Interspousal transmission of GB virus-C/hepatitis G virus: A comparison with hepatitis C virus

Deep sequencing for the detection of virus-like sequences in the brains of patients with multiple sclerosis: detection of GBV-C in human brain

Multiple sclerosis (MS) is a demyelinating disease of unknown origin that affects the central nervous system of an estimated 400,000 Americans. GBV-C or hepatitis G is a flavivirus that is found in the serum of 1–2% of blood donors. It was originally associated with hepatitis, but is now believed to be a relatively non-pathogenic lymphotropic virus. Fifty frozen specimens from the brains of deceased persons affected by MS were obtained along with 15 normal control brain specimens. RNA was extracted and ribosomal RNAs were depleted before sequencing on the Illumina GAII. These 36 bp reads were compared with a non-redundant database derived from the 600,000+ viral sequences in GenBank organized into 4080 taxa. An individual read successfully aligned to the viral database was considered to be a “hit”. Normalized MS specimen hit rates for each viral taxon were compared to the distribution of hits in the normal controls. Seventeen MS and 11 control brain extracts were sequenced, yielding 4–10 million sequences (“reads”) each. Over-representation of sequence from at least one of 12 viral taxa was observed in 7 of the 17 MS samples. Sequences resembling other viruses previously implicated in the pathogenesis of MS were not significantly enriched in any of the diseased brain specimens. Sequences from GB virus C (GBV-C), a flavivirus not previously isolated from brain, were enriched in one of the MS samples. GBV-C in this brain specimen was confirmed by specific amplification in this single MS brain specimen, but not in the 30 other MS brain samples available. The entire 9.4 kb sequence of this GBV-C isolate is reported here. This study shows the feasibility of deep sequencing for the detection of occult viral infections in the brains of deceased persons with MS. The first isolation of GBV-C from human brain is reported here.

High prevalence of GBV-C/HGV among relatives of GBV-C/HGV-positive blood donors in blood recipients and in patients with aplastic anemia

BACKGROUND

The prevalence of GB virus C (GBV-C)/HGV is high in individuals with parenteral risk factors. The frequency of GBV-C/HGV in blood donors is significantly lower, however it is still far above other parenterally transmitted viruses like HBV and HCV. Therefore, transmission routes apart from parenteral transmission must be considered.

STUDY DESIGN AND METHODS

The purpose of the study was to evaluate the prevalence of GBV-C/HGV in blood donors and relatives of GBV-C/HGV-positive and -negative blood donors. Prevalence was also analyzed in aplastic anemia patients. Samples were tested by RT-PCR and partially by ELISA. Positive isolates were sequenced and phylogenetically analyzed.

RESULTS

A total of 5733 blood donors were PCR tested and 90 were positive (1.6%). Of these, 98 relatives could be tested. Viremia was found in 14.3 percent and anti-E2 in 29.5 percent, whereas only 1.1 percent of the relatives of PCR-negative donors were viremic and 8.5 percent were anti-E2 positive. Probable virus transmission could be shown in two couples and in six mother-child pairs by sequencing of isolates indicating horizontal and vertical virus transmission, respectively. Recipients of GBV-C/HGV RNA-positive blood products were shown to be infected at a rate of 58 percent (18/31). Aplastic anemia patients were positive at a rate of 32 percent (17/53).

CONCLUSION

The high percentage of 14.3 percent of GBV-C/HGV PCR-positive relatives of GBV-C/HGV-positive blood donors suggests intrafamilial transmission. Sequence analyses revealed vertical and horizontal transmission. Although parenteral transmission is highly efficient for GBV-C/HGV (58% of recipients of GBV-C/HGV RNA-positive blood products and 32% of aplastic anemia patients), it appears that sexual and vertical transmission are the most common transmission routes.

