Epidemiological characteristics, risk factors, and clinical manifestations of acute non-A-E hepatitis

Identification of sapovirus GV.2, astrovirus VA3 and novel anelloviruses in serum from patients with acute hepatitis of unknown aetiology

Hepatitis is a general term meaning inflammation of the liver, which can be caused by a variety of viruses. However, a substantial number of cases remain with unknown aetiology. We analysed the serum of patients with clinical signs of hepatitis using a metagenomics approach to characterize their viral species composition. Four pools of patients with hepatitis without identified aetiological agents were evaluated. Additionally, one pool of patients with hepatitis E (HEV) and pools of healthy volunteers were included as controls. A high diversity of anelloviruses, including novel sequences, was found in pools from patients with hepatitis of unknown aetiology. Moreover, viruses recently associated with gastroenteritis as sapovirus GV.2 and astrovirus VA3 were also detected only in those pools. Besides, most of the HEV genome was recovered from the HEV pool. Finally, GB virus C and human endogenous retrovirus were found in the HEV and healthy pools. Our study provides an overview of the virome in serum from hepatitis patients suggesting a potential role of these viruses not previously described in cases of hepatitis. However, further epidemiologic studies are necessary to confirm their contribution to the development of hepatitis.

Exploring the potential of next-generation sequencing in detection of respiratory viruses

Efficient detection of human respiratory viral pathogens is crucial in the management of patients with acute respiratory tract infection. Sequence-independent amplification of nucleic acids combined with next-generation sequencing technology and bioinformatics analyses is a promising strategy for identifying pathogens in clinical and public health settings. It allows the characterization of hundreds of different known pathogens simultaneously and of novel pathogens that elude conventional testing. However, major hurdles for its routine use exist, including cost, turnaround time, and especially sensitivity of the assay, as the detection limit is dependent on viral load, host genetic material, and sequencing depth. To obtain insights into these aspects, we analyzed nasopharyngeal aspirates from a cohort of 81 Thai children with respiratory disease for the presence of respiratory viruses using a sequence-independent next-generation sequencing approach and routinely used diagnostic real-time reverse transcriptase PCR (real-time RT-PCR) assays. With respect to the detection of rhinovirus and human metapneumovirus, the next-generation sequencing approach was at least as sensitive as diagnostic real-time RT-PCR in this small cohort, whereas for bocavirus and enterovirus, next-generation sequencing was less sensitive than real-time RT-PCR. The advantage of the sequencing approach over real-time RT-PCR was the immediate availability of virus-typing information. Considering the development of platforms capable of generating more output data at declining costs, next-generation sequencing remains of interest for future virus diagnosis in clinical and public health settings and certainly as an additional tool when screening results from real-time RT-PCR are negative.

Case definitions for acute hepatitis C virus infection: a systematic review

BACKGROUND & AIMS

Case definitions for recent hepatitis C virus (HCV) infection vary considerably between studies. The aim of this systematic review was to characterize case definitions for recent HCV and explore the heterogeneity in studies performed to date.

METHODS

A systematic literature search of MEDLINE, SCOPUS, and ISI Web of Knowledge was performed covering all studies of recent HCV infection cited between January 2000 and June 2011. The criteria used by each study to define cases of recent HCV infection were extracted, structured, and analyzed.

RESULTS

Overall, 195 articles were included, with 87% (n=169) providing a clear case definition for recent HCV infection. The most frequently used individual criteria for defining a case included HCV antibody seroconversion (77%), alanine aminotransferase (ALT) elevation (68%), and HCV RNA detection (63%). In studies using HCV antibody seroconversion, the window period between the last negative and the first positive antibody test varied widely across studies (4 weeks to 4 years). Considerable diversity was also observed with respect to the ALT threshold used to characterize ALT elevations, ranging from 2 to 20 times the upper limit of normal. HCV antibody seroconversion was used as a single criterion in 41% of the studies, while all other studies used at least two criteria (range: 2-9). Epidemiology/surveillance studies mostly used a more sensitive case definition, whereas treatment studies, natural history studies, and diagnosis studies used more specific case definitions.

CONCLUSIONS

Marked heterogeneity in case definitions for recent HCV infection was observed. Although a single case definition for recent HCV is not warranted, a degree of standardization within specific study categories would enable improved cross-study comparison and more uniform evaluation of HCV prevention and management strategies.

Treatment of HBV/HCV coinfection

IMPORTANCE OF THE FIELD

Hepatitis B (HBV) and hepatitis C (HCV) virus infections are among the most common causes of advanced chronic liver disease worldwide. HBV/HCV coinfection is not uncommon with an estimated 7 - 20 million individuals affected worldwide. Patients with HBV/HCV coinfection have an increased risk for cirrhosis, hepatocellular carcinoma (HCC) and even death.

