Massimo Clementi

Active hepatitis C virus infection in bone marrow and peripheral blood mononuclear cells from patients with mixed cryoglobulinaemia

The presence of hepatitis C virus (HCV) genomic sequences was checked in plasma, liver, peripheral blood mononuclear cells (PBMC) and bone marrow cells from 11 patients with mixed cryoglobulinaemia positive for anti‐HCV antibodies, and from 11 patients with chronic HCV hepatitis without serological evidence of cryoglobulinaemia. HCV RNA sequences were demonstrated by reverse transcription polymerase chain reaction in seven plasma samples, in six PBMC samples, and in seven bone marrow cell samples from the 11 cryoglobulinaemia subjects; otherwise, viral specific nucleic acids were detected in 10 plasma samples, in one PBMC sample, and in two bone marrow cell samples from the 11 patients with chronic hepatitis. The HCV replicative intermediate was evidenced in four of the six PBMC and in five of the seven bone marrow aspirate HCV RNA‐positive samples. Analysis of subpopulations isolated from bone marrow and peripheral blood samples showed HCV RNA sequences in mononuclear ceils belonging either to the CD2+ subset or to the CDI9+ subpopulation or to the adherent cells. Finally, we compared the nucleotide sequences of a large portion (‐270 to ‐59) of the HCV 5′‐untranslated region from five patients with mixed cryoglobulinaemia and from seven patients with chronic hepatitis without cryoglobulinaemia; the degree of heterogeneity, compared with the prototype HCV sequence, was similar in both groups. These findings from two groups of HCV infected patients indicate that transient or permanent active HCV infection of bone marrow and PBMC is frequent in anti‐HCV‐positive patients with mixed cryoglobulinaemia, and suggest that extra‐hepatic infection may play a major role in influencing the pathophysiology of this infection as well as the viral persistence.

Quantitative molecular methods in virology

SummaryDuring the past few years, significant technical effort was made to develop molecular methods for the absolute quantitation of nucleic acids in biological samples. In virology, semi-quantitative and quantitative techniques of different principle, complexity, and reliability were designed, optimized, and applied in basic and clinical researches. The principal data obtained in successful pilot applications in vivo are reported in this paper and show the real usefulness of these methods to understand more details of the natural history of viral diseases and to monitor specific anti-viral treatments in real time. Theoretical considerations and practical applications indicate that the competitive polymerase chain reaction (cPCR) and competitive reverse-transcription PCR (cRT-PCR) assay systems share several advantages over other quantitative molecular methodologies, thus suggesting that these techniques are the methods of choice for the absolute quantitation of viral nucleic acids present in low amounts in biological samples. Although minor obstacles to a wide use of these quantitative methods in clinical virology still remain, further technical evolution is possible, thus making the quantitative procedures easier and apt to routine applications.

Clinical implications of GBV-C/HGV infection in patients with "HCV-related" chronic hepatitis.

BACKGROUND/AIMSnTo evaluate the clinical, biochemical and histological implications of a concomitant HGV infection in HCV-related chronic liver disease.nnnMETHODSnEighty-three HCV-RNA positive patients with chronic liver disease were tested for GBV-C/HGV coinfection by heminested PCR.nnnRESULTSnTwenty-two (26.5%) patients were found to be positive for GBV-C/HGV RNA. GBV-C/HGV+ patients differed significantly from GBV-C/HGV- ones for younger age, higher frequency of history of drug addiction, which in turn might favor coinfection with interferon-sensitive HCV genotypes (3a), and increased probability of long-term response to interferon. GBV-C/HGV infection appears to have no responsibility for specific aspects of HCV infection such as biochemical or histological cholestatic features, lymphoid follicles, symptomatic cryoglobulinemia or presence of serum autoantibodies, including LKM1. It does not worsen the HCV-related disease (ALT levels and histological activity) and does not significantly interfere with HCV infection, as explored by the number of hepatocytes positive for HCV antigens. The amount of steatosis (mean score) was shown to be higher in GBV-C/HGV+ patients. A virological follow up was performed in 17 interferon-treated GBV-C/HGV+ patients On the whole, GBV-C/HGV seems to be as sensitive to IFN treatment as HCV, but recurrence after withdrawal is more frequent. In spite of this, ALT levels often remain normal after treatment withdrawal.nnnCONCLUSIONSnThe present data suggest that GBV-C/HGV infection, apart from more marked liver steatosis, does not modify the overall picture of chronic hepatitis due to HCV infection.