GB virus C epidemiology in Denmark: different routes of transmission in children and low- and high-risk adults

With the demonstration of an effect of GBV-C infection on the outcome of HIV infection, it has become important to understand the epidemiology of GBV-C. The purpose of this study was to determine the prevalence in high- and low-risk populations. The following populations were tested: school children, 9 and 15 years of age (n = 901), blood donors (n = 5,203), hospital employees (n = 1,432), and prisoners and injecting drug users (n = 447). In-house RT-PCR for GBV-CRNA was used together with a commercial ELISA for anti-E2 (Boehringer, Germany). In addition, questionnaires for risk factors for transmission and serological tests for HIV and hepatitis were applied. The overall prevalence of GBV-CRNA was 1.4% among children, 2.2% among blood donors, 2.2% among hospital employees, 12.5% among non-injecting prisoners, and 34.9% among drug injectors. Correspondingly anti-E2 was found in 0.3%, 12.3%, 25.0%, and 42.7%. Among hospital employees, independent risk factors for GBV-C were professions with blood exposure and sexual risk partners. Among prisoners and drug users, injecting and a sexual risk index were associated independently with GBV-C. Based on these results, the following hypothesis is suggested: GBV-C is transmitted frequently at birth or early childhood and this leads to chronic infection in most cases. Sexual transmission is the most important route of transmission in the adult population but this infection is usually transient. Blood borne transmission plays a role among health care workers and injecting drug users and GBV-C should be further evaluated as a surrogate marker for professional blood exposure.

Prevalence of hepatitis G virus in patients with hemophilia and their steady female sexual partners

BACKGROUND

Hepatitis G virus (HGV), also known as GB virus C, is a newly discovered Flavivirus that is transmissible by blood transfusion and other possible routes.

OBJECTIVE

To study the risk of sexual transmission of HGV in female sexual partners of men with hemophilia (n = 161 couples).

METHODS

Blood samples obtained from 11 medical centers were analyzed for (1) HGV RNA by polymerase chain reaction; (2) antibodies to HGV by enzyme immunoassay; and (3) other viruses and T-cell counts by routine laboratory tests. Subjects completed a questionnaire that assessed sexual intercourse frequency, number of sexual partners, condom usage, sexually transmitted diseases, illicit drug usage, and needlestick or broken-glass injuries.

RESULTS

The HGV infection (RNA +/- antibody positive) prevalence was 48% among men and 21% among women. Prevalence of hepatitis C virus, hepatitis B virus, and HIV among men was 99%, 94%, and 86%, compared with 3%, 11%, and 12% among women, respectively. The odds ratio for HGV infection for women with an HGV-positive male sexual partner was 2.14 (P = 0.06) without adjustment, and 2.77 (P = 0.03) with adjustment for other variables, none of which were independently significant.

CONCLUSION

These results suggest a low level of HGV sexual transmission.

GB virus-C/hepatitis G virus infection in Taiwan: a virus that fails to cause a disease?

Recently, an RNA virus designated GB virus-C or hepatitis G virus (GBV-C/HGV) was identified; however, its clinical significance remains uncertain. This discovery prompted us to investigate the virological, epidemiological and clinical implications of GBV-C/HGV infection in Taiwan where chronic liver diseases and liver cancer are endemic. Our results showed that genetic heterogeneity of GBV-C/HGV isolates exists, and primers from the highly conserved 5' untranslated region of viral genome can efficiently detect GBV-C/HGV RNA. Epidemiological surveys showed that GBV-C/HGV infection is common in high-risk groups in Taiwan, and its coinfection does not aggravate the course of chronic hepatitis B or C. A prospective study of transfusion-transmitted GBV-C/HGV infection also showed GBV-C/HGV does not cause classic hepatitis in most patients. In addition, GBV-C/HGV plays a minimal role in causing fulminant hepatitis. Like hepatitis C virus, sexual transmission of GBV-C/HGV exists. The risk increases with prolonged duration of exposure. In addition, high-titered maternal viremia and mode of delivery are associated with the mother-to-infant transmission of GBV-C/HGV. Interestingly, we found that GBV-C/HGV exerts no suppression on levels of chronic hepatitis B or hepatitis C viremia, and GBV-C/HGV responds to interferon; however, ribavirin plus interferon does not induce a higher sustained response. As to the replication sites of GBV-C/HGV, our preliminary results showed liver and peripheral blood mononuclear cells are not the major sites for GBV-C/HGV replication, and thus GBV-C/HGV is not a primary hepatotropic virus. In conclusion, transfusion and exchange of body fluids indeed can transmit GBV-C/HGV; however, current lines of evidence suggest that GBV-C/HGV fails to cause a disease.

