Rotavirus A (RVA) is a major cause of acute gastroenteritis in humans and animals worldwide. As a result of the segmented nature of the rotavirus genome, genetic reassortment commonly occurs. This study aims to clarify the genetic characteristics of RVAs circulating in Indonesia. From June 2015 through August 2016, stool samples were collected from 134 children aged <5 years (71 male and 63 female) with acute gastroenteritis who were inpatients at a private hospital in Surabaya, Indonesia. All stool samples were screened for RVA antigen using immunochromatography. Forty-two samples (31.3%, 42/134) were RVA antigen-positive. All RVA positive samples tested showed the unusual combinations of G3P[8] (n = 36) and G3P[6] (n = 3) with a short RNA pattern by G/P typing and polyacrylamide gel electrophoresis (PAGE). Whole genome analysis by next-generation sequencing (NGS) was performed for 11 strains to determine the RVA genotypes. Eleven rotavirus strains were found to carry a DS-like genetic backbone; nine strains showed a G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genome constellation, which was recently reported in Australia, Hungary, Spain and Brazil; as well, two strains showed a G3-P[6]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genome constellation. The phylogenetic tree based on the VP7 gene showed that all 11 strains were classified as equine-like G3, which is genetically distinct and different in origin from typical human G3 strains. The phylogenetic tree based on the NSP4 gene showed that six strains were classified as bovine-like strain and the remaining five were classified as human strain. In conclusion, we identified the strains which are intergenogroup reassortants containing an equine-like G3 VP7, a P[8])/P[6] VP4, with a DS-1-like genetic backbone. These findings suggest that equine-like G3P[8] and P[6] RVA strains have been circulating in the Indonesian population for at least 1 year and probably longer, indicating a diversity of RVAs in this area.

Hepatitis C virus (HCV) is a major cause of liver disease and a potential cause of substantial morbidity and mortality worldwide. The overall prevalence of HCV infection is 2%, representing 120 million people worldwide. Current standard treatment using pegylated interferon and ribavirin is effective in only 50% of the patients infected with HCV genotype 1, and is associated with significant side effects. Therefore, it is still of importance to develop new drugs for treatment of HCV. Antiviral substances obtained from natural products, including medicinal plants, are potentially good targets to study. In this study, we evaluated Indonesian medicinal plants for their anti-HCV activities. Ethanol extracts of 21 samples derived from 17 species of medicinal plants explored in the East Java region were tested. Anti-HCV activities were determined by a cell culture method using Huh7.5 cells and HCV strains of 9 different genotypes (1a to 7a, 1b and 2b). Four of the 21 samples tested showed antiviral activities against HCV: Toona sureni leaves (TSL) with 50% inhibitory concentrations (IC₅₀) of 13.9 and 2.0 μg/ml against the HCV J6/JFH1-P47 and -P1 strains, respectively, Melicope latifolia leaves (MLL) with IC₅₀ of 3.5 and 2.1 μg/ml, respectively, Melanolepis multiglandulosa stem (MMS) with IC₅₀ of 17.1 and 6.2 μg/ml, respectively, and Ficus fistulosa leaves (FFL) with IC₅₀ of 15.0 and 5.7 μg/ml, respectively. Time-of-addition experiments revealed that TSL and MLL inhibited both at the entry and post-entry steps while MMS and FFL principally at the entry step. TSL and MLL inhibited all of 11 HCV strains of all the genotypes tested to the same extent. On the other hand, FFL showed significantly weaker inhibitory activities against the HCV genotype 1a strain, and MMS against the HCV strains of genotypes 2b and 7a to a lesser extent, compared to the other HCV genotypes. Ethanol extracts of TSL, MLL, MMS and FFL showed antiviral activities against all the HCV genotypes tested with the exception that some genotype(s) showed significant resistance to FFL and to MMS to a lesser extent. These plant extracts may be good candidates for the development of anti-HCV drugs.

Hepatitis C virus (HCV) infection causes not only intrahepatic diseases but also extrahepatic manifestations, including type 2 diabetes. We previously reported that HCV replication suppresses cellular glucose uptake by downregulation of cell surface expression of glucose transporter 2 (GLUT2) (D. Kasai et al., J. Hepatol. 50:883–894, 2009). GLUT2 mRNA levels were decreased in both HCV RNA replicon cells and HCV J6/JFH1-infected cells. To elucidate molecular mechanisms of HCV-induced suppression of GLUT2 gene expression, we analyzed transcriptional regulation of the GLUT2 promoter using a series of GLUT2 promoter-luciferase reporter plasmids. HCV-induced suppression of GLUT2 promoter activity was abrogated when the hepatocyte nuclear factor 1α (HNF-1α)-binding motif was deleted from the GLUT2 promoter. HNF-1α mRNA levels were significantly reduced in HCV J6/JFH1-infected cells. Furthermore, HCV infection remarkably decreased HNF-1α protein levels. We assessed the effects of proteasome inhibitor or lysosomal protease inhibitors on the HCV-induced reduction of HNF-1α protein levels. Treatment of HCV-infected cells with a lysosomal protease inhibitor, but not with a proteasome inhibitor, restored HNF-1α protein levels, suggesting that HCV infection promotes lysosomal degradation of HNF-1α protein. Overexpression of NS5A protein enhanced lysosomal degradation of HNF-1α protein and suppressed GLUT2 promoter activity. Immunoprecipitation analyses revealed that the region from amino acids 1 to 126 of the NS5A domain I physically interacts with HNF-1α protein. Taken together, our results suggest that HCV infection suppresses GLUT2 gene expression via downregulation of HNF-1α expression at transcriptional and posttranslational levels. HCV-induced downregulation of HNF-1α expression may play a crucial role in glucose metabolic disorders caused by HCV.

