Mother-to-infant transmission occurs more frequently with GB virus C than hepatitis C virus

Discovery of a Novel Simian Pegivirus in Common Marmosets (Callithrix jacchus) with Lymphocytic Enterocolitis

From 2010 to 2015, 73 common marmosets (Callithrix jacchus) housed at the Wisconsin National Primate Research Center (WNPRC) were diagnosed postmortem with lymphocytic enterocolitis. We used unbiased deep-sequencing to screen the blood of deceased enterocolitis-positive marmosets for viruses. In five out of eight common marmosets with lymphocytic enterocolitis, we discovered a novel pegivirus not present in ten matched, clinically normal controls. The novel virus, which we named Southwest bike trail virus (SOBV), is most closely related (68% nucleotide identity) to a strain of simian pegivirus A isolated from a three-striped night monkey (Aotus trivirgatus). We screened 146 living WNPRC common marmosets for SOBV, finding an overall prevalence of 34% (50/146). Over four years, 85 of these 146 animals died or were euthanized. Histological examination revealed 27 SOBV-positive marmosets from this cohort had lymphocytic enterocolitis, compared to 42 SOBV-negative marmosets, indicating no association between SOBV and disease in this cohort (p = 0.0798). We also detected SOBV in two of 33 (6%) clinically normal marmosets screened during transfer from the New England Primate Research Center, suggesting SOBV could be exerting confounding influences on comparisons of common marmoset studies from multiple colonies.

Prevalence of human pegivirus-1 and sequence variability of its E2 glycoprotein estimated from screening donors of fetal stem cell-containing material

Background

Human pegivirus-1 (HPgV-1) is a member of the Flaviviridae family whose genomic organization and mode of cellular entry is similar to that of hepatitis C virus (HCV). The E2 glycoprotein of HPgV-1 is the principle mediator in the virus-cell interaction and as such harbors most of HPgV-1’s antigenic determinants. HPgV-1 persists in blood cell precursors which are increasingly used for cell therapy.

Methods

We studied HPgV-1 prevalence in a large cohort of females donating fetal tissues for clinical use. PCR was used for screening and estimation of viral load in viremic plasma and fetal samples. Sequence analysis was performed for portions of the 5′-untranslated and E2 regions of HPgV-1 purified from donor plasmas. Sequencing was followed by phylogenetic analysis.

Results

HPgV-1 was revealed in 13.7% of plasmas, 5.0% of fetal tissues, 5.4% of chorions, exceeding the prevalence of HCV in these types of samples. Transmission of HPgV-1 occurred in 25.8% of traceable mother-chorion-fetal tissues triads. For HPgV-1-positive donors, a high viral load in plasma appears to be a prerequisite for transmission. However, about one third of fetal samples acquired infection from non-viremic individuals. Sequencing of 5′-untranslated region placed most HPgV-1 samples to genotype 2a. At the same time, a portion of E2 sequence provided a much weaker support for this grouping apparently due to a higher variability. Polymorphisms were detected in important structural and antigenic motifs of E2.

Conclusion

HPgV-1 is efficiently transmitted to fetus at early embryonic stages. A high variability in E2 may pose a risk of generation of pathogenic subtypes. Although HPgV-1 is considered benign and no longer tested mandatorily in blood banks, the virus may have adversary effects at target niches if delivered with infected graft upon cell transplantation. This argues for the necessity of HPgV-1 testing of cell samples aimed for clinical use.

