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H Agut

Publications and source records attributed to H Agut.

At least 55 records · Page 3Linked to original sources
PubMed1998

Mutations in NS5A region of hepatitis C virus genome correlate with presence of NS5A antibodies and response to interferon therapy for most common European hepatitis C virus genotypes.

A part of the hepatitis C virus (HCV) nonstructural protein 5A (NS5A) amino acid sequence, designated as an interferon (IFN)-sensitive determining region (ISDR), has been shown to be correlated with a response to IFN in Japanese patients. We have shown previously that the presence of NS5A antibodies (Abs) detected by the INNOLIA test (IL-NS5A Ab) is also correlated with a response to IFN. The aim of this study was to investigate, in a wide range of patients, the possible relationship within the NS5A protein between the sequence of ISDR and that used in the INNOLIA test designated as IL3R. Serum samples from 52 patients infected by HCV genotypes 1, 2, and 3 were analyzed before and after treatment. The patients were classified as nonresponders (NRs), responder-relapsers (RRs), or long-term responders (LTRs). We amplified the NS5A region for 42 patients using polymerase chain reaction (PCR), and these amplicons were sequenced directly. The 10 remaining patients were analyzed using PCR with mutation-specific primers. No correlation was found between the IL3R sequence of the HCV strains and the presence of the IL-NS5A Ab for all genotypes. However, for the subtype 1b, only 2 of 11 NR patients tested had an arginin in position 2218 within the ISDR versus 3 of 3 LTR and 10 of 13 RR patients. All patients with R-2218 had IL-NS5A Ab. For the genotype 1a, 2 of 2 LTR and 1 of 3 RR were mutated in position 2216-2218 in comparison to three NR sequences. For the genotype 3, no mutations were found in the region homologous to 1b-ISDR, but 4 of 5 LTR and RR patients had a mutation T-2161 to A or V versus 0 of 3 NR patients. A close correlation was found between arginin in position 2218 in ISDR, the presence of IL-NS5A Ab, and the response to IFN therapy for genotype 1b, but this association did not predict a long-term response. For genotype 3, a potential ISD mutation could be located at the codon 2161.

Amino Acid Sequence↗
PubMed1998

[Importance of molecular biology in retrovirus and herpesvirus infections].

Molecular biology has long been used as a tool for basic research in virology. Its medical use is recent and has been supported both by numerous technical improvements and the discovery of new human viruses. This is illustrated by the emergence of human immunodeficiency virus (HIV)-1, HIV-2, human T-cell leukemia virus (HTLV)-I/II, and human herpesviruses (HHV) 6, 7 and 8. Polymerase chain reaction (PCR) gave a major boost to an extended use of molecular biology techniques. This resulted in a better knowledge of human viral infections as illustrated by studies on HIV and HHV-8. New viruses have been characterized. Molecular markers have permitted analysis of virus transmission cases, classification of genetic variants and detection of mixed infections. The quantitation of viral load has led to a better understanding of chronic infections and reactivations. As a tool for diagnosis, molecular biology is not yet considered as a universal alternative to classical procedures such as serology and antigen detection. However, major improvements in molecular biology techniques might question current diagnosis strategies in the very near future.

HIV↗
PubMed1998

Definition and distribution analysis of glycoprotein B gene alleles of human herpesvirus 7.

As for other herpesviruses, glycoprotein B (gB) of human herpesvirus 7 (HHV-7) is believed to play a major role in virus infection and as a target of the host immunogenic response. Using nested PCR, we amplified the whole HHV-7 gB gene from 108 human peripheral blood mononuclear cell samples and studied its variability. By means of restriction fragment length polymorphism (RFLP) analysis, three distinct patterns, designated I, II, and III, were defined and detected at frequencies of 93, 5, and 2%, respectively. Determination of the nucleotide sequence allowed us to recognize five critical positions in the gB gene with six specific combinations of point changes at these positions. These combinations were gB alleles A, B, C, D, E, and F. Alleles D and E corresponded to RFLP patterns II and III, respectively, while the other four alleles corresponded to RFLP pattern I. Identical gB alleles were detected in serial samples as well as in paired samples of blood and saliva from the same individuals, except for one case. In contrast, the distribution of gB alleles differed according to the geographical origin of the human samples: C was the most frequent allele in both African and Caribbean samples, whereas F was the most frequent allele in European ones. Although none of the allele-specific nucleotide changes induced any modification at the protein level, the definition of gB alleles provided convenient viral markers for the study of both HHV-7 infections and human population genetics.

Africa↗
PubMed1998

Acyclovir-resistant varicella-zoster virus: phenotypic and genetic characterization.