Hepatitis B virus (HBV) infection is a major risk factor for the development of chronic liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). A growing body of evidence suggests that HBV X protein (HBx) plays a crucial role in viral replication and HCC development. Here we identified peroxiredoxin 1 (Prdx1), a cellular hydrogen peroxide scavenger, as a novel HBx-interacting protein. Co-immunoprecipitation analysis coupled with site-directed mutagenesis revealed that the region from amino acid 17 to 20 of the HBx, particularly HBx Cys¹⁷, is responsible for the interaction with Prdx1. Knockdown of Prdx1 by siRNA significantly increased the levels of intracellular HBV RNA, HBV antigens and extracellular HBV DNA, whereas knockdown of Prdx1 did not increase the activities of HBV core, enhancer I (Enh1)/X, preS1 and preS2/S promoters. Kinetic analysis of HBV RNA showed that knockdown of Prdx1 inhibited HBV RNA decay, suggesting that Prdx1 reduces HBV RNA levels posttranscriptionally. The RNA co-immunoprecipitation assay revealed that Prdx1 interacted with HBV RNA. The exosome component 5 (Exosc5), a member of the RNA exosome complexes, was co-immunoprecipitated with Prdx1, suggesting its role in regulation of HBV RNA stability. Taken together, these results suggest that Prdx1 and Exosc5 play crucial roles in host defense mechanisms against HBV infection. IMPORTANCE HBV infection is a major global health problem. HBx plays important roles in HBV replication and viral carcinogenesis through its interaction with host factors. In this study, we identified Prdx1 as a novel HBx-binding protein. We provide evidence suggesting that Prdx1 promotes HBV RNA decay through interaction with HBV RNA and Exosc5, leading to down-regulation of HBV RNA. These results suggest that Prdx1 negatively regulates HBV propagation. Our findings may shed new light on the roles of Prdx1 and Exosc5 in host defense mechanisms in HBV infection.

Host cells have evolved host defense machinery (such as innate immunity) to eliminate viral infections. Viruses have evolved several counteracting strategies for achieving an immune escape from host defense machinery, including type I interferons (IFNs) and inflammatory cytokines. ISG15 is an IFN-inducible ubiquitin-like protein that is covalently conjugated to the viral protein via specific Lys residues and suppresses viral functions and viral propagation. Here, we demonstrate that HCV NS5A protein accepts ISG15 conjugation at specific Lys residues and that the HERC5 E3 ligase specifically promotes NS5A ISGylation. We obtained evidence suggesting that NS5A ISGylation facilitates the recruitment of CypA, which is the critical host factor for HCV replication, thereby promoting HCV replication. These findings indicate that E3 ligase HERC5 is a potential therapeutic target for HCV infection. We propose that HCV hijacks an intracellular ISG15 function to escape the host defense machinery in order to establish a persistent infection.

Group A rotavirus (RVA) is the most important cause of severe gastroenteritis among children worldwide, and effective RVA vaccines have been introduced in many countries. Here we performed a molecular epidemiological analysis of RVA infection among pediatric patients in East Java, Indonesia, during 2015–2018. A total of 432 stool samples were collected from hospitalized pediatric patients with acute gastroenteritis. None of the patients in this cohort had been immunized with an RVA vaccine. The overall prevalence of RVA infection was 31.7% (137/432), and RVA infection was significantly more prevalent in the 6- to 11-month age group than in the other age groups (P < 0.05). Multiplex reverse transcription-PCR (RT-PCR) revealed that the most common G-P combination was equine-like G3P[8] (70.8%), followed by equine-like G3P[6] (12.4%), human G1P[8] (8.8%), G3P[6] (1.5%), and G1P[6] (0.7%). Interestingly, the equine-like strains were exclusively detected until May 2017, but in July 2017 they were completely replaced by a typical human genotype (G1 and G3), suggesting that the dynamic changes in RVA genotypes from equine-like G3 to typical human G1/G3 in Indonesia can occur even in the country with low RVA vaccine coverage rate. The mechanism of the dynamic changes in RVA genotypes needs to be explored. Infants and children with RVA-associated gastroenteritis presented more frequently with some dehydration, vomiting, and watery diarrhea, indicating a greater severity of RVA infection compared to those with non-RVA gastroenteritis. In conclusion, a dynamic change was found in the RVA genotype from equine-like G3 to a typical human genotype. Since severe cases of RVA infection were prevalent, especially in children aged 6 to 11 months or more generally in those less than 2 years old, RVA vaccination should be included in Indonesia’s national immunization program.