SEN virus: response to interferon alfa and influence on the severity and treatment response of coexistent hepatitis C

The Role of Emerging and Neglected Viruses in the Etiology of Hepatitis

PURPOSE OF REVIEW

In this review, we present the overview of emerging and neglected viruses associated with liver involvement.

RECENT FINDINGS

Hepatitis E virus (HEV) emerged in the last two decades, causing hepatitis in many parts of the world. Moreover, liver involvement was also described in some emerging arboviral infections. Many reports showed dengue-associated liver injury; however, chikungunya, West Nile, tick-borne encephalitis, and Zika virus are rarely associated with clinically manifest liver disease. In addition, some neglected highly prevalent viruses such as adenoviruses and parvovirus B19 are capable of causing hepatitis in specific population groups. Anelloviruses (torque teno virus/torque teno mini virus/torque teno midi virus, SEN virus), human bocavirus, pegiviruses, and lymphocytic choriomeningitis virus have shown a little potential for causing hepatitis, but their role in the etiology of liver disease remains to be determined. In addition to the well-known hepatotropic viruses, many emerging and neglected viruses have been associated with liver diseases. The number of emerging zoonotic viruses has been increasingly recognized. While zoonotic potential of HEV is well documented, the recent identification of new hepatitis-related animal viruses such as HEV strains from rabbits and camels, non-primate hepaciviruses in domestic dogs and horses, as well as equine and porcine pegivirus highlights the possible zoonotic transmission in the context of "One Health." However, zoonotic potential and hepatotropism of animal hepatitis viruses remain to be determined.

KIR3DL1-HLA-Bw4 combination and IL28B polymorphism predict response to Peg-IFN and ribavirin with and without telaprevir in chronic hepatitis C

Natural killer cells play a key role in the immune control of viral infections. Killer immunoglobulin-like receptors (KIRs) regulate natural killer cell activation and inhibition through the recognition of their cognate HLA class I ligands. We assessed the predictive factors of a sustained virological response (SVR) in 200 Japanese patients with chronic genotype 1b hepatitis C who were treated with telaprevir (TVR), pegylated-interferon-α2b (PEG-IFN), and ribavirin (RBV) triple therapy (92 patients) or PEG-IFN/RBV therapy alone (108 patients). Sixteen KIR genotypes, HLA-A, -B and -C ligands, and an interleukin (IL) 28B polymorphism (rs8099917) were analyzed. We observed that triple therapy, white blood cell count, hemoglobin value, hepatitis C viral load, a rapid virological response (RVR), IL28B TT genotype, and KIR3DL1-HLA-Bw4 genotype were associated with an SVR. In multivariate regression analysis, we identified an RVR (P < 0.000001; odds ratio [OR] = 20.95), the IL28B TT genotype (P = 0.00014; OR = 5.53), and KIR3DL1-HLA-Bw4 (P = 0.004, OR = 3.42) as significant independent predictive factors of an SVR. In conclusion, IL28B and KIR3DL1/HLA-Bw4 are independent predictors of an SVR in Japanese patients infected with genotype 1b HCV receiving TVR/PEG-IFN/RBV or PEG-IFN/RBV therapy.

High frequency of SEN virus infection in thalassemic patients and healthy blood donors in Iran

Background

SEN virus is a blood-borne, circular ssDNA virus and possessing nine genotypes (A to I). Among nine genotypes, SENV-D and SENV-H genotypes have the strong link with patients with unknown (none-A to E) hepatitis infections. Infection with blood-borne viruses is the second important cause of death in thalassemic patients. The aim of this study was to determine the frequency of SENV-D and SENV-H genotypes viremia by performing nested-PCR in 120 and 100 sera from healthy blood donors and thalassemic patients in Guilan Province, North of Iran respectively. Also, to explicate a possible role of SEN virus in liver disease and established changes in blood factors, the serum aminotransferases (ALT and AST) and some of the blood factors were measured.