Diversity of GB virus C/hepatitis G virus isolates in Singapore: predominance of group 2a and the Asian group 3 variant

The occurrence of GBV-C/HGV infection was studied in 160 individuals from two high-risk groups in Singapore. RT-PCR of the 5'-UTR detected GBV-C/HGV RNA in 3/73 (4.1%) of patients undergoing maintenance hemodialysis for chronic renal failure, and in 17/87 (19.5%) of patients coinfected with HCV who tested positive for HCV RNA. Phylogenetic analysis of 5'-UTR sequences from these 20 samples showed that the Asian or group 3 variant was found in 45% of the samples sequenced, thus confirming the high frequency of this variant in the region. Group 2a variants accounted for 50% of the samples with a complete absence of group 2b. Our analysis also provided strong bootstrap support for the subdivision of group 2 into subgroups 2a and 2b. This study shows that isolates belonging to all three main groups of GBV-C/ HGV can be detected in Singapore, with the large majority belonging to groups 2a (50%) and 3 (45%). Only a single group 1-like sequence was detected within the 20 isolates. Of interest also is that all group 3 isolates were identified in Chinese patients while group 2a was found in both Chinese and Malay.

High prevalence of GB virus C in Brazil and molecular evidence for intrafamilial transmission

The prevalence of GB virus C (GBV-C) in candidate Brazilian blood donors with normal and elevated alanine aminotransferase levels was found to be 5.2% (5 of 95) and 6.5% (5 of 76), respectively. Among Brazilian patients, GBV-C was found in 9.5% (13 of 137) of cases of hepatitis not caused by hepatitis A virus (HAV), HBV, HCV, HDV, or HEV (non-A-E hepatitis) and in 18.2% (8 of 44) of individuals infected with HCV. Molecular characterization of GBV-C by partial sequencing of the NS3 region showed clustering between members of a single family, implying intrafamilial transmission. In conclusion, these results together suggest that contagion mechanisms which facilitate intrafamilial transmission of GBV-C may partially explain the high prevalence of viremic carriers worldwide.

High prevalence of GB-C/hepatitis G virus in a Brazilian population with helminth infection

A study of GB-C virus/Hepatitis G virus (GBV-C/ HGV) infection was carried out in a rural population of Northeastern Brazil, in which the prevalence of schistosomiasis is 80-90%. Despite the absence of parenteral risk exposure, the prevalence of GBV-C/HGV markers of infection was found to be unusually increased: viremia, 16.4%; specific antibody, 18.3%. It is therefore suspected that helminth infection influenced the immune response to GBV-C/HGV infection by shifting the balance of cytokine responses from Th1 to Th2, resulting in a delayed viral clearance. Phylogenetic analysis of viral isolates did not provide evidence for high rates of sexual or mother-to-infant viral transmission. The study revealed that viral strains belonged to types 1 and 2 only (predominant in Africa and Europe, respectively), suggesting that GBV-C/HGV was introduced into the New World by white conquerors and black slaves since the 16th century.

Prevalence and genotypes of GB virus C/hepatitis G virus (GBV-C/HGV) and hepatitis C virus among patients infected with human immunodeficiency virus: evidence of GBV-C/HGV sexual transmission

The development of new antiretroviral agents may improve survival of HIV-infected individuals, and therefore chronic viral hepatitis may become more relevant in these patients. The presence of GBV-C/HGV and hepatitis C virus (HCV) RNA were investigated by reverse transcriptase-nested polymerase chain reaction in plasma from 168 Spanish HIV-infected patients belonging to four different risk groups: intravenous drug users (IVDUs), hemophiliacs, homosexuals, and heterosexuals. GBV-C/HGV-RNA and HCV-RNA were detected in 18% and 43% of the patients, respectively. The prevalence of current infection with these viruses was notably high, 19% for GBV-C/HGV and 69% for HCV, among individuals with parenteral risk of infection (intravenous drug abusers and hemophiliacs), but sexual transmission with GBV-C/HGV was also suggested because 16.5% of patients with sexual risk, either homosexual or heterosexual, had GBV-C/HGV-RNA in plasma. Although investigation of GBV-C/HGV-RNA possibly underestimates the actual prevalence of infection with GBV-C/HGV, the above data suggest that sexual contact may play a relevant role in the spread of this virus. Phylogenetic analysis showed no evidence for clustering of NS3 sequences into different genotypes or subtypes of GBV-C/HGV.