Human monoclonal recombinant Fabs specific for HCV antigens obtained by repertoire cloning in phage display combinatorial vectors

Molecular cloning of the antibody repertoire in phage display combinatorial vectors is a powerful method enabling the dissection of the immunoresponse against a given pathogen. In this paper we describe the construction of a combinatorial library displayed on phage surface, containing the antibody repertoire of a patient with high serological response against hepatitis C virus (HCV) antigens. Following selection of the library against solid-phase-bound antigen, sixteen human antibody Fab fragments able to bind to HCV-specific antigens were generated and studied for binding characteristics. The majority of them appeared to have specificity for the HCV c33 peptide. All the clones reacting with the c33 peptide shared the same heavy-chain CDR3 sequence. This is the first report of molecular cloning in a combinatorial phage display vector of the antibody repertoire of an anti-HCV-positive patient.

Identification of two distinct subsets of long-term nonprogressors with divergent viral activity by stromal-derived factor 1 chemokine gene polymorphism analysis.

Stromal-derived factor (SDF)-1, the natural ligand for CXCR4, is present in a common polymorphic variant defined by a G-->A transition in the 3 untranslated region of the gene. In persons infected with human immunodeficiency virus type 1 (HIV-1), the homozygous genotype (SDF1-3A/3A) has been postulated to interfere with the appearance of T-tropic syncytium-inducing strains. The polymorphism of SDF1 was correlated with HIV-1 phenotype, plasma viremia, and unspliced and multiply spliced specific transcripts in 158 virologically characterized HIV-1-infected patients (39 recent seroconverters, 75 typical progressors, and 44 AIDS patients) and in 42 HIV-1-infected long-term nonprogressors (LTNPs). Analysis of SDF1 allele distribution revealed that SDF1-3A/3A status is associated with low CD4 cell count (P=.0449) but not with a specific HIV-1 phenotype. In LTNPs, SDF1-+/+ condition defined a subset of persons with lower HIV-1 replication than in heterozygous subjects. The low viral activity in SDF1-+/+ LTNPs suggests that other factors play a major role in vivo in determining the course of HIV-1 infection.

A vector for the expression of recombinant monoclonal Fab fragments in bacteria

The availability of genes coding for monoclonal Fab fragments of a desired specificity permits their expression in bacteria and provides a simple method for the generation of good quality reagents. In this paper we describe a new phagemid vector for the production of recombinant Fabs from genes obtained from phage display combinatorial libraries. The phagemid features an antibiotic resistance cassette which, once inserted between the heavy chain fragment and the light chain genes, avoids unwanted recombination and preserves useful restriction sites not affecting the Fab production rate.

Quantitative liver parameters of HCV infection: relation to HCV genotypes, viremia and response to interferon treatment

BACKGROUND/AIMSnThis study aimed to evaluate the relation between the number of hepatocytes positive for HCV antigens and the amount of HCV RNA in the liver and to evaluate the relationship between the above parameters and viremia levels, HCV genotype and response to interferon treatment.nnnMETHODSnThis was a retrospective study on 31 consecutive patients with chronic HCV-related liver disease, selected on the basis of the availability of frozen liver tissue for both liver HCV antigens detection and liver HCV RNA quantitation. HCV antigens (immunohistochemistry), liver and plasma HCV RNA (competitive RT-PCR), and HCV genotype (commercial kit) were studied.nnnRESULTSnA significant correlation (p=0.0005) was found between the amount of liver HCV RNA (log 10 copy/microg of extracted RNA) and the number of HCV-infected hepatocytes (scored from 0 to 3). These parameters were not significantly correlated with viremia levels. The highest liver HCV RNA levels and HCV antigen scores were found in patients infected with genotype 1b. Liver HCV RNA (median 541 x 10(3) vs 118 x 10(3) copy number/microg, p=0.031) and liver HCV antigens (mean score 2.3 vs 1.3, p=0.018) but not plasma HCV RNA (median 14956 x 10(3) vs 2885 [correction of 2.885] x 10(3) copy number/ml, ns) were significantly higher in patients not responding to interferon treatment compared to responders.nnnCONCLUSIONSnThe tissue parameters tested in this study were significantly correlated, shared the same clinical implications and predicted short-term response to interferon treatment better than viremia levels. We suggest that these tests should be included in the study protocol of patients under evaluation for interferon treatment, basing the choice on local facilities.

