Genetic variability of German hepatitis C virus isolates

Noninvasive assessment of hepatic fibrosis in Egyptian patients with chronic hepatitis C virus infection

AIM: To evaluate the accuracy of specific biochemical markers for the assessment of hepatic fibrosis in patients with chronic hepatitis C virus (HCV) infection.

METHODS: One hundred and fifty-four patients with chronic HCV infection were included in this study; 124 patients were non-cirrhotic, and 30 were cirrhotic. The following measurements were obtained in all patients: serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin, total bilirubin, prothrombin time and concentration, complete blood count, hepatitis B surface antigen (HBsAg), HCVAb, HCV-RNA by quantitative polymerase chain reaction, abdominal ultrasound and ultrasonic-guided liver biopsy. The following ratios, scores and indices were calculated and compared with the results of the histopathological examination: AST/ALT ratio (AAR), age platelet index (API), AST to platelet ratio index (APRI), cirrhosis discriminating score (CDS), Pohl score, Göteborg University Cirrhosis Index (GUCI).

RESULTS: AAR, APRI, API and GUCI demonstrated good diagnostic accuracy of liver cirrhosis (80.5%, 79.2%, 76.6% and 80.5%, respectively); P values were: < 0.01, < 0.05, < 0.001 and < 0.001, respectively. Among the studied parameters, AAR and GUCI gave the highest diagnostic accuracy (80.5%) with cutoff values of 1.2 and 1.5, respectively. APRI, API and GUCI were significantly correlated with the stage of fibrosis (P < 0.001) and the grade of activity (P < 0.001, < 0.001 and < 0.005, respectively), while CDS only correlated significantly with the stage of fibrosis (P < 0.001) and not with the degree of activity (P > 0.05). In addition, we found significant correlations for the AAR, APRI, API, GUCI and Pohl score between the non-cirrhotic (F0, F1, F2, F3) and cirrhotic (F4) groups (P values: < 0.001, < 0.05, < 0.001, < 0.001 and < 0.005, respectively; CDS did not demonstrate significant correlation (P > 0.05).

CONCLUSION: The use of AAR, APRI, API, GUCI and Pohl score measurements may decrease the need for liver biopsies in diagnosing cirrhosis, especially in Egypt, where resources are limited.

Pathomorphological Characteristics and Pathogenesis of Viral Hepatitis

Viral hepatitis (VH) is an inflammatory reaction of the liver to hepatotropic viruses. Acute VH can be classified according to the virus and type of necrosis. Chronic hepatitis (CH) might be active, persistent or lobular based on previous classification. More recently the grade (necroinflammatory activity) and stage (fibrosis and architectural distorsion) of CH have been distinguished and scored. Apoptosis and necrosis probably coexist in VH and contribute to hepatocyte death. Several "death factors", such as transforming growth factor b, Apo1/Fas and tumor necrosis factor play a role in the execution of cell death. Injury of hepatocytes during viral infection can occur as a direct effect of the virus or as a result of the host immune response. Expression of different viral antigens can be detected during VH and might be visualized. Phenotyping of the portal inflammatory cell infiltrate in CH has shown a T-cell zone comprised of CD4+ helper T cells and CD8+ supressor/cytotoxic T cells at the periphery of the lobules. The pathogenetic mechanisms responsible for the final outcome of viral infection depend on viral factors (such as genotype, mutation etc.), virus-host interaction, expression of viral protein, several cytokines etc. which finally lead to the well known histological alterations of viral hepatitis.

Competition among Sclerotinia sclerotiorum genotypes within canola stems

Populations of Sclerotinia sclerotiorum are often composed of multiple genotypes. In examining 35 naturally infected canola plants, 29 supported reproduction (i.e., sclerotium formation) by a single S. sclerotiorum genotype, as defined by the mycelial compatibility test. Only six plants supported reproduction by two genotypes. To test the hypothesis that infrequent multiple genotype infections were due to differences in virulence or competitive ability among isolates, four greenhouse experiments were conducted in which four isolates, representing three genotypes, were used in pairwise coinoculations of canola. There were no differences among the isolates in four virulence parameters. Mean reduction in sclerotial mass produced by a coinoculated isolate was calculated by comparison with the mean sclerotial mass of that isolate in the absence of competition, and used as the measure of competition. In all experiments, at least half of the coinoculation treatments resulted in reduced fungal reproduction for one or both of the coinoculated isolates, providing evidence of competitive differences. Generally, the magnitude of reproduction reduction was the same for each isolate in the pair. However, the magnitude was nonreciprocal when the more competitive isolate was given an advantage of early temporal arrival or spatial placement of inoculum at the lower position on the stem. Competitive differences among S. sclerotiorum isolates affecting reproduction represent one possible mechanism to explain temporal shifts in genotype frequencies. Key words: canola, competition, population structure, Sclerotinia sclerotiorum, virulence.