Results

Frequency of SENV-D, SENV (SENV-H or SENV-D) and co-infection (both SENV-D and SENV-H) viremia was significantly higher among thalassemic patients than healthy individuals. Frequency of SENV-H viremia was significantly higher than SENV-D among healthy individuals. In comparison to SENV-D negative patients, the mean of mean corpuscular hemoglobin was significantly higher in SENV-D positive and co-infection cases (P < 0.05). The means of AST and ALT were significantly higher in thalassemic patients than healthy blood donors, but there were not any significant differences in the means of the liver levels between SENV-positive and -negative individuals in healthy blood donors and thalassemic patients. High nucleotide homology observed among PCR amplicon's sequences in healthy blood donors and thalassemic patients.

Conclusions

The high rate of co-infection shows that different genotypes of SENV have no negative effects on each other. The high frequency of SENV infection among thalassemic patients suggests blood transfusion as main route of transmission. High frequency of SENV infection in healthy individuals indicates that other routes rather than blood transfusion also are important. Frequency of 90.8% of SENV infection among healthy blood donors as well as high nucleotide homology of sequenced amplicons between two groups can probably suggest that healthy blood donors infected by SENV act partly as a source of SENV transmission to the thalassemic patients. In conclusion, SENV-D isolate in Guilan Province may be having a pathogenic agent for thalassemic patients.

Prevalence and impact of GBV-C, SEN-V and HBV occult infections in HIV-HCV co-infected patients on HCV therapy

BACKGROUND/AIMS

It has been suggested that, in HIV-HCV co-infected patients, co-infections with other viruses may affect the response to HCV therapy. We aimed to assess the prevalence of GBV-C, SEN-V and occult HBV infections, their impact on HCV and HIV infections and on the response to HCV therapy in HIV-HCV co-infected patients.

METHODS

Three-hundred and sixty eight patients were tested before starting interferon-ribavirin for the presence of occult hepatitis B DNA, GBV-C RNA and SEN-V DNA by using real time PCR. Clinical, immunological, virological, histological characteristics and response to HCV therapy were compared according to the presence or not of each viral co-infection.

RESULTS

HBV DNA, GBV-C RNA and SEN-V DNA were found in 5 (1.4%, CI95%: 0.2-2.4%), 104 (29.9%, CI95%: 25.1-34.7%) and 209 patients (57.9%, CI95%: 52.8-63.0%), respectively. GBV-C positive patients had significantly higher CD4 count at baseline, during and after HCV therapy, even after stratification on antiretroviral treatment. No other significant difference was observed according to the presence or not of GBV-C or SEN-V co-infection, in particular regarding virological responses to HCV combination therapy.

CONCLUSIONS

There is no reason to withhold HCV therapy in HIV infected patients who have access to HAART, because of occult HBV, GBV-C or SEN-V co-infections.

Clinicopathological features and natural history of acute sporadic non-(A-E) hepatitis

AIM

The aim of the present study was to describe the clinicopathological characteristics and the natural history of acute non-(A-E) hepatitis and to assess the possible role of hepatitis G virus (HGV), TT virus (TTV) and mainly SEN virus (SENV).

METHODS

A cohort of 55 patients with sporadic acute non-(A-E) hepatitis with a mean follow up of 31 (6-55) months was studied.

RESULTS

The clinical presentation was fulminant in one (1.8%), protracted with impaired regeneration in seven (12.7%) and benign in the remaining 47 (85.5%) cases. Progression to chronic hepatitis was observed in 15 (27.3%) patients; it was more frequent in clinically severe than in non-severe cases (five of eight patients or 62.5% vs 10 of 47 patients or 21.3%, P = 0.028). Six of 10 biopsied chronic non-(A-E) cases developed cirrhosis within 10-33 months. Serum HGV-RNA was detected in 16 of 55 (29.1%) patients, TTV in 20 of 38 (52.6%) patients and SENV-D/H DNA in 20 of 55 (36.4%) cases. HGV-RNA was detected more frequently in clinically severe than in non-severe cases (five of eight or 62.5% vs 11 of 47 or 23.4%, P = 0.038). There was no other association between the presence of HGV, TTV, or SENV infection and patient characteristics or severity and outcome of disease.