Are HLA class II and immunoglobulin constant region genes involved in the pathogenesis of mixed cryoglobulinemia type II after hepatitis C virus infection

BACKGROUND/AIMSnHepatitis C virus infection is known to play an important role in the pathogenesis of essential mixed cryoglobulinemia type II. Progression of hepatitis C virus infection to mixed cryoglobulinemia may be influenced by host immune response. To analyze the immunogenetic background of mixed cryoglobulinemia, we studied HLA-DR, DQ loci and the switch regions of immunoglobulin heavy chain gamma1 and gamma4 constant genes.nnnMETHODSnHLA typing was performed in 84 hepatitis C virus-infected patients (46 with cryoglobulins and 38 without), and 109 healthy controls, through analysis of restriction fragment length polymorphisms, supplemented with other techniques. Immunoglobulin heavy chain gamma1 and gamma4 polymorphisms, detected by restriction fragment length polymorphisms, were studied in 41 patients with mixed cryoglobulinemia and 51 controls.nnnRESULTSnThe gene frequency of DRB1*11 was significantly higher in patients with mixed cryoglobulinemia than in controls (0.36 and 0.20, respectively; p= 0.0035). However, DRB1*11 was also increased in the subgroup of patients without mixed cryoglobulinemia who did not develop severe liver disease, while it was decreased in those with severe liver damage (0.50 and 0.13; p=0.0035). The frequency of 5.4 kb allele of the immunoglobulin heavy chain gamma1 switch region was higher in patients with mixed cryoglobulinemia than in controls (0.47 and 0.22; pc=0.002), while the frequency of 5.5 kb allele was lower (0.51 and 0.78; pc= 0.001).nnnCONCLUSIONSnSusceptibility to develop cryoglobulins after hepatitis C virus infection was not associated with HLA-DR or DQ. HLA-DRB1*11-positive individuals were protected from serious chronic liver disease after hepatitis C virus infection. Immunoglobulin heavy chain constant gamma1 switch region restriction fragment length polymorphisms were associated with mixed cryoglobulinemia.

Dynamics of hepatitis C viremia after plasma exchange

BACKGROUND/AIMSnThe dynamics of hepatitis C viremia after perturbation by plasma exchange was addressed in two infected patients with symptomatic cryoglobulinemia. This approach may offer an alternative to studying patients treated with antivirals in order to understand the dynamics of hepatitis C virion exchange among different compartments in vivo.nnnMETHODSnPlasma exchange sessions were conducted every 24 h for 3 consecutive days; hepatitis C virus RNA copy numbers were evaluated in sequential plasma samples collected before (-24, -12, -8, and 0 h) and at short intervals (at 1, 3, 6, and 12 h) after each session.nnnRESULTSnAfter each plasma exchange session viremia dropped by 45.3-93.3% in patient 1, and by 60.5-72.7% in patient 2, paralleling (or, in some cases, exceeding) the amount of fluid exchanged. No mobilization of cell-free hepatitis C virus from extra-vascular sites was documented during the 2-h plasma exchange. The dynamics of hepatitis C viremia after each procedure was also evaluated. Pre-plasma exchange levels were restored within 3-6 h in both patients, and the mean doubling times of residual viremia were 4.6 h and 4.5 h for patients 1 and 2, respectively.nnnCONCLUSIONSnThe results, in agreement with recent evidence indicating that the turnover of hepatitis C virions is a highly dynamic process, extend previous evaluations by documenting that large amounts of newly-produced virions are introduced into the vascular compartment within a few hours of the drop in hepatitis C viremia caused by plasma exchange.

Quantitation of hepatitis C virus RNA production in two human bone marrow-derived B-cell lines infected in vitro

The ability of hepatitis C virus (HCV) to replicate in two B-cell lines, CE and TOFE, derived from bone marrow of healthy subjects was compared using qualitative and quantitative molecular methods. The presence of intracellular negative-stranded HCV RNA (replicative intermediate) was investigated by nested polymerase chain reaction (PCR) in the infected cultures at different times after infection. The amounts of positive-stranded HCV RNA (genomic RNA copies) synthesized and released from cells one week after in vitro infection were determined by competitive PCR after reverse transcription of viral RNA for the 5 viral untranslated region. In both cell lines, HCV RNA replication took place, but the TOFE cell line appeared to be a more efficient virus producer than the CE cell line. The TOFE cell line could be a valuable and reliable tool for basic and clinical HCV studies.