SEN Virus Infection Research Articles

Molecular epidemiology of SEN virus among blood donors and renal dialysis patients.

The SEN virus (SEN-V) is a single-stranded circular, non-enveloped DNA virus that has been linked to blood transfusion and is thought to be a major cause of post-transfusion hepatitis. The two SENV types, SENV-H and SENV-D, are non-A to E hepatitis viruses in those who are infected. The purpose of this study is to find out how common SENV and its variations are among renal dialysis patients and healthy blood donors. The study used a cross-sectional design, with 300 blood samples collected from KFMMC patients, 150 from healthy blood donors and 150 from renal dialysis patients, between January 2019 and January 2021. The samples were screened for the presence of SENV-D andSENV-H.using nested PCR. Molecular analysis of the SEN virus revealed that 9.3% of the samples (14 out of 150) tested positive for SEN virus infection in renal dialysis patients. The data from healthy donors revealed that 10% of the samples tested positive for the SEN virus (15 out of 150). The presence of SEN-V in healthy blood donors and renal dialysis patients demonstrates the virus's blood-borne nature and emphasizes the dangers of blood-borne transmission.

SEN virus genotype H distribution in β-thalassemic patients and in healthy donors in Iraq: Molecular and physiological study.

The SEN virus (SENV) has been linked to transfusion-associated non-A-E hepatitis; however, information regarding SENV infections in patients with thalassemia, particularly in those with hepatitis virus co-infections, remains limited. This study investigated the frequency of SENV (genotypes D and H) infections in Iraqi patients with thalassemic patients infected and not infected with hepatitis C virus. The study involved 150 β-thalassemia patients (75 with HCV infections and 75 without) and 75 healthy blood donors. Patient levels of vitamins C and E, liver function markers, and glutathione peroxidase (GPX) were determined. Recovered viral nucleic acids were amplified using the conventional polymerase chain reaction (SENV DNA) or the real-time polymerase chain reaction (HCV RNA) techniques. Only 10% of healthy donors had evidence of SENV infection. Among patients with thalassemia, 80% and 77% of patients with and without concurrent HCV infections, respectively, had SENV infections. DNA sequencing analyses were performed on blood samples obtained from 29 patients. Patients with thalassemia, particularly those with SENV infections, had higher levels of several enzymatic liver function markers and total serum bilirubin (P < 0.05) than did healthy blood donors. Among the examined liver function markers, only gamma-glutamyl transferase demonstrated significantly higher levels in HCV-negative patients infected with SENV-H than in those infected with SENV-D (P = 0.01). There were significantly lower vitamin C, vitamin E, and glutathione peroxidase levels in patients than in healthy donors (P < 0.05), but only glutathione peroxidase levels were significantly lower in HCV-negative thalassemia patients infected with SENV than in those without SENV infections (P = 0.04). The SENV-H genotype sequences were similar to the global standard genes in GenBank. These results broaden our understanding the nature of the SENV-H genotype and the differential role of SENV-H infections, compared to SENV-D infections, in patients with thalassemia, in Iraq.

SEN virus detection in thalassemic patients infected with hepatitis C virus

HCV infection is known to be associated with clinical complications in thalassemic patients. D and H genotypes of SEN virus (SENV) are associated with blood-product transfusion and possibly non-A-to-E hepatitis. In this study, SENV viremia and its effect on liver ALT level in thalassemic patients, thalassemic patients infected with HCV, and HCV-infected patients were examined. Semi-nested PCR was conducted for detection of genotype H and D DNA, and the level of alanine aminotransferase (ALT) was measured. There was no significant difference in the mean ALT level in the studied groups and between SENV-positive and SENV-negative individuals. The results also showed that SENV infection does not affect the ALT level in these patients.