CONCLUSIONS

HGV, TTV, and SENV do not seem to be responsible for the majority of sporadic acute non-(A-E) hepatitis cases. Our cohort further supports the existence of new, unknown hepatitis agent(s) with uncertain mode of transmission. The non-(A-E) agent(s) can also cause chronic hepatitis, which often has an aggressive course with rapid development of cirrhosis.

Association of cytotoxic T-lymphocyte antigen 4 gene polymorphisms with type 1 autoimmune hepatitis in Japanese

AIM

Autoimmune hepatitis (AIH) is an organ-specific autoimmune disease characterized by chronic inflammation of the liver. Although the HLA DR4 allele is associated with type 1 AIH in Japanese, the exact genetic etiology of AIH remains undefined. The cytotoxic T-lymphocyte antigen 4 (CTLA4) is an inhibitory receptor expressed by T-cells that acts largely as a negative regulator of T-cell responses, and polymorphisms of CTLA4 have been reported to be associated with susceptibility to various autoimmune diseases. Therefore, we sought to clarify whether CTLA4 single-nucleotide polymorphisms are associated with disease susceptibility in Japanese patients with type 1 AIH.

METHODS

We genotyped 76 patients with AIH and 100 ethically matched controls for allelic determinants using TaqMan genotyping assays at four polymorphism sites: -1722 and -318 in the promoter; +49 in exon 1 and +6230 in the 3' untranslated region.

RESULTS

We observed no difference in the distribution of the alleles, genotypes, or haplotypes between patients and controls. Compared with -1722 C/C patients, -1722 T/T patients were younger (56 vs. 63 years; P = 0.01) and had significantly lower serum levels of aspartate aminotransferase (313 vs. 763 IU/L; P = 0.031) and bilirubin (1.1 vs. 8.6 mg/dL; P = 0.027). Analysis of allelic frequencies revealed no significant difference between patients with and without the HLA DR4 allele.

CONCLUSION

These data suggest that the CTLA4 polymorphism is not associated with susceptibility to type 1 AIH in the Japanese population.

Molecular mechanism of hepatitis C virus replicon variants with reduced susceptibility to a benzofuran inhibitor, HCV-796

HCV-796 selectively inhibits hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase. In hepatoma cells containing a genotype 1b HCV replicon, HCV-796 reduced HCV RNA levels by 3 to 4 log(10) HCV copies/mug total RNA (the concentration of the compound that inhibited 50% of the HCV RNA level was 9 nM). Cells bearing replicon variants with reduced susceptibility to HCV-796 were generated in the presence of HCV-796, followed by G418 selection. Sequence analysis of the NS5B gene derived from the replicon variants revealed several amino acid changes within 5 A of the drug-binding pocket. Specifically, mutations were observed at Leu314, Cys316, Ile363, Ser365, and Met414 of NS5B, which directly interact with HCV-796. The impacts of the amino acid substitutions on viral fitness and drug susceptibility were examined in recombinant replicons and NS5B enzymes with the single-amino-acid mutations. The replicon variants were 10- to 1,000-fold less efficient in forming colonies in cells than the wild-type replicon; the S365L variant failed to establish a stable cell line. Other variants (L314F, I363V, and M414V) had four- to ninefold-lower steady-state HCV RNA levels. Reduced binding affinity with HCV-796 was demonstrated in an enzyme harboring the C316Y mutation. The effects of these resistance mutations were structurally rationalized using X-ray crystallography data. While different levels of resistance to HCV-796 were observed in the replicon and enzyme variants, these variants retained their susceptibilities to pegylated interferon, ribavirin, and other HCV-specific inhibitors. The combined virological, biochemical, biophysical, and structural approaches revealed the mechanism of resistance in the variants selected by the potent polymerase inhibitor HCV-796.