Hepatitis C virus genotypes in the liver and serum of patients with chronic hepatitis C

OBJECTIVE: To evaluate the prevalence of hepatitis C virus (HCV) genotypes in a central area of Italy (Umbria); to analyze the correspondence of the genotypes detected in serum and liver samples; to study the relationship between HCV genotypes and severity of liver disease; to test whether co-infection with more than one HCV subtype could be influenced by the source of infection. METHODS: Genotyping by polymerase chain reaction with core-specific primers (Okamoto method) was performed in the serum and liver from 48 consecutive patients with histologically confirmed chronic C hepatitis. RESULTS: HCV genotype 1b was the prevalent strain and was not associated with more severe histologic damage. Data show a very good correspondence between genotypes identified in serum and liver specimens (91%). Mixed infections (with subtypes 1b and 2a) correlated significantly with intravenous drug abuse (p=0.001). CONCLUSION: We confirmed that subtype 1b is prevalent in central Italy. Co-infection with more than one subtype is not rare in intravenous drug abusers.

Genomic characterization of hepatitis C virus isolates from Argentina

Thirty-three Argentinian patients infected with hepatitis C virus (HCV) were studied for viral genotyping. The patients included 10 hemophiliac and 4 polytransfused children and 19 adults: 3 polytransfused, 7 dialyzed and 9 sporadic cases. Core-based genotyping permitted the classification of 31 samples. Genotypes II, I and V were the most frequent: 21 (63.6%), 16 (48.4%) and 10 (30.3%) of the 33 patients, respectively. Only one polytransfused patient carried genotype IV. Genotype II was detected in 7 out of 9 sporadic cases. Thirteen patients (39.3%) were coinfected with two genotypes, and 2 others were coinfected with three genotypes. The remaining 2 samples which could not be typed were characterized following the restriction fragment length polymorphism (RFLP) method, and were classified as type 1. One of these had two consecutive transitional mutations in the 5' untranslated region (5' UTR).

Occurrence of antibodies reactive with more than one variant of the putative envelope glycoprotein (gp70) hypervariable region 1 in viremic hepatitis C virus-infected patients

The hepatitis C virus (HCV) is a frequent cause of chronic liver disease. A mechanism proposed as being responsible for virus persistence is evasion of the host immune response through a high mutation rate in crucial regions of the viral genome. We have sequenced the hypervariable region 1 (HVR1) of the virus isolated from three serum samples, collected during 18 months of follow-up, from an asymptomatic HCV-infected patient. A synthetic peptide of 27 amino acids, corresponding to the HVR1 sequence found to be predominant in both the second and third samples, was used as the antigen for detection of antibodies by enzyme-linked immunosorbent assay (ELISA). We observed reactivity against this HVR1 sequence in the first serum sample before the appearance of the viral isolate in the bloodstream; the reactivity increased in the second and third samples while the cognate viral sequence became predominant. Moreover, our results show that antibodies from all three samples recognize a region mapping at the carboxyl-terminal part of the HVR1 and are cross-reactive with the HVR1 sequence previously found in the same patient. The presence of anti-HVR1 antibodies was investigated in a further 142 HCV patients: 121 viremic and 21 nonviremic. Two synthetic peptides were used, the first corresponding to the sequence derived from the patient described above and the second one synthesized according to the sequence of the HCV BK strain. A high frequency of positive reactions against both HVR1 variants was detected in the samples from the viremic individuals. Finally, antibodies cross-reactive with both variants were shown to be present by competitive ELISA in 6 of 10 viremic patients. The potential negative implications of this observation for the host are discussed.

Host and viral features in chronic HCV infection: relevance to interferon responsiveness

Host and viral variables interact in determining the course and responsiveness to therapy of any viral infection. Presence of cirrhosis, serum levels of hepatitis C virus (HCV) RNA and the genotype of infecting virus are considered predictive of response to interferon (IFN) in chronic HCV infection. We evaluated these parameters in relation to IFN therapy in a cohort of anti-HCV-positive subjects with chronic hepatitis or cirrhosis. HCV RNA was detected by polymerase chain reaction (PCR) and by the branched DNA assay (bDNA), to quantify viraemia. HCV typing was performed by reverse-hybridization line probe assay. HCV RNA was detected in almost all anti-HCV-positive subjects with liver disease, PCR being more sensitive than bDNA. Hepatitis C viraemia was lowest in cirrhosis. Low pretreatment viraemia selected for those patients with chronic hepatitis obtaining a high rate of sustained response to IFN. The role of HCV type was less clearcut, due to the high prevalence in our population of type 1 (especially subtype 1b, accounting for 80% of cases). A trend towards a better response of non-1b genotypes was confirmed. This may be related to higher HCV RNA levels in type 1b-infected subjects. Cirrhosis remains however, independently from virological features, the strongest predictor of non-response to IFN.