The prevalence of SEN virus infection in blood donors and chronic hepatitis B and C patients in Chaharmahal Va Bakhtiari province

SEN virus (SEN-V) is a blood-borne, circular, nonenveloped and single-stranded DNA virus. Phylogenetic analysis demonstrated 9 different genotypes for this virus. SEN-V could be related to post-transfusion hepatitis and infections with this virus in blood donors and hepatitis patients differ markedly by geographic region. The purpose of present study was to determine the prevalence of H and D genotypes of SEN-V (SENV-H and SENV-D) infection in blood donors and patients with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) for the first time in Chaharmahal Va Bakhtiari province located in southwest Iran. SEN-V DNA was analyzed in 240 serum samples of the patients with chronic HBV and HCV (172 HBV and 68 HCV) and 60 non-professional blood donors from the blood transfusion organization, hospital and clinical and pathological laboratories in Chaharmahal Va Bakhtiari province. SEN-V DNA was amplified by specific primers for SENV-H and SENV-D genotypes using polymerase chain reaction (PCR) method after extraction of DNA from sera and PCR products were visualized in a 1% agarose gel electrophoresis. SENV-H genotype was found to be positive in 54/172 (31.39%), 23/68 (33.82%), and 8/60 (13.33%) and SENV-D genotype was detected in 48/172 (27.91%), 27/68 (39.7%), and 6/60 (10%) of patients with chronic HBV, HCV and healthy blood donors, respectively. These results showed that high prevalence of SEN-V infection in patients with chronic HBV and HCV compared healthy blood donors in Chaharmahal Va Bakhtiari province using T test statistical analysis (P<0.05). According to these findings examination of serum samples for control and prevention of SEN-V infection in hepatitis patients and healthy blood donors seems to be necessary .

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

BackgroundSEN 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.ResultsFrequency 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.ConclusionsThe 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.

OP6-6 High frequency of SEN virus infection in thalassemic patients and healthy blood donors in Iran

OP6-6 High frequency of SEN virus infection in thalassemic patients and healthy blood donors in Iran

Prevalence of SEN virus genotype-D and genotype-H among haemodialysed patients

Aim: A recently discovered DNA virus (SEN virus) has been assumed to be responsible for post-transfusion hepatitis in humans. Phylogenetic analysis of the SEN virus (SEN-V) has revealed the existence of 8 different genotypes (A-H). SEN-V genotype-H (SENV-H) and SEN-V genotype-D (SENV-D) have been described as most closely associated with post-transfusion hepatitis. So far, it is unclear whether patients on maintenance haemodialysis are at increased risk for acquiring the SEN virus. The aim of the present study was to investigate the prevalence of SENV-D and SENV-H among patients on maintenance haemodialysis. Materials and Methods: Serum samples derived from 100 haemodialysed patients were examined for SENV-D and SENV-H viraemia by polymerase chain reaction (PCR). One hundred and twenty serum samples were obtained from healthy blood donors, who served as the control group. Results: The prevalence of SENV-D was 33% (n = 33) while that of SENV-H was 22% (n = 22) among the patients on maintenance haemodialysis. The prevalence of SENV-D was 5% (n = 6) while that of SENV-H was 20% (n = 24) among the healthy blood donors. Our data suggest that SEN-V infection was significantly more prevalent (P < 0.05) in patients on haemodialysis (55%) than in control subjects (25%). Conclusions: These findings reveal that patients on maintenance haemodialysis are at risk of SEN-V infection. Another important finding is the relatively high prevalence (25%) of SEN-V in healthy blood donors in our region.

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

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

The prevalence of SEN virus infection in blood donors in Iran.

SEN virus is a blood-borne, single-stranded, nonenveloped DNA virus. Two of its strains (D and H), appear to be associated with non-A-to-E hepatitis more frequently than the others, although it is not clear whether this observation has any significance. The prevalence of SEN virus in otherwise healthy individuals, including blood donors, differs markedly by geographic region. In this study, an investigation to evaluate the prevalence of SEN virus strains among blood donors in Tehran was carried out. Sera of 260 blood donors who were negative for hepatitis B surface antigen (HBsAg) and third-generation hepatitis C virus antibody (anti-HCV) were tested for SEN virus-D and -H DNA. DNA was extracted from plasma of 260 blood donors and amplified by semi- nested polymerase chain reaction. SEN virus-D viremia was detected in four (1.5%) of the 260 blood donors (95% confidence interval (CI), 0.0 - 3%). SEN virus-H viremia was detected in 47 (18.08%) of the 260 blood donors (95% CI, 13.4 - 22.8%). Both SEN virus-D and SEN virus-H viremia were detected in nine (3.4%) of the 260 blood donors (95% CI, 1.2 - 5.7%). SEN virus-D or SEN virus-H viremia was identified in 60 (23.08%) of the 260 blood donors (95% CI, 18.08 - 28.08%). Out of the 260 blood donors, 60 (23%) were infected by SEN virus-D/H. The prevalence of SEN virus-H is more than SEN virus-D. Our results also showed that the high prevalence of SEN virus in healthy blood donors with no history of blood transfusion may attribute to the transmission modes other than parenteral transmission.