Anti-Helicobacter pylori seropositivity: influence on severity and treatment response in patients with chronic hepatitis C

We sought to clarify the incidence and role of Helicobacter pylori (H. pylori) seropositivity in patients with hepatitis C virus (HCV) infection and the effect of coinfection on interferon-alpha and ribavirin therapy. The presence of H. pylori was tested using a commercially available enzyme immunoassay in serum samples from 93 patients with chronic hepatitis C. Clinical features, HCV markers and response of HCV to interferon-alpha and ribavirin were compared between H. pylori-positive and H. pylori-negative patients. Anti-H. pylori antibody was detected in 45 (48%) of the 93 patients, whose median HCV-RNA level (495 vs 760 kIU/mL; P = 0.013) and platelet count (128 vs 158 x 10(3)/microL; P = 0.009) were significantly lower than in patients with HCV infection alone. Anti-H. pylori antibody levels were found to be significantly correlated with fibrosis score (P = 0.0083, r = 0.33) but inversely related to platelet count (P = 0.0037, r = -0.34). The sustained response rate for HCV clearance following interferon-alpha and ribavirin treatment did not differ between patients with and without anti-H. pylori seropositivity. The presence of H. pylori [odds ratio (OR) 8.61; 95% confidence interval (CI) 1.59-46.70] and fibrosis score (OR 30.13; 95% CI 5.44-166.78) were found by multivariate analysis to be associated with the decrease of platelet count during therapy. Coexistent H. pylori infection does not demonstrably influence the clinical course of chronic hepatitis C. A possible connection between H. pylori coinfection and thrombocytopenia was found during the treatment course, suggesting that preemptive eradication of H. pylori may facilitate completion of treatment and increased sustained virological response.

Sen Virus Infection in Patients on Peritoneal Dialysis

Background

Many reports have demonstrated SEN virus (SEN-V) infection rates in hemodialysis patients, but the SEN-V infection rate in peritoneal dialysis (PD) patients has never been reported. In this study, we determined the prevalence rate of SEN-V viremia in a PD population.

Methods

Serum samples from 47 PD patients and a control group of 43 subjects from the general population at their health examination were assayed for SEN-V-D and -H viremia using polymerase chain reaction.

Results

The proportions of female gender ( p = 0.001), previous transfusion ( p < 0.0001), and higher mean serum AST level ( p = 0.012) were significantly higher in PD patients. The prevalence rates of SEN-V-D and/or -H viremia were not significantly different between PD patients and controls (27.7% vs 32.6%). SEN-V-D(+) patients had lower mean duration of PD than SEN-V(–) patients. Mean ALT level was significantly lower in SEN-V-H(+) than in SEN-V(–) patients (12.8 ± 5.8 vs 19.6 ± 12.1 (IU/L), p = 0.025). None of the SEN-V-infected PD patients had overt clinical or biochemical signs of liver disease. There were no statistically significant differences in prevalence of SEN-V-D and/or -H viremia between automated PD (APD) patients and continuous ambulatory PD (CAPD) patients.

Conclusions

These results indicate that the SEN-V infection rate is not different between healthy individuals and PD patients. Infection with SEN-V is not associated with evident liver disease in PD patients and SEN-V infection rate is not different between APD patients and CAPD patients.

Co-infection of SENV-D among chronic hepatitis C patients treated with combination therapy with high-dose interferon-alfa and ribavirin

AIM: The clinical significance of co-infection of SENV-D among patients with chronic hepatitis C (CHC) and response of both viruses to combination therapy with high-dose interferon-alfa (IFN) plus ribavirin remain uncertain and are being investigated.

METHODS: Total 164 (97 males and 67 females, the mean age 48.1 ± 11.4 years, range: 20-73 years, 128 histologically proved) naive CHC patients were enrolled in this study. SENV-D DNA was tested by PCR method. Detection of serum HCV RNA was performed using a standardized automated qualitative RT-PCR assay (COBAS AMPLICOR HCV Test, version 2.0). HCV genotypes 1a, 1b, 2a, 2b, and 3a were determined by using genotype-specific primers. Pretreatment HCV RNA levels were determined by using the branched DNA assay (Quantiplex HCV RNA 3.0). There are 156 patients receiving combination therapy with IFN 6 MU plus ribavirin for 24 wk and the response to therapy is determined.