AREAS COVERED IN THIS REVIEW

The pathophysiology of HBV/HCV coinfection is complex, as different patterns of virological dominance may occur, which can even fluctuate over time. Recently, combination of pegylated interferon (PEG-IFN) plus ribavirin has been explored in HBV/HCV coinfected patients who are positive for HCV-RNA. HBV polymerase inhibitors may be indicated if HBV-DNA concentrations are above 2000 IU/ml. In this review, we summarize the epidemiology, viral interaction, its clinical features and the available treatment options.

WHAT THE READER WILL GAIN

Insights into viral interaction of HBV/HCV coinfection and treatment individualization strategies are provided in the review.

TAKE HOME MESSAGE

Detailed serological and virological evaluations are required for HBV/HCV coinfected patients before initiation of antiviral therapy. At present, PEG-IFN-alpha plus ribavirin should be the treatment of choice in patients with dominant HCV replication. However, HBV rebound may occur after elimination of HCV, and thus close monitoring for both viruses is recommended even for patients with initially suppressed HBV-DNA.

Human picobirnaviruses identified by molecular screening of diarrhea samples

The global threat of (re)emerging infectious viruses requires a more effective approach regarding virus surveillance and diagnostic assays, as current diagnostics are often virus species specific and not able to detect highly divergent or unknown viruses. A systematic exploration of viruses that infect humans is the key to effectively counter the potential public health threat caused by new and emerging infectious diseases. The human gut is a known reservoir of a wide variety of microorganisms, including viruses. In this study, Dutch clinical diarrhea samples for which no etiological agent could be identified by available cell culture, serological, or nucleic acid-based tests were gathered. Large-scale molecular RNA virus screening based on host nucleic acid depletion, sequence-independent amplification, and sequencing of partially purified viral RNA from a limited number of clinical diarrhea samples revealed four eukaryotic virus species. Among the detected viruses were a rhinovirus and a new picobirnavirus variant. In total, approximately 20% of clinical diarrhea samples contained human picobirnavirus sequences. The Dutch picobirnaviruses belonged to different phylogenetic clades and did not group with other picobirnaviruses according to year of isolation or host species. Interestingly, the average age of patients infected with picobirnavirus was significantly higher than that of uninfected patients. Our data show that sequence-independent amplification of partially purified viral RNA is an efficient procedure for identification of known and highly divergent new RNA viruses in clinical diarrhea samples.

Epidemiological characteristics and clinical manifestations of acute non-A-E hepatitis

Background/Aim. Acute non-A, non-B, non-C, non-D, non-E hepatitis (non-A-E AH) is an acute disease of the liver of unknown etiology for which one or more new, so far undetected, hepatotropic viruses may be responsible. The frequency of non-A-E AH ranges from 3.8% to 33.9%, and therefore it has a significant place within current infectology and hepatology. The aim of our study was to establish the frequency, clinical and biochemical characteristics, natural course and outcome of non-A-E AH and compare them with control groups affected by acute viral hepatitis A, B and C. Methods. This descriptive-analytic prospective study included 31 patients with non-A-E AH treated at the Institute of Infectious and Tropical Diseases, Clinical Center of Serbia, Belgrade, from 2003 to 2008. They were followed up during the period not less than 6 months. The controls involved randomly selected patients, treated at the same time with a definite diagnosis of acute viral hepatitis A, B and C. Statistical data analysis used Mann-Whitney Utest, Student's t-test and variance analysis. The value of p < 0.05 was considered statistically significant. Results. The frequency of non-A-E AH was 7.6%. Almost no difference was found between sexes (male/female ratio was 1 : 1.07); it was developed in all age groups, with the highest incidence in the middle age (mean age was 38.32 ? 15.3 years). It appeared equally throughout the whole year. Out of risk factors, inoculation risk was predominant (before all, dental interventions), mostly involving urban population living in comfortable conditions. The duration of incubation varied much ranging from 20 to 180 days (median 60 days). By clinical course, moderate and icteric forms were most common, mostly corresponding to acute hepatitis A and C. On the other hand, by duration of the disease (mean duration was 67.1 ? 27.1) and chronic transformation, non-A-E AH resembled to acute hepatitis B. Progression to chronicity was recorded in 9.68% of the patients. There was no fulminant neither cholestatic form of the disease. Conclusion. Based on the results obtained in this study, it is probable that there are some so far undetected primary hepatotropic viruses in our environment.