A man with acquired immunodeficiency syndrome (AIDS) developed zoster of the right arm which was resistant clinically to acyclovir. Varicella-zoster virus (VZV) was cultured from a skin biopsy performed at the beginning of acyclovir therapy (isolate 1) and after its failure (isolate 2). The emergence of acyclovir resistance during treatment was investigated by developing a simple and rapid drug sensitivity assay based on the plaque reduction reference method. This late-antigen synthesis reduction assay involved serial dilutions of cell-associated virus. The 50% inhibitory concentration (IC50) of acyclovir was 16 +/- 7.5 microM for the susceptible reference strain OKA, in agreement with published data. The acyclovir IC50 increased from 6.5 microM for isolate 1 to 100 microM for isolate 2. In comparison with the sequence of isolate 1, isolate 2 had a single mutation consisting of a C to T change at position 907 of the thymidine kinase gene, which changed a glutamine codon into a stop codon at position 303 of the thymidine kinase protein. These results show the emergence of acyclovir resistance through a single previously undescribed mutation in the thymidine kinase gene, and confirm the heterogeneity of mutations inducing acyclovir resistance.

AIDS-Related Opportunistic Infections↗
PubMed1998

[Absence of HHV-8 virus detected in immature hemangiomas in infants].

INTRODUCTION: The aim of our study was to search for the presence of HHV-8 DNA sequences in Biopsy specimens from hemangioma of the infancy. MATERIAL AND METHODS: The study included 9 biopsies from hemangioma. DNA of human beta-globin gene and HHV-8 were searched for by PCR using specific primers. Amplified products were revealed after an hybridization with an internal probe digoxigenin-labelled. RESULTS: Human beta-globin gene could be detected in all samples illustrating the absence of PCR inhibitor. HHV-8 could never be detected in samples analyzed. DISCUSSION: Our study does not imply any causative role of HHV-8 in the pathogenesis of hemangioma. This result must be confirmed by serologic studies.

Biopsy↗
PubMed1997

[Kaposi disease].

Explore the source record for details and available documents.

AIDS-Related Opportunistic Infections↗
PubMed1997

[What is a virus?].

Viruses are simple biological particles, consisting of a genome, a protein capsid and, in the case of enveloped viruses, an external lipidic envelope. Owing to the presence of envelope, most enveloped viruses are fragile although some exceptions may be observed. Viruses behave as complete intracellular parasites. Their multiplication results from the replication and self-assembly of viral components, this process being directed by the viral genome after it has been released within an infected cell. Virus classification is now essentially based on molecular properties, concerning both the structure and replication strategy of viruses. In virus taxonomy, serial hierarchical levels are family, subfamily, genus and species. Within species, lower hierarchical levels are type, subtype, variant and strain. Knowledge of virus structure and classification is essential for considering the physiopathology, diagnosis and therapy of viral infections.

Humans↗
PubMed1997

Two PBMC-based neutralization assays depict low reactivity of both anti-V3 monoclonal antibodies and immune sera against HIV-1 primary isolates.

The neutralizing activity of anti-V3 monoclonal antibodies (MAbs) and anti-HIV-1 immune sera was tested against HIV-1 laboratory strains and African primary isolates. Neutralization was investigated in Phytohaemagglutinin (PHA)-stimulated peripheral blood mononuclear cell (PBMC) cultures by means of two distinct viral titer reduction assays. In these assays, virus was detected by means of either p24 antigen measurement using ELISA or HIV provirus synthesis using PCR, respectively. Anti-V3 MAbs and anti-HIV-1 immune sera neutralized efficiently the homologous laboratory HIV-1 strains used for eliciting immune response but showed no neutralizing activity against most primary isolates. The two neutralization assays used provided similar results. However, a PCR-based assay circumvented the limitations due to low levels of virus replication. The mechanism of resistance of the primary isolates to neutralizing antibodies was complex and was not simply predicted by partial sequence determination of the epitopes. This points out the need for reliable neutralization assays of HIV-1 primary isolates in order to evaluate the role of humoral immunity during HIV-1 infection and for future vaccine strategies.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Use of inverse polymerase chain reaction to characterize a novel human herpesvirus 7 isolate.

Human herpesvirus-7 (HHV-7) is a T-lymphotropic virus detected in peripheral blood mononuclear cells and in saliva, but no reliable link between this agent and a disease has been demonstrated so far. Starting from a 186 bp-fragment described previously, we used an inverse polymerase chain reaction to clone and sequence the adjacent sequences of this known region. A 1062 bp-fragment containing two ORFs was characterized and its sequence was compared with those of two other beta-herpesviruses, human cytomegalovirus (HCMV) and human herpesvirus-6 (HHV-6). With respect to the first ORF, amino-acid identity was estimated to be 22% between HHV-7 and HCMV, and 47% between HHV-7 and HHV-6. In contrast, only a weak homology between HHV-7 and the two other beta-herpesviruses was demonstrated for the second ORF. The newly characterized 1062 bp-fragment was used to define a novel HHV-7-specific PCR assay. Preliminary data indicate that this region is highly conserved among HHV-7 isolates.