SEN virus (SENV) co-infection in patients with chronic hepatitis C

Aim: We wanted 1) to determine the prevalence of SENV DNA in patients (pts) with chronic HCV infection, 2) to evaluate the effect of SENV infection on PEG-IFN+RBV induced SVR and 3) to assess the effect of anti-HCV therapy on SENV elimination.

Prevalence and clinical significance of SEN virus infection in patients with non A-E hepatitis and volunteer blood donors in Shanghai

To explore the prevalence of SEN virus (SENV) in patients with non A-E hepatitis and volunteer blood donors in Shanghai. According to the published gene sequences, primers from the conserved region were designed. Then, the prevalence of SEN virus in 30 samples from healthy voluntary blood donors and 30 samples from patients with non A-E hepatitis were detected by nested-PCR of SENV-D/H. Some PCR products were cloned and sequenced. The specificity of genotype-specific PCR was confirmed by sequencing, the SENV DNA was detected in 53.3% of the patients with non A-E hepatitis and 10% of the blood donors. The prevalence of SENV-D/H viremia was significantly higher in patients with non A-E hepatitis than in blood donors (P = 0.0002). SENV-H subtype and SENV-D subtype were found in 2 and 1 samples, respectively from blood donors. SENV-H subtype, SENV D subtype, mixed SENV-D and SENV-H subtype were found in 8, 6 and 2 samples, respectively, from patients with non A-E hepatitis. The gene type of SENV in patients with non A-E hepatitis and blood donors in shanghai is D or H subtype, and transfusion is not the only transmitting form of SENV.

SEN and Hepatitis Virus Infections in Nontransfused Children and Pediatric Thalassemia Patients with Multiple Transfusions in Taiwan

Background: SouthernTaiwan is a hepatitis B and C viruses (HBV, HCV) endemic area. SEN virus (SENV) infection has been suggested as transfusion-related hepatitis. Two variants of SENV (SENV-D and SENV-H) have been studied in non-transfused children and transfusion-dependent thalassemia patients. Methods: Sera of 67 non-transfused children and 55 pediatric thalassemia patients with multiple transfusions were tested for SENV-D and SENV-H DNAs, liver function, iron status, HBV and HCV markers. Results: The prevalence of SENV (D or H), SENV-D, SENV-H infection, and SENV-D/H coinfection was significantly lower in nontransfused children than in thalassemia patients (22.4, 20.9, 5.0 and 1.5%, respectively, versus 67.3, 52.7, 40.0 and 25.5%, respectively, p < 0.001). The serum alanine aminotransferase (ALT) levels in thalassemia patients with SENV infection alone were significantly lower than levels in patients with SENV/HCV co-infection (p < 0.05), but not different when compared with those without SENV/HCV infection. SENV viremia was not associated with elevated ALT levels in thalassemia patients. SENV viremia did not increase the risk of HCV infection in thalassemia patients. Conclusions: SENV infection is high among non-transfused controls in Taiwan. Transfusion significantly increases the relevance of SENV infection. SENV viremia was not associated with the ALT levels in thalassemia patients.

Sen Virus Infection in Patients on Peritoneal Dialysis

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. 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. 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. 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.

