Tomoko Kiyohara

Interleukin-1 and tumor necrosis factor-α trigger restriction of hepatitis B virus infection via a cytidine deaminase activation-induced cytidine deaminase (AID).

Background: Cytokines and host factors triggering innate immunity against hepatitis B virus (HBV) are not well understood. Results: IL-1 and TNFα induced cytidine deaminase AID, an anti-HBV host factor, and reduced HBV infection into hepatocytes. Conclusion: IL-1/TNFα reduced host susceptibility to HBV infection through AID up-regulation. Significance: Proinflammatory cytokines modulate HBV infection through a novel innate immune pathway involving AID. Virus infection is restricted by intracellular immune responses in host cells, and this is typically modulated by stimulation of cytokines. The cytokines and host factors that determine the host cell restriction against hepatitis B virus (HBV) infection are not well understood. We screened 36 cytokines and chemokines to determine which were able to reduce the susceptibility of HepaRG cells to HBV infection. Here, we found that pretreatment with IL-1β and TNFα remarkably reduced the host cell susceptibility to HBV infection. This effect was mediated by activation of the NF-κB signaling pathway. A cytidine deaminase, activation-induced cytidine deaminase (AID), was up-regulated by both IL-1β and TNFα in a variety of hepatocyte cell lines and primary human hepatocytes. Another deaminase APOBEC3G was not induced by these proinflammatory cytokines. Knockdown of AID expression impaired the anti-HBV effect of IL-1β, and overexpression of AID antagonized HBV infection, suggesting that AID was one of the responsible factors for the anti-HBV activity of IL-1/TNFα. Although AID induced hypermutation of HBV DNA, this activity was dispensable for the anti-HBV activity. The antiviral effect of IL-1/TNFα was also observed on different HBV genotypes but not on hepatitis C virus. These results demonstrate that proinflammatory cytokines IL-1/TNFα trigger a novel antiviral mechanism involving AID to regulate host cell permissiveness to HBV infection.

INFECTION OF A CHIMPANZEE WITH HEPATITIS C VIRUS GROWN IN CELL CULTURE

Culture supernatant harvested from Daudi cells, a lymphoplastoid cell line, after 58 days of infection with the H77 strain of hepatitis C virus (HCV), was inoculated into a chimpanzee. HCV RNA, as detected by RT-PCR, first appeared in the serum and liver 5 and 6 weeks, respectively, after inoculation. Peripheral blood mononuclear cells (PBMC) collected on week 7 were also positive for HCV RNA. The major sequences of hypervariable region 1 (HVR1) of the viral genome recovered from the inoculated chimpanzee were the ones which were the majority in the original H77 inoculum and not those which were in the majority in the culture supernatant. Only the sequence recovered from PBMC was the same as the major one found in the cell culture.

Shifting Seroepidemiology of Hepatitis A in Japan, 1973–2003

Background. Hepatitis A infection is caused by hepatitis A virus (HAV) contracted through fecal‐oral transmission. Life‐long immunity is conferred after infection. Improved sanitary conditions have generally resulted in a significant decline in the incidence of hepatitis A. However, a low incidence of infection results in increased HAV susceptibility. The present study investigates the prevalence of anti‐HAV antibody and clarifies the current HAV status and HAV susceptibility in Japan at 2003. Methods. A total of 2,430 serum specimens collected during 2003 from Japanese individuals ranging in age from 0–92 years, were tested for anti‐HAV antibody using an inhibition enzyme linked immunosorbent assay. All specimens were obtained from the WHO and the National Serum Reference Bank/National Institute of Infectious Diseases, Tokyo, Japan. Results. The overall seroprevalence was 12.2%. Anti‐HAV antibodies were rarely detected in individuals between 0–44 years of age. Starting from the age of 45–49 years, seropositivity gradually increased through age 65 years and above. Seroprevalence was not affected by gender, and geographic distribution did not affect age‐specific seroprevalence until the age of 60 years. Conclusions. HAV susceptibility in Japan is increasing annually. Particularly, the prevalence of anti‐HAV antibody in individuals older than 50 years in 2003 was 50.3%, which is significantly lower than that of corresponding studies in 1994 (74.3%), 1984 (96.9%) and 1973 (96.9%). The growing susceptible population of advanced age results in more frequent HAV infection among them. The surveillance of anti‐HAV antibody prevalence is useful for implementing preventive measures and for controlling the spread of HAV.

Antigen-loaded dissolving microneedle array as a novel tool for percutaneous vaccination.

Antigen-loaded dissolving microneedle array (dMNA) patches were investigated as novel systems for vaccine delivery into the skin, where immuno-competent dendritic cells are densely distributed. We fabricated micron-scale needles arrayed on patches, using chondroitin sulfate mixed with a model antigen, ovalbumin. Insertion of dMNA effectively delivered substantial amounts of ovalbumin into the skin within 3 min and induced robust antigen-specific antibody responses in the sera of mice. The antibody dose-response relationship showed that the efficiency of dMNA patch immunization was comparable to that of conventional intradermal injections. Thus, Antigen-loaded dMNA patches are a promising antigen-delivery system for percutaneous vaccination.

Hepatitis A outbreak associated with a revolving sushi bar in Chiba, Japan : Application of molecular epidemiology

Aim:  The number of hepatitis A cases in Japan as well as in other developed countries has been progressively decreasing during the last several years. There is no universal hepatitis A vaccination program in Japan, and a hepatitis A virus (HAV) epidemic in Japan is not unlikely. In 2011, a hepatitis A outbreak associated with a revolving sushi bar occurred in Chiba, Japan. We aimed to analyze this outbreak.

