at 33 natural bat habitat sites in South Korea. RT-PCR and sequencing were performed for specific coronavirus genes to identify the bat coronaviruses in different bat samples. Coronaviruses were detected in 2.7% (18/672) of the samples: 13 oral swabs from one species of the family Rhinolophidae, and four fecal samples and one carcass (intestine) from three species of the family Vespertiliodae. To determine the genetic relationships of the 18 sequences obtained in this study and previously known coronaviruses, the nucleotide sequences of a 392-nt region of the RNA-dependent RNA polymerase (RdRp) gene were analyzed phylogenetically. Thirteen sequences belonging to SARS-like betacoronaviruses showed the highest nucleotide identity (97.1-99.7%) with Bat-CoV-JTMC15 reported in China. The other five sequences were most similar to MERS-like betacoronaviruses. Four nucleotide sequences displayed the highest identity (94.1-95.1%) with Bat-CoV-HKU5 from Hong Kong. The one sequence from a carcass showed the highest nucleotide identity (99%) with Bat-CoV-SC2013 from China. These results suggest that careful surveillance of coronaviruses from bats should be continued, because animal and human infections may result from the genetic variants present in bat coronavirus reservoirs.

Bats have been identified as a natural reservoir for several potentially zoonotic viruses. Recently, astroviruses have been reported in bats in many countries, but not Korea. We collected 363 bat samples from thirteen species at twenty-nine sites in Korea across 2016 and tested them for astrovirus. The detection of the RNA-dependent RNA polymerase (RdRp) gene in bat astroviruses was confirmed in thirty-four bats across four bat species in Korea: twenty-five from Miniopterus fuliginosusi, one from Myotis macrodactylus, four from M. petax, and four from Rhinolophus ferrumequinum. The highest detection rates for astrovirus were found in Sunchang (61.5%, 8/13 bats), and in the samples collected in April (63.2%, 12/19 bats). The amino acid identity of astroviral sequences identified from bat samples was ≥ 46.6%. More specifically, the amino acid identity within multiple clones from individual bats was ≥ 50.8%. Additionally, the phylogenetic topology between astroviruses from different bat families showed a close relationship. Furthermore, phylogenetic analysis of the partial ORF2 sequence of bat astroviruses was found to have a maximum similarity of 73.3-74.8% with available bat astrovirus sequences. These results indicate potential multiple-infection by several bat astrovirus species in individual bats, or hyperpolymorphism in the astrovirus strains, as well as the transmission of astroviruses across bat families; furthermore, our phylogenetic analysis of the partial ORF2 implied that a novel astrovirus may exist. However, the wide diversity of astroviral sequences appeared to have no significant correlation with bat species or the spatiotemporal distribution of Korean bat astroviruses.

Saponins are a group of naturally occurring plant glycosides which possess a wide range of pharmacological properties, including anti-tumorigenic and antiviral activities. To investigate whether saponin has anti-hepatitis C virus (HCV) activity, we examined the effect of saponin on HCV replication. HCV replication was efficiently inhibited at a concentration of 10 µg/ml of saponin in cell culture grown HCV (HCVcc)-infected cells. Inhibitory effect of saponin on HCV replication was verified by quantitative real-time PCR, reporter assay, and immunoblot analysis. In addition, saponin potentiated IFN-α-induced anti-HCV activity. Moreover, saponin exerted antiviral activity even in IFN-α resistant mutant HCVcc-infected cells. To investigate how cellular genes were regulated by saponin, we performed microarray analysis using HCVcc-infected cells. We demonstrated that suppressor of cytokine signaling 2 (SOCS2) protein level was distinctively increased by saponin, which in turn resulted in inhibition of HCV replication. We further showed that silencing of SOCS2 resurrected HCV replication and overexpression of SOCS2 suppressed HCV replication. These data imply that saponin inhibits HCV replication via SOCS2 signaling pathway. These findings suggest that saponin may be a potent therapeutic agent for HCV patients.