Detection of SEN virus in the general population and different risk groups in Slovakia

Sera of 426 adult persons were examined to assess the prevalence of SEN virus (SENV) infection in Slovakia and to determine the importance of different risk factors for parenteral transmission. SENV prevalence was determined by the PCR method using primers of SENV-D and SENV-H strains. Positive results were found in 10 of 37 patients with acute hepatitis of unknown etiology, 7 of 38 with acute hepatitis B, 17 of 44 with chronic hepatitis B, 29 of 102 with chronic hepatitis C, 36 of 72 hemodialysis patients, 2 of 33 health care workers and 24 of 100 persons from the control group. The highest prevalence of SENV was among hemodialysis patients, significantly higher than in the groups of health care workers, acute hepatitis B and controls. The lowest prevalence was in health care workers group, significantly lower also in comparison with groups of chronic hepatitis B and C. Among the possible risk factors of virus transmission the average duration of hemodialysis (1.15 vs. 0.50 years), number of surgeries (1.60 vs. 1.10) and transfusions (1.34 vs. 0.94) showed notable differences in terms of SENV infection. Bilirubin and aminotransferase levels did not differ between SENV-positive and -negative groups. No pathogenetic role of SEN virus in liver injury was confirmed.

SEN Virus Infection in Children in Taiwan

SEN virus (SENV) is a newly discovered DNA virus. We conducted this study to evaluate potential modes of SENV transmission and the pathogenic effect of SENV on liver diseases in children. Polymerase chain reaction was used to detect 2 SENV variant (SENV-D and SENV-H) DNA in sera from healthy individuals and diseased children. Nucleotide sequence of SENV was determined by direct sequencing. SENV infection was assessed in healthy individuals, including 50 newborns (sera collected from the umbilical cord), 24 infants, 46 preschool children (aged 1-6 years), 42 school children of an age before that of the first sexual experience (aged 7-12 years), 62 adolescents (13-18 years), 72 young adults (19-30 years) and 32 adults (>30 years). The prevalence of SENV-D and/or SENV-H (SENV-D/H) viremia in each group was 0%, 17%, 24%, 24%, 27%, 33% and 40%, respectively. The prevalence of SENV-D/H viremia in 18 children with non-A to E hepatitis, 64 thalassemic children, 80 children transfused during cardiac surgery, 30 children with chronic hepatitis B, 9 children with chronic hepatitis C and 32 infants with biliary atresia was 11%, 61%, 80%, 83%, 67% and 50%, respectively. SENV was found more frequently in all patient groups than in 174 age-matched controls (P < 0.01), with the exception of non-A to E hepatitis (11% versus 24% in the control group; P = 0.27). In 2 infants with proven intrauterine hepatitis B viral infection, identical SENV-D nucleotide sequence existed in both the maternal and neonate serum. Elevated alanine aminotransferase concentrations were rarely observed in children who acquired isolated SENV viremia because of transfusion for surgery. Infection with SENV in children with chronic hepatitis C virus or hepatitis B viral infection was not associated with higher peak alanine aminotransferase values. SENV is transmitted mainly via nonparenteral daily contact and frequently occurs early in life. Transfusion can significantly increase the rate of SENV viremia. SENV does not appear to cause hepatitis in children.

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.

SEN virus infection in patients with hepatocellular carcinoma

Although most cases of hepatocellular carcinoma (HCC) are associated with either the hepatitis B or C viruses (HBV, HCV), about 10-20% of HCCs occur in patients with chronic hepatitis that is aetiologically undefined. The aim of the present study was to determine the prevalence of the transfusion-transmitted SEN virus (SEN-V) in patients with HCC, including those patients who do not otherwise appear to be infected with HBV or HCV. Fragments of SEN-V subtypes D and H were amplified separately by PCR from the sera of 50 patients with HCC (31 from Canada and 19 from Japan) as well as from HCC and adjacent nontumourous liver tissues from eight of the Canadian patients. SEN-V DNA was found in the serum of 10 of 31 (32%) Canadian patients and eight of 19 (42%) Japanese patients [overall, 18 of 50 (36%) HCC patients]. SEN-V DNA was detected in the serum of 10 of 23 (43%) HCC patients with antibody to HCV (anti-HCV), six of 11 (55%) with hepatitis B surface antigen (HBsAg), and two of 16 (12%) without detectable anti-HCV or HBsAg. Twenty-three HCC patients in this study had 'silent HBV,' characterized by the detection of HBV DNA in the absence of HBsAg; eight of these (35%) also had SEN-V infections. SEN-V DNA was detected in HCC patients most typically in those with coexistent HBV or HCV infection. SEN-V was found in only one of seven HCC patients without HBV (without HBsAg or HBV DNA) or HCV and thus does not appear to be an important cause of 'cryptogenic' HCC.