Tropism of human pegivirus (formerly known as GB virus C/hepatitis G virus) and host immunomodulation: insights into a highly successful viral infection

Human pegivirus (HPgV; originally called GB virus C/hepatitis G virus) is an RNA virus within the genus Pegivirus of the family Flaviviridae that commonly causes persistent infection. Worldwide, ~750 million people are actively infected (viraemic) and an estimated 0.75-1.5 billion people have evidence of prior HPgV infection. No causal association between HPgV and disease has been identified; however, several studies described a beneficial relationship between persistent HPgV infection and survival in individuals infected with human immunodeficiency virus. The beneficial effect appeared to be related to a reduction in host immune activation. HPgV replicates well in vivo (mean plasma viral loads typically >1×107 genome copies ml-1); however, the virus grows poorly in vitro and systems to study this virus are limited. Consequently, mechanisms of viral persistence and host immune modulation remain poorly characterized, and the primary permissive cell type(s) has not yet been identified. HPgV RNA is found in liver, spleen, bone marrow and PBMCs, including T- and B-lymphocytes, NK-cells, and monocytes, although the mechanism of cell-to-cell transmission is unclear. HPgV RNA is also present in serum microvesicles with properties of exosomes. These microvesicles are able to transmit viral RNA to PBMCs in vitro, resulting in productive infection. This review summarizes existing data on HPgV cellular tropism and the effect of HPgV on immune activation in various PBMCs, and discusses how this may influence viral persistence. We conclude that an increased understanding of HPgV replication and immune modulation may provide insights into persistent RNA viral infection of humans.

GB Virus C (GBV-C) Infection in Hepatitis C Virus (HCV) Seropositive Women with or at Risk for HIV Infection

Background

GB virus C (GBV-C) may have a beneficial impact on HIV disease progression; however, the epidemiologic characteristics of this virus are not well characterized. Behavioral factors and gender may lead to differential rates of GBV-C infection; yet, studies have rarely addressed GBV-C infections in women or racial/ethnic minorities. Therefore, we evaluated GBV-C RNA prevalence and genotype distribution in a large prospective study of high-risk women in the US.

Results

438 hepatitis C virus (HCV) seropositive women, including 306 HIV-infected and 132 HIV-uninfected women, from the HIV Epidemiologic Research Study were evaluated for GBV-C RNA. 347 (79.2%) women were GBV-C RNA negative, while 91 (20.8%) were GBV-C RNA positive. GBV-C positive women were younger than GBV-C negative women. Among 306 HIV-infected women, 70 (22.9%) women were HIV/GBV-C co-infected. Among HIV-infected women, the only significant difference between GBV-negative and GBV-positive women was age (mean 38.4 vs. 35.1 years; p<0.001). Median baseline CD4 cell counts and plasma HIV RNA levels were similar. The GBV-C genotypes were 1 (n = 31; 44.3%), 2 (n = 36; 51.4%), and 3 (n = 3; 4.3%). The distribution of GBV-C genotypes in co-infected women differed significantly by race/ethnicity. However, median CD4 cell counts and log₁₀ HIV RNA levels did not differ by GBV-C genotype. GBV-C incidence was 2.7% over a median follow-up of 2.9 (IQR: 1.5, 4.9) years, while GBV-C clearance was 35.7% over a median follow-up of 2.44 (1.4, 3.5) years. 4 women switched genotypes.

Conclusions

Age, injection drug use, a history of sex for money or drugs, and number of recent male sex partners were associated with GBV-C infection among all women in this analysis. However, CD4 cell count and HIV viral load of HIV/HCV/GBV-C co-infected women were not different although race was associated with GBV-C genotype.

GB virus C genotype 1 is rarely transmitted vertically but acquired during infancy in West Africa

Paired Ghanaian plasma and cord blood from pregnant women, alongside plasma samples from children aged 1 day to 70 months, were tested for GBV-C, HIV-1 RNA loads and anti-E2. Frequency of GBV-C vertical transmission in West Africa is significantly lower than in Europe, the USA or East Asia where genotype 2 or 3 is prevalent. While horizontal transmission appears predominant in West Africa, the lower viral load of African genotype 1 might explain limited vertical transmission.