Amino Acid Sequence↗
PubMed1997

Exacerbations of clinical symptoms in human immunodeficiency virus type 1-infected patients with multicentric Castleman's disease are associated with a high increase in Kaposi's sarcoma herpesvirus DNA load in peripheral blood mononuclear cells.

The epidemiologic link between multicentric Castleman's disease (MCD) and Kaposi's sarcoma (KS) and the high frequency of KS herpesvirus (KSHV) detection in both diseases raise the question of a role of this new virus in the pathogenesis of MCD. To explore this hypothesis, the KSHV DNA load was investigated in peripheral blood mononuclear cells of 3 human immunodeficiency virus (HIV)-infected patients with MCD at different points during the clinical course. Clinical parameters, such as fever and the presence of lymphadenopathy, were systematically assessed. Hemogram and C-reactive protein level determinations were performed as standard procedures. KSHV DNA load was investigated by means of semiquantitative polymerase chain reaction assay using peripheral blood mononuclear cells of the patients. A correlation between the variation in clinical and biologic parameters related to MCD and KSHV DNA load was found, suggesting a close relationship between KSHV and MCD in HIV-1-infected patients.

Castleman Disease↗
PubMed1997

Lack of evidence of human herpesvirus 8 DNA sequences in HIV-negative patients with various lymphoproliferative disorders of the skin.

Human herpesvirus 8 (HHV-8) is a new virus which has been reported in Kaposi's sarcoma and some lymphoproliferative disorders such as Castleman's disease and body-cavity-based lymphoma. Because HHV-8 shares homology with Epstein-Barr virus (EBV), we searched for the presence of HHV-8 DNA sequences in various cutaneous T- and B-cell lymphoma by the polymerase chain reaction (PCR). Forty-seven HIV-negative patients with cutaneous lymphoma or large plaque parapsoriasis were enrolled in the study. For the detection of HHV-8 DNA sequences we used PCR followed by a hybridization with a digoxigenin-labelled probe and nested-PCR. HHV-8 DNA sequences could only be detected in a patient with large plaque parapsoriasis. Our study does not suggest any direct implication of HHV-8 in the pathogenesis of most cutaneous lymphoma. Serological studies will be helpful to appreciate if there is an epidemiological link between HHV-8 and cutaneous lymphomas.

DNA, Viral↗
PubMed1997

Detection of human Betaherpesvirinae in saliva and urine from immunocompromised and immunocompetent subjects.

Human cytomegalovirus (HCMV) is a well-known opportunistic agent that reactivates in human immunodeficiency virus (HIV)-seropositive subjects. Human herpesvirus 6 (HHV-6) and HHV-7 were discovered recently and, like HCMV, belong to the Betaherpesvirinae subfamily. We looked for the presence of HCMV, HHV-6, and HHV-7 by PCR with saliva and urine samples from 125 HIV-seropositive patients at different stages of HIV infection and with saliva and urine samples from 29 HIV-seronegative subjects. All three viruses were frequently detected in the saliva (overall rates of detection, 61, 43, and 63% for HCMV, HHV-6, and HHV-7, respectively) with no correlation with the stage of immune deficiency. In contrast, HCMV was detected in urine much more frequently than the two other herpesviruses (overall rates of detection, 37, 2, and 6.5% for HCMV, HHV-6, and HHV-7, respectively) and was associated with immune deficiency. This suggests that these three genetically related viruses differ from each other with regard to replication in the urinary tract.

AIDS-Related Opportunistic Infections↗
PubMed1997

Additional mutations detected in sequential HIV-1 isolates from ZDV-treated patients.

Sequential isolates from four patients under zidovudine (ZDV) therapy were obtained using PBMC coculture in the absence or in the presence of 0.25 microM ZDV. PBMC-based HIV susceptibility assay demonstrated the emergence of ZDV-resistance in the sequential isolates from the four patients. Except in one case, the isolates obtained in the presence of ZDV did not exhibit a greater resistance pattern than their counterparts obtained in the absence of the drug. In parallel, partial reverse transcriptase gene sequence was determined directly on amplified products from proviral DNA. In addition to the mutations previously described at the critical codons 41, 67, 70, 215, and 219, numerous additional mutations were found in either ZDV-sensitive or ZDV-resistant isolates. The mutation Thr215Tyr was not observed in a case of highly resistant virus (ZDV IC50 > 6.25 microM), while the mutation Lys70Arg was found in either resistant or sensitive ones. The analysis of additional mutations did not reveal any clear pattern for ZDV resistance but pointed out the existence of highly variable regions neighbouring the five critical codons. Neither nucleotide sequence nor PBMC-based susceptibility assay provided unambiguous data about pretherapy isolates or early on-therapy isolates which could predict the emergence of ZDV resistance in further samples.

Anti-HIV Agents↗