Potential role of SEN virus on liver enzyme abnormalities in patients positive for hepatitis C virus with or without HIV infection

A novel single-stranded DNA virus named SEN virus (SENV), which was initially cloned from the plasma of an HIV-positive patient in a cohort we previously studied [1], has been observed in patients suffering from acute and chronic liver diseases of unknown etiology [2]. However, the possible role of SENV in hepatic inflammation is not clear [3]. Phylogenetic analysis of SENV has demonstrated the existence of eight subtypes (A–H), with the SENV H and D subtypes being associated with liver disease more frequently [4, 5]. The epidemiology and clinical implications of SENV infection are currently being investigated. Recently, we demonstrated a lack of negative impact of SENV on the clinical progression of HIV infection [6] and the apparent dynamism of SENV infection, with both clearance and reinfection appearing over time [7]. In HIV-infected patients, hepatitis C virus (HCV) has become a frequent cause of morbidity and mortality in the era of highly effective antiretroviral therapy, and hepatic impairment is aggravated by toxicity due to antiretroviral drugs [8]. Thus, it seems necessary to investigate whether SENV has an impact on patients coinfected with HCV and HIV with or without antiretroviral therapy. The goals of the retrospective, cross-sectional study reported here were to investigate the influence that SENV infection (subtypes A, B, D, and H) may exert on the biochemical hepatic features of patients affected by HIV and chronic HCV in the presence or absence of antiretroviral treatment. As a secondary objective, we also studied the associated charac

The prevalence of SEN virus infection in blood donors in Taiwan

ObjectivesTo determine the prevalence of SENV infections among blood donors in central Taiwan and to clarify the relationship between these infections and elevated alanine aminotransaminase (ALT) values. MethodsDNA was extracted from plasma of 200 blood donors and amplified by seminested PCR. ResultsFor all donors, the prevalence of SENV-D was 32%, and of SENV-H was 30.5%. Prevalence of mixed SENV-D/H infection was 11.5% and of SENV-D and/or SENV-H (SENV-D/H) was 51%. Infections were not associated with age, gender, or raised ALT values. ConclusionsSENV-D and SENV-H infections are common among blood donors in central Taiwan but are unlikely to contribute to abnormal ALT values.

Significance of SEN virus in post-transfusion hepatitis. Bedeutung von SEN-Viren für die Posttransfusionshepatitis

Abstract Five hepatitis viruses (A-E) cause more than 80% of cases of viral hepatitis. However, the fact that nearly 20% of individuals with acute hepatitis test negative for all known hepatitis viruses, as do up to 10% of patients with transfusion-associated hepatitis, suggests the existence of other viral hepatitis agents. Hepatitis G virus (HGV) and TT virus (TTV) were originally proposed as potential causative agents. The SEN virus (SENV) belongs to a recently discovered group of DNA viruses whose members (SENV D and SENV H) are associated with post-transfusion hepatitis. Eight different strains of SENV have been identified and provisionally classified as members of the Circoviridae family, a group of small, single-stranded, non-enveloped circular DNA viruses which includes, in addition to SENV, the TT virus (TTV), TUS01, SANBAN, PMV, and YONBAN viruses. SENV is a single-stranded circular, non-enveloped DNA virus of ~3.600 to ~3.900 nucleotides with at least three open reading frames (ORFs). The prevalence in different populations shows great variability with marked differences between different countries and groups. Although parenteral transmission is very likely, other routes of transmission are not excluded. Mother-to-infant transmission has been demonstrated. Data on other acute and chronic liver diseases are sparse. Further studies are needed to define the pathogenesis and clinical importance of SENV infection.