GB virus C/hepatitis G virus

GB virus C (GBV-C), or hepatitis G virus (HGV), is a recently discovered enveloped RNA virus belonging to the Flaviviridae family. GBV-C/HGV is transmitted by contaminated blood and/or blood products, intravenous drug use, from mother to child, sexually, and possibly through close social contacts. Several reports indicate a high prevalence of GBV-C/HGV viremia (1-4%) within healthy populations in Europe and North America, and an even higher prevalence (10-33%) among residents in South America and Africa. GBV-C/HGV has been suggested to be a causative agent for non-A-non-E hepatitis. However, several contradictory observations suggest that its ability to cause hepatitis is questionable. Taken together most data suggest that GBV-C/HGV is not a major cause of liver disease despite recent data indicating that it may infect and replicate in hepatocytes.

Mother-to-infant transmission of GB virus type C/HGV

BACKGROUND

The potentially hepatotropic flavivirus-like virus, GB virus type C (GBV-C)/HGV, has been detected in a few patients with acute and chronic hepatitis and in a certain proportion of blood donors and recipients of blood or blood components.

STUDY DESIGN AND METHODS

Sera from 2979 pregnant Japanese women were examined for the presence of GBV-C/HGV RNA by nested RT-PCR. Mothers who were positive for viral RNA and their 34 infants were followed and tested for infection.

RESULTS

Of the 2979 women, 32 (1.1%) were positive for GBV-C/HGV RNA. Twenty-six (76.5%) of 34 babies born to these women were positive for the virus when first tested. A significantly higher titer of viral RNA was observed in mothers whose infants were infected than in those whose infants were uninfected (mean +/- SD, 10(6.3 +/- 0.9) vs. 10(4.6 +/- 0.9)/mL; p<0.001). Twenty-three (96%) of 24 babies born to mothers whose serum viral titers were 10(6) mL or more were infected with the virus. Infants delivered by elective caesarean section had a lower risk (OR, 0.13; 95% CI, 0.02-0.82) than those delivered vaginally or by emergency caesarean section. No other risk factors for mother-to-infant transmission were confirmed.

CONCLUSIONS

GBV-C/HGV is frequently transmitted from mothers to infants in the general population. The most critical factor is the titer of viral RNA in the maternal serum. By the use of elective caesarean section in women with high titers of viral RNA, vertical transmission of the virus may be lessened.

High rate of GB virus type C/HGV transmission from mother to infant: possible implications for the prevalence of infection in blood donors

BACKGROUND

Because GB virus type C(GBV-C)/HGV (GBV-C/HGV) is blood-borne and sexually transmitted, persons at risk of infection with such viruses have a high prevalence of GBV-C/HGV markers. However, adults with no apparent risk factors, such as blood donors, frequently are positive for GBV-C/HGV markers. Mother-to-infant transmission could explain this high prevalence, but it has been studied only through small series of GBV-C/HGV-infected mothers co-infected with HCV or HIV.

STUDY DESIGN AND METHODS

To determine the rate of mother-to-infant transmission of GBV-C/HGV RNA in women who are HCV- or HIV-negative, a prospective study was performed in a cohort of 288 mothers screened for viral RNA and in the infants born to GBV-C/HGV-infected mothers.

RESULTS

Thirteen mothers (4.5%) were found positive for GBV-C/HGV RNA. Of the infants in whom at least one blood sample was collected between the third and the ninth months of life, 89 percent were positive for viral RNA. The majority of these newborns were negative for GBV-C/HGV RNA at birth and positive after the third month. The viral RNA titers of infants born to GBV-C/HGV-infected mothers appeared as elevated as those of their mothers. All the GBV-C/HGV-infected infants remained positive for viral RNA during the entire study period. No clinical events possibly linked to a primary GBV-C/HGV infection were reported in infants. Serum ALT level and blood count remained within normal values throughout the follow-up of all GBV-C/HGV-infected infants.

CONCLUSION

The frequency of mother-to-infant GBV-C/HGV transmission is elevated and could explain the high prevalence of GBV-C/HGV markers (viral RNA and E2 antibody) in adults at low risk for blood-borne or sexually transmitted viruses, such as blood donors.

