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Biomedical subjects

H Agut

Publications and source records attributed to H Agut.

133 records · Page 8Linked to original sources

Detection of human cytomegalovirus DNA in liver biopsies from patients with cytomegalovirus-related liver disease.

Infection with human cytomegalovirus (HCMV) has been associated with severe diseases in immunologically impaired patients. Cytomegalovirus hepatitis has been frequently described in this population, but this diagnosis is still difficult. Molecular hybridization with the V EcoRI restriction fragment of human cytomegalovirus strain AD 169 has been tested upon DNA extracted from liver samples to assess the usefulness of this technique for cytomegalovirus hepatitis diagnosis. This probe was shown by the Southern technique not to hybridize with DNA extracted from cells infected with other herpesviruses or with DNA of non-infected normal liver. The sensitivity was estimated to be 2 x 10(5) genomes. Twenty-five renal transplant recipients under immunosuppressive therapy and three patients having the acquired immunodeficiency syndrome were studied. In 9 out of 10 renal transplant recipients with normal liver, previous exposure to cytomegalovirus, as defined by serological tests, was not sufficient to allow positive detection by the probe. Out of 11 patients with abnormal liver, cytomegalovirus DNA sequences were shown in 5. In 2 patients with histological evidence of cytomegalovirus hepatitis, a very strong signal showed the presence of viral genomes. These results show that the Southern technique with the V EcoRI probe can be useful for the diagnosis of HCMV hepatitis and might be proposed for the detection of this viral genome in human tissues.

Acquired Immunodeficiency Syndrome↗

Mutations in the human immunodeficiency virus type 1 reverse transcriptase gene observed in stavudine and didanosine strains obtained by in vitro passages.

We have selected a human immunodeficiency virus type 1 (HIV1) using the technique of in vitro selection to generate variants that are resistant to didanosine and/or stavudine. After serial passages of the Lai strain of HIV1 in MT-2 cells in increased concentrations of didanosine-stavudine association, 2 novel mutations in reverse transcriptase at codon 57 (Asp-->His) and at codon 98 (AIa-->Val) were observed. These mutations were associated with an 11.5-fold increase in the didanosine and a 4.5-fold increase in the stavudine 50% inhibitory concentration.

Anti-HIV Agents↗

Selection and characterization of two specific monoclonal antibodies directed against the two variants of human herpesvirus-6.

Monoclonal antibodies (mAbs) specific for human herpesvirus-6 (HHV6) proteins were derived from the splenocytes of mice immunized with HHV6 TAN isolate-infected peripheral blood mononuclear cells. The two mAbs 8C8 and 7C7 reacted by means of immunofluorescence and immunoperoxidase assays with both variant A and variant B isolates giving two different staining patterