[Is GB virus C alias "hepatitis" G virus involved in human pathology?]

Phylogenetic analysis of human pegivirus from anti-hepatitis C virus IgG- positive patients

Human pegivirus type 1 (HPgV-1) is a non-pathogenic RNA virus in the Flaviviridae family that usually occurs as a co-infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), though some evidence suggests it may play a role in certain cancers. The present study aimed to determine the prevalence of HPgV-1 infection in Iraqi anti-HCV IgG-positive patients, the risk factors associated with this infection, and the genotype of local isolates of this virus. A total of 88 anti-HCV IgG-positive patients participated in this cross-sectional study. Viral RAN was extracted from whole blood samples, and cDNA was produced using reverse transcriptase-polymerase chain reaction (RT-PCR). Two pairs of primers were used in nested PCR to amplify the virus genome's 5'-untranslated region (5'UTR). For direct sequencing, fourteen PCR products from the second round of PCR were chosen at random. A homology search was performed using the basic local alignment search tool (BLAST) program to identify the resultant sequencing. The phylogenetic tree of the local isolates and 31 reference isolates was constructed using MEGA X software to estimate the virus's genetic diversity and relatedness. Out of 88 patients included in this study, 27(30.68%) of patients were found to be positive for HPgV-1 RNA. The nucleotide homology between the 14 local isolates and the reference isolates. was found to be 87-97%. Phylogenetic analysis results in a tree with four main parts, which are distributed as follows: 10 local isolates are genotype 2; 2 are genotype 1; 1 is genotype 5, and 1 is genotype 6. We conclude that when compared to other countries, the infection rate of Iraqi anti-HCV IgG-positive patients with HPgV-1 is relatively high (30.68%). The most common HPgV-1 genotype in Iraq is genotype 2.

Viral Surveillance in Serum Samples From Patients With Acute Liver Failure By Metagenomic Next-Generation Sequencing

BACKGROUND

Twelve percent of all acute liver failure (ALF) cases are of unknown origin, often termed indeterminate. A previously unrecognized hepatotropic virus has been suspected as a potential etiologic agent.

METHODS

We compared the performance of metagenomic next-generation sequencing (mNGS) with confirmatory nucleic acid testing (NAT) to routine clinical diagnostic testing in detection of known or novel viruses associated with ALF. Serum samples from 204 adult ALF patients collected from 1998 to 2010 as part of a nationwide registry were analyzed. One hundred eighty-seven patients (92%) were classified as indeterminate, while the remaining 17 patients (8%) served as controls, with infections by either hepatitis A virus or hepatitis B virus (HBV), or a noninfectious cause for their ALF.

RESULTS

Eight cases of infection from previously unrecognized viral pathogens were detected by mNGS (4 cases of herpes simplex virus type 1, including 1 case of coinfection with HBV, and 1 case each of HBV, parvovirus B19, cytomegalovirus, and human herpesvirus 7). Several missed dual or triple infections were also identified, and assembled viral genomes provided additional information on genotyping and drug resistance mutations. Importantly, no sequences corresponding to novel viruses were detected.

CONCLUSIONS

These results suggest that ALF patients should be screened for the presence of uncommon viruses and coinfections, and that most cases of indeterminate ALF in the United States do not appear to be caused by novel viral pathogens. In the future, mNGS testing may be useful for comprehensive diagnosis of viruses associated with ALF, or to exclude infectious etiologies.

Genotype Distribution and Prevalence of Human Pegivirus among High-Risk Populations in Tunisia

OBJECTIVE

A recently discovered non-A-E hepatitis virus has been designated as human Pegivirus (HPgV). HPgV is prevalent in high-risk groups such as patients with hepatitis C virus (HCV), and it is of interest for patients who are at risk for transmitted infections. The aim of this study was to evaluate the prevalence of HPgV as well as the genotype distribution among patients in the Tunisian population who are infected with HCV and also in multitransfused patients.

METHODS

A total of 144 patients were screened using RTPCR/nested PCR of the 5'-untranslated region (UTR); 14 cases were sequenced and phylogenetically analyzed.

RESULTS

Seven (14.9%) subjects from the multitransfused group and 7 (7.2%) patients infected with HCV, respectively, were found positive for HPgV RNA. Sequencing and phylogenetic analysis of the 14 cases revealed that genotype 2a was the main genotype circulating in Tunisian patients. Genotype 2b was found in the amplified samples of 2 HCV-infected patients.

CONCLUSION

This study enriches the limited data on HPgV prevalence in Tunisia, and shows, for the first time, the molecular epidemiology of the circulating strains in this country.

Viral metagenomics

Characterisation of new viruses is often hindered by difficulties in amplifying them in cell culture, limited antigenic/serological cross-reactivity or the lack of nucleic acid hybridisation to known viral sequences. Numerous molecular methods have been used to genetically characterise new viruses without prior in vitro replication or the use of virus-specific reagents. In the recent metagenomic studies viral particles from uncultured environmental and clinical samples have been purified and their nucleic acids randomly amplified prior to subcloning and sequencing. Already known and novel viruses were then identified by comparing their translated sequence to those of viral proteins in public sequence databases. Metagenomic approaches to viral characterisation have been applied to seawater, near shore sediments, faeces, serum, plasma and respiratory secretions and have broadened the range of known viral diversity. Selection of samples with high viral loads, purification of viral particles, removal of cellular nucleic acids, efficient sequence-independent amplification of viral RNA and DNA, recognisable sequence similarities to known viral sequences and deep sampling of the nucleic acid populations through large scale sequencing can all improve the yield of new viruses. This review lists some of the animal viruses recently identified using sequence-independent methods, current laboratory and bioinformatics methods, together with their limitations and potential improvements. Viral metagenomic approaches provide novel opportunities to generate an unbiased characterisation of the viral populations in various organisms and environments.

New DNA viruses identified in patients with acute viral infection syndrome

A sequence-independent PCR amplification method was used to identify viral nucleic acids in the plasma samples of 25 individuals presenting with symptoms of acute viral infection following high-risk behavior for human immunodeficiency virus type 1 transmission. GB virus C/hepatitis G virus was identified in three individuals and hepatitis B virus in one individual. Three previously undescribed DNA viruses were also detected, a parvovirus and two viruses related to TT virus (TTV). Nucleic acids in human plasma that were distantly related to bacterial sequences or with no detectable similarities to known sequences were also found. Nearly complete viral genome sequencing and phylogenetic analysis confirmed the presence of a new parvovirus distinct from known human and animal parvoviruses and of two related TTV-like viruses highly divergent from both the TTV and TTV-like minivirus groups. The detection of two previously undescribed viral species in a small group of individuals presenting acute viral syndrome with unknown etiology indicates that a rich yield of new human viruses may be readily identifiable using simple methods of sequence-independent nucleic acid amplification and limited sequencing.