The prevalence of serum GB virus C/hepatitis G virus RNA and anti-E2 in Japanese children without a history of blood transfusion

The prevalence of serum GB virus C (GBV-C)/Hepatitis G virus (HGV) RNA and anti-E2 was investigated in Japanese children younger than 16 years of age without a history of blood transfusion and the family members of serum GBV-C/HGV RNA-positive children. The prevalences of serum GBV-C/HGV RNA and anti-E2 were 0.5% (5/1000) and 0% (0/330), respectively. Viral RNA was also detected in the mothers of all five GBV-C/HGV RNA-positive children and in two of their siblings. Sequence determinations indicated the likelihood of mother-to-infant transmission in all cases. The presence of the virus persisted for at least 10-18 months in all 5 children, without any appearance of anti-E2.

Hepatitis G virus: relevance to oral health care

OBJECTIVE

To review the current literature on the hepatitis G virus (HGV) infection, with particular attention to the aspects of interest for the dental staff.

MATERIAL AND METHODS

The authors searched for original research and review articles on specific aspects of the HGV infection including virology, epidemiology, transmission, natural history, and dental zaspects of HGV infection. The relevant articles were evaluated and reviewed.

RESULTS

HGV is a parenterally transmitted RNA virus that may cause acute, chronic, and fulminant liver disease; however, the real pathogenic potential of this virus and its possible effect on other hepatitic infections is still to be clarified. Preliminary studies have failed to demonstrate strong relationships between HGV infection and any oral disease. At present, data on the prevalence of HGV infection among health care workers are scarce. Nevertheless, in view of the potential transmission rates of HGV and the lack of effective immunization, HGV should be regarded as a potential occupational hazard for medical and dental staff.

CONCLUSION

Many virological, medical, and oral aspects of HGV infection need to be further investigated; nevertheless, until related data are available, HGV should be considered to be an infection that may be transmitted during dental care.

Partial nucleotide sequencing of the NS3/helicase region of hepatitis G virus to prove vertical transmission

To study non-parental transmission of hepatitis G virus and/or GB virus C (HGV/GBV-C), we sequenced and compared the NS3/helicase region of the virus for five HGV/GBV-C RNA-positive mothers and their 11 children who had experienced neither blood transfusion nor overt hepatitis and were negative for HBV, HCV and HIV, except in one mother coinfected with HCV. The nucleotide sequences of the familial HGV/GBV-C isolates showed high similarity of 99-100% (mean 99.8%, 100% at the deduced amino acid level) between mother and her child(ren) in each family. These findings strongly suggest the spontaneous occurrence of mother-to-child transmission of HGV/GBV-C as reported previously. They also suggest that nucleotide sequence analysis on the NS3/helicase region of HGV/GBV-C may be a useful tool to study HGV/GBV-C transmission.

High prevalence of GB virus C/hepatitis G virus RNA in patients infected with human immunodeficiency virus

Prevalence of GBV-C/HGV was determined in a cohort of HIV-infected patients, via a reverse transcription-polymerase chain reaction detection of RNA in serum, amplifying the NS5 region of GBV-C/HGV genome. GBV-C/HGV RNA was detected in 143 (37.7%) of 379 patients, with similar results in the different HIV risk groups: 25/56 (44.6%) in intravenous drug users, 66/161 (41%) in homo- and bisexual men, 35/108 (32.4%) in heterosexual patients, 6/20 (30%) in transfusion recipients (P=0.41). There was no difference according to the presence or absence of hepatitis C virus infection. In univariate analysis, GBV-C/HGV genome prevalence was lower in patients over 50 years old (18.2%), compared to other age groups (20-29 years: 34.2%; 30-39 years: 44.3%; 40-49 years: 36.7%, P=0.03), as well as in patients with normal CD4 cell count (29.2% vs. 45.4% between 200-500/mm3, and 35.3% below 200 CD4/mm3, P=0.012) and individuals with a chronic hepatitis B. However, in the multivariate analysis, the only prognostic factor of GBV-C/HGV RNA positivity was the presence of a chronic hepatitis B, compared to the absence of any HBV marker, or a previous exposition to HBV (presence of anti-HBc and/or anti-HBs, absence of HBsAg), or the presence of anti-HBs alone.