Inhibitory effects on HAV IRES-mediated translation and replication by a combination of amantadine and interferon-alpha

Hepatitis A virus (HAV) causes acute hepatitis and sometimes leads to fulminant hepatitis. Amantadine is a tricyclic symmetric amine that inhibits the replication of many DNA and RNA viruses. Amantadine was reported to suppress HAV replication, and the efficacy of amantadine was exhibited in its inhibition of the internal ribosomal entry site (IRES) activities of HAV. Interferon (IFN) also has an antiviral effect through the induction of IFN stimulated genes (ISG) and the degradation of viral RNA. To explore the mechanism of the suppression of HAV replication, we examined the effects of the combination of amantadine and IFN-alpha on HAV IRES-mediated translation, HAV replicon replication in human hepatoma cell lines, and HAV KRM003 genotype IIIB strain replication in African green monkey kidney cell GL37. IFN-alpha seems to have no additive effect on HAV IRES-mediated translation inhibition by amantadine. However, suppressions of HAV replicon and HAV replication were stronger with the combination than with amantadine alone. In conclusion, amantadine, in combination of IFN-alpha, might have a beneficial effect in some patients with acute hepatitis A.

Epidemiological and genetic analyses of a diffuse outbreak of hepatitis A in Japan, 2010.

BACKGROUND Hepatitis A virus (HAV) is still one of the most common causative agents of acute hepatitis in Japan. Although a relatively small number of annual acute hepatitis A cases (approximately 100-150, 0.78-1.17 per million) were recently reported, a larger number of cases (346, 2.71 per million) were reported in 2010. OBJECTIVES To investigate the causes of the 2010 HAV resurgence in Japan by using molecular epidemiological and genetic analyses. STUDY DESIGN HAV specimens were obtained from 61 cases from 22 different prefectures. These viral specimens were genotyped by PCR amplification and sequencing of the VP1/2A region of HAV genome. RESULTS Phylogenetic analysis revealed that 61 HAV strains could be divided into three genotypes: IA (44 cases), IB (1 case) and IIIA (16 cases). The IA genotype consisted of two genomic sub-lineages. The sequences of one of the two IA sub-lineages (corresponding to 31 cases) were very similar, 26 of these 31 isolates had 100% identity. The other IA sub-lineage corresponded to strains endemic to Japan. The sequences of Japanese IIIA strains were similar to those of strains that caused a large epidemic in the Republic of Korea from 2007 to 2009. CONCLUSIONS The resurgence of HAV in 2010 can be attributed to importation of two newly emerged HAV genotypes.

Possible widespread presence of hepatitis A virus subgenotype IIIA in Japan: Recent trend of hepatitis A causing acute liver failure.

Aim:  Recently, the number of acute hepatitis A cases has decreased in Japan. However, six patients with acute liver failure caused by hepatitis A virus (HAV) have been admitted to Chiba University Hospital, Japan, in the last 18 months, between 2010 and June 2011. The aim of this study is to characterize the recent HAV genotypes from an urban hospital in Japan and to compare the clinical differences.

Interleukin-29 suppresses hepatitis A and C viral internal ribosomal entry site-mediated translation.

Our aim was to investigate the effects of interferons (IFNs)-λ (interleukin-29 [IL-29], IL-28A, and IL-28B) on hepatitis C virus (HCV) and hepatitis A virus (HAV) internal ribosomal entry site (IRES)-mediated translation. The effects of these IFNs on HCV/HAV translation from HAV/HCV IRES were investigated using bicistronic reporter constructs. We transfected HCV/HAV IRES constructs into these IFN-expressing cell lines. IL-29 showed stronger inhibition of their IRES-mediated translation. Combining IL-29 with IFN-α or amantadine resulted in stronger inhibition of HAV IRES activity. Our findings demonstrated a novel antiviral effect of IFNs-λ against HAV and HCV through the suppression of IRES-mediated translation.

An in‐house‐anti‐hepatitis A virus (HAV)‐specific immunoglobulin M capture enzyme‐linked immunosorbent assay: Evaluation and application to an HAV outbreak

An anti‐hepatitis A virus (HAV)‐specific immunoglobulin M capture enzyme‐linked immunosorbent assay (anti‐HAV IgM ELISA) kit was re‐designed for laboratory use and compared with a commercial anti‐HAV IgM detection system using 58 serum samples collected from patients, vaccines, and healthy individuals. Because concordance between the two systems was high (r = 0.93, P < 0.05), 19 sets of serum and fecal samples obtained from individuals exposed to an HAV outbreak were also examined. Serum levels of anti‐HAV IgM were determined using the in‐house ELISA kit and the HAV genome in fecal samples was detected using the polymerase chain reaction (PCR). Among the 19 sets of sample, 14 were positive for both anti‐HAV IgM and the HAV genome. All of those whose serum samples were anti‐HAV IgM negative were also negative for the HAV genome in fecal samples. The results of the in‐house IgM ELISA were consistent with those of the HAV genome detected by PCR and with the commercial IgM ELISA. The in‐house anti‐HAV IgM ELISA kit was therefore proven suitable for laboratory use and applicable to epidemiological studies of HAV infection. J. Med. Virol. 81:1513–1516, 2009.