Genotypes and virus load in patients with hepatitis C infection

Virus load was tested by means of PCR calibrated with standards and HCV genotypes were determined by the LIPA-technique using sera from 123 HCV patients. Of these 39 were on renal hemodialysis treatment, 19 suffered from hemophilia, 13 were i.v. drug users and the remaining 52 had none of these risk factors (chronic hepatitis group). The most prevalent subtype in Austria was 1b followed by 3a and 1a. However, genotype 1b infections were found relatively less often in hemophilia patients and drug users than in the other groups, indicating that hemophiliacs probably had been infected by an antihemophilic plasma coming from South American or Asian donors. The highest amounts of virus were found in patients infected with genotype 3a. Determination of the patient's virus load and of the infecting subtype of HCV may be helpful in planning interferon alpha therapy.

Nucleotide-specific PCR for molecular virus typing

Nucleotide sequence studies detected a double-point mutation in the genomic RNA segment 4 (nt 871 and 872) of the persistent variant C/AA-pi of influenza C/Ann Arbor/1/50 virus. The 3'-end-points of two distinct PCR primers were positioned exactly at this genome location and thereby adjusted the priming determinant complementary to the varied strain or to its wild-type counterpart. Consequently, positive RT-PCR products strictly referred to one of the two viruses examined, in both cases, using either virion or infected-cell RNA templates. Artificial virus mixtures could easily be distinguished by this method in a subsequent qualitative gel analysis. PCR annealing conditions and control reactions were optimized, for the monitoring of influenza virus isolates throughout multifold passages. Thus, sequence diversity in just two neighbouring nucleotides is sufficient to determine whether or not successful PCR amplification takes place, and this method can be used as a reliable means of virus strain differentiation.

Analysing the sequence diversity of the 5' NC-region of HCV-isolates found in southern Germany

In this study we compared the nucleotide sequence of the 5' NC-region of the HCV genome isolated from seven patients and two blood donors from Southern Germany. We could identify two very distinct groups of isolates: the first very similar to the HCV prototype sequence (HCV1) with homology ranging from 99.5% to 98.7%; the second showing 91.7% homology to the HCV1. Group 1 isolates could be found in five patients and the two blood donors. Group 2 isolates could be found in the two other patients. Finally, we could observe neither nucleotide insertion nor deletion in the isolates described here.

Hepatitis C virus (HCV) genotype distribution in German isolates: studies on the sequence variability in the E2 and NS5 region

We report on molecular characterization of hepatitis C virus (HCV) isolates in intravenous drug abusers, as compared to non-drug using patients with posttransfusion hepatitis or sporadic hepatitis of unknown origin. Virus typing was performed by RFLP analysis of PCR products in the 5' NCR. Subtyping was done by hybridization with subtype specific probes or by sequencing in the NS4 and NS5 region, respectively. HCV subtype 1b was found most commonly among all the isolates. However, the subtype 3a had a high prevalence (about 46%) in the group of drug addicts. In these subtype 3a isolates the N-terminal part of the E2 protein was highly variable. This confirms the presence of a hypervariable region (HVR1) in this envelope protein found in all hepatitis C viruses. Each subtype 3a isolate examined had a characteristic unique hypervariable region in the E2 protein. It is noteworthy that there are four amino acids in this region which were highly conserved between all HCV sequences published. It can be assumed that such conserved amino acids are significant for structure and function of this viral protein. In our HCV subtype 3a isolates the NS5 sequences were highly conserved.

Genotyping of Canadian hepatitis C virus isolates by PCR

We used PCR for hepatitis C virus (HCV) genotyping with type-specific primers from the core and NS5 genes. Type I was predominant in the general population (58% in blood donors) as well as in different risk groups, such as intravenous drug abusers (58%), blood transfusion recipients (64%), hemophiliacs (62%), and patients with HCV chronic liver disease (76%). Types II, III, and IV were less prevalent in Canada, being found in 10.92, 6.72, and 5.88% of the population, respectively. The type II core primer was not type specific and reacted with the majority of our type I HCV samples, suggesting a false-positive dual infection with two different genotypes (I and II). Digestion of these amplified type I and type II products with restriction endonuclease AccI proved to be very useful in the exclusion of false-positive dual type I and type II infections.