Rapid identification of known and new RNA viruses from animal tissues

Viral surveillance programs or diagnostic labs occasionally obtain infectious samples that fail to be typed by available cell culture, serological, or nucleic acid tests. Five such samples, originating from insect pools, skunk brain, human feces and sewer effluent, collected between 1955 and 1980, resulted in pathology when inoculated into suckling mice. In this study, sequence-independent amplification of partially purified viral nucleic acids and small scale shotgun sequencing was used on mouse brain and muscle tissues. A single viral agent was identified in each sample. For each virus, between 16% to 57% of the viral genome was acquired by sequencing only 42–108 plasmid inserts. Viruses derived from human feces or sewer effluent belonged to the Picornaviridae family and showed between 80% to 91% amino acid identities to known picornaviruses. The complete polyprotein sequence of one virus showed strong similarity to a simian picornavirus sequence in the provisional Sapelovirus genus. Insects and skunk derived viral sequences exhibited amino acid identities ranging from 25% to 98% to the segmented genomes of viruses within the Reoviridae family. Two isolates were highly divergent: one is potentially a new species within the orthoreovirus genus, and the other is a new species within the orbivirus genus. We demonstrate that a simple, inexpensive, and rapid metagenomics approach is effective for identifying known and highly divergent new viruses in homogenized tissues of acutely infected mice.

Viral surveillance programs aim to identify circulating viruses to safeguard the public and livestock from viral outbreaks. Occasionally, samples suspected of harboring a virus cause severe disease in laboratory animals, but the identity of the virus eludes researchers. Here, we applied a simple viral discovery technique to identify viruses directly from the tissues of inoculated symptomatic mice and found a single virus in each sample using a rapid viral particle purification and random nucleic acid amplification method. Two viruses appear to be closely related to the members of the Picornaviridae family. In three other samples, originally collected from pools of crushed mosquitoes and the brain of a sick skunk, a known and novel viruses related to members of the Reoviridiae family were identified. Reoviruses are considered major pathogens of livestock. Our studies provide the groundwork for further analysis of the prevalence and pathogenesis of these divergent viruses and illustrate the ease with which new viral species can be identified in tissues of acutely infected animals.

Quantitative assessment of serum NV-F virus DNA concentrations in samples from patients coinfected with hepatitis B or C virus

A novel hepatotropic virus, named NV-F virus, was recently identified. The clinical information for this virus is still scarce. Using PCR assay, NV-F viral DNA (NV-F-DNA) was detected in 12 of 50 (24%) hepatitis C virus (HCV)-infected patients (HCV-coinfected [HCVCI] group), 34 of 250 (13.6%) hepatitis B virus (HBV)-infected patients (HBV-coinfected [HBVCI] group), and 28 of 100 (28%) non-A-to-E (NAE) hepatitis patients. Basic clinical parameters were not significantly different among the three groups. By use of a PCR-based quantitative assay, the NV-F-DNA concentration was found to be above the detection limit (1.2 x 10(5) copies/ml) in 12/12 (100%) HCVCI patients, 14/34 (41.2%) HBVCI patients, and 4/28 (14.3%) NAE patients. The median serum NV-F-DNA concentration was 9.3 x 10(5) copies/ml in HCVCI patients, but it was below the detection limit in HBVCI and NAE patients (P values were 0.0045 and 0.0001, respectively). Stepwise multiple regression analysis identified the presence of anti-HCV as an independent factor for NV-F-DNA concentrations (beta = 6.2 x 10(9); P = 0.0245). In HBVCI patients, the NV-F-DNA concentration was inversely correlated with the HBV DNA concentration. The median NV-F-DNA concentration was below the detection limit in patients with HBV DNA concentrations above 1.4 x 10(5) copies/ml, but it was 1.58 x 10(6) copies/ml in patients with HBV DNA concentrations below 1.4 x 10(5) copies/ml (P = 0.030). In conclusion, NV-F-DNA concentrations were higher in HCVCI patients. A reciprocal relationship was found between NV-F-DNA and HBV DNA concentrations in HBVCI patients, indicating the presence of viral interference between these two DNA viruses.

Spontaneous viral clearance following acute hepatitis C infection: a systematic review of longitudinal studies

A large number of studies have reported on spontaneous viral clearance rates in acute hepatitis C infection, however most have been small, and reported rates have varied quite widely. To improve the precision of the estimated rate of spontaneous viral clearance, a systematic review was conducted of longitudinal studies. Factors associated with viral clearance were also examined. Inclusion criteria for studies were: longitudinal assessment from time of acute hepatitis C; hepatitis C virus RNA analysis as determinant of viral clearance; untreated for acute hepatitis C. Information on study population, and factors that may influence viral clearance were extracted from each study. Viral clearance was defined among individuals with at least 6 months follow-up following acute hepatitis C. The number of subjects with viral clearance was expressed as a proportion for each study and a weighted mean for proportion was calculated. A total of 31 studies were examined. Study populations included nine studies of post-transfusion hepatitis, 19 of acute clinical hepatitis, and three of sero-incident cases. In total, data was available for 675 subjects and the mean study population was 22 (range 4-67). The proportion with viral clearance ranged from 0.0 to 0.8, with a weighted mean of 0.26 (95% CI 0.22-0.29). Factors associated with viral clearance were female gender and acute clinical hepatitis C study population. Further studies are required to more clearly define predictors of clearance and guide therapeutic intervention strategies.