RESULTS: Sixty-one (37.2%) patients were positive for SENV-D DNA and had higher mean age than those who were negative (50.7 ± 10.6 years vs 46.6 ± 11.6 years, P = 0.026). The rate of sustained viral response (SVR) for HCV and SENV-D were 67.3% (105/156) and 56.3% (27/48), respectively. By univariate analysis, the higher rate of SVR was significantly related to HCV genotype non-1b (P < 0.001), younger ages (P = 0.014), lower pretreatment levels of HCV RNA (P = 0.019) and higher histological activity index (HAI) score for intralobular regeneration and focal necrosis (P = 0.037). By multivariate analyses, HCV genotype non-1b, younger age and lower pretreatment HCV RNA levels were significantly associated with HCV SVR (odds ratio (OR)/95% confidence interval (CI): 12.098/0.02-0.19, 0.936/0.890-0.998, and 3.131/1.080-9.077, respectively). The SVR of SENV-D was higher among patients clearing SENV-D than those who had viremia at the end of therapy (P = 0.04).

CONCLUSION: Coexistent SENV-D infection, apparently associated with higher ages, is found in more than one-third Taiwanese CHC patients. Both HCV and SENV-D are highly susceptible to combination therapy with high-dose IFN and ribavirin and SENV-D co-infection does not affect the HCV response. HCV genotype, pretreatment HCV RNA levels and age are predictive factors for HCV SVR.

SEN virus: epidemiology and characteristics of a transfusion-transmitted virus

SEN virus (SEN-V) is a blood-borne, single-stranded, nonenveloped DNA virus. Although its prevalence varies by geographic region, it has been detected in as many as 30 percent of postoperative transfusion recipients, compared to 3 percent of postoperative patients who did not receive transfusions. A significant association has been observed between transfusion volume and the occurrence of SEN-V infection. Transmission by transfusion also has been confirmed by the detection of greater than 99 percent homology between SEN-V in donor and recipient sera. Concurrent infections with SEN-V and hepatitis B virus, hepatitis C virus, or human immunodeficiency virus type 1 have been documented, and these observations probably reflect the blood-borne transmission of these viruses as well as SEN-V. Although SEN-V was discovered as part of a search for causes of posttransfusion hepatitis, there is no firm evidence so far that SEN-V infection either causes hepatitis or worsens the course of coexistent liver disease. Nevertheless, SEN-V appears to be transmitted by transfusion, and further studies may reveal more about its role in the future.

Prevalence of a newly identified SEN virus in China

AIM: To establish nested-PCR methods for the detection of SENV-D and SENV-H and to investigate the epidemiology of SEN virus in China.

METHODS: According to published gene sequences, primers from the conserved region were designed. Then, 135 samples from healthy voluntary blood donors and 242 samples from patients with various forms of liver disease were detected by nested-PCR of SENV-D/H. Some PCR products were cloned and sequenced.

RESULTS: By sequencing, the specificity of genotype-specific PCR was confirmed. SENV-D/H DNA was detected in 31% of the blood donors, which was higher than those in America and Italy (2%), and in Japan and Taiwan (15%-20%). The prevalence of SENV-D/H viremia was significantly higher in patients with hepatitis B and hepatitis C than in blood donors (59%-85% vs 31%, P < 0.05). The prevalence among patients with non-A-E hepatitis was significantly higher than among blood donors (68% vs 31%, P < 0.01), and equivalent to that among patients with hepatitis B and C.

CONCLUSION: Nested-PCR with genotype-specific primers could serve as a useful SENV screening assay. SENV has the same transmission modes as HBV and HCV. The high prevalence in patients with non-A-E hepatitis may attribute to the transmission modes, and SENV may not serve as the causative agents.

SEN virus does not affect treatment response in hepatitis C virus coinfected patients but SEN virus response depends on SEN virus DNA concentration

AIM: To clarify the effect of SEN virus (SENV) infection on a combination therapy including interferon alfa (IFN-α) or pegylated-IFN with ribavirin in patients with chronic hepatitis and the effect of a combination therapy on SENV.

METHODS: SENV DNA was determined by polymerase chain reaction in serum samples from 95 patients with chronic hepatitis C. Quantitative analysis was done for SENV H DNA.

RESULTS: Twenty-one (22%) of 95 patients were positive for SENV DNA. There was no difference in clinical and biochemical parameters between patients with HCV infection alone and coinfected patients. The sustained response rate for HCV clearance after combination therapy did not differ between patients with SENV (52%) and without SENV (50%, n.s.). SENV DNA was undetectable in 76% of the initially SENV positive patients at the end of follow-up. SENV H response to combination therapy was significantly correlated with SENV DNA level (P = 0.05).

CONCLUSION: SENV infection had no influence on the HCV sustained response rate to the combination therapy. Response rate of SENV to the combination therapy depends on SENV DNA level.

Clinical significance of SEN-virus on interferon response in chronic hepatitis C patients

BACKGROUND AND AIM

A novel virus, SEN-virus (SENV), was recently discovered. It has been reported as a candidate for a non-A-E hepatitis virus. However, much is still unknown about the clinical significance of SENV. The aim of the present study was to clarify the clinical significance of SENV in patients coinfected with SENV and hepatitis C virus (HCV).

METHODS

The 52 subjects had chronic hepatitis C and had undergone interferon (IFN) therapy. SEN virus DNA was investigated by using polymerase chain reaction with SENV-specific primers, which we designed to detect all strains of SENV. Additionally, SENV-D and -H were detected by consensus primers.

RESULTS

Thirty-five patients were SENV-DNA positive and 22 patients were SENV-D- or -H-positive before IFN therapy. After IFN therapy, in the HCV-RNA eradication group, all cases normalized their serum alanine aminotransferase (ALT). However, in the no eradication group, the ALT no-response rate was 68.7%. In contrast, in the SENV eradication group, the ALT no-response rate was 51.9%, and in the no eradication group, it was 37.5%. Also, in the SENV-D and -H eradication group, the ALT no-response rate was 54.5%, and in the no eradication group, it was 36.4%. The changes in ALT after IFN therapy were significantly correlated with the changes in HCV RNA, but no correlation was found with the SENV DNA presence.

CONCLUSIONS

Hepatocellular injury in patients with chronic hepatitis who are coinfected with HCV and SENV appears to primarily be caused by HCV, and is less attributable to SENV.

Insights into SEN virus prevalence, transmission, and treatment in community-based persons and patients with liver disease referred to a liver disease unit

To document the prevalence and routes of transmission of SEN virus (SEN-V) in community-based individuals and patients referred to a liver disease unit, stored serum samples obtained from 160 Canadian Inuit and 140 patients with liver disease were tested for SEN-V DNA by polymerase chain reaction. In the community-based population, SEN-V was present in 57 (36%) of 160 persons. SEN-V-positive individuals tended to be younger and were more often male. Liver enzyme levels and serologic markers for hepatitis A and B viruses were similar in SEN-V-positive and SEN-V-negative individuals. SEN-V was present in 30 (21%) of the 140 patients with liver disease. Age, sex, risk factors for viral acquisition, prevalence of symptoms, and liver biochemical and histological findings were similar in SEN-V-positive and SEN-V-negative patients. These results indicate that SEN-V infection is a common viral infection in both healthy individuals and patients with chronic liver disease, that transmission likely occurs via nonparenteral routes, and that SEN-V infection is not associated with higher rates of or more-severe liver disease in persons with preexisting liver disease.

Non-A to E hepatitis

PURPOSE OF THE REVIEW

The list of possible hepatotropic viruses continues to grow with the discovery of the GB virus-C, the TT virus and the SEN virus. There is emerging data on the biology of these newly discovered :In spite of continuing research into the pathogenicity of the GB virus-C and the TT virus, definite evidence linking them to acute or chronic liver disease is lacking. The SEN virus was reported in 2000, and although there seems to be an association between virus and transfusion-related hepatitis, more data are awaited before definite conclusions can be drawn. The effect of GB virus-C, the TT virus and the SEN virus co-infection on other viral and non-viral hepatitides has also been studied in some detail. Again, there is no definite evidence so far that these viruses modify other liver diseases.

SUMMARY

At the present time, diagnostic testing for these viruses does not seem to be warranted outside of clinical studies. The discovery of these viruses, however, paves the way for further research into novel viral agents that infect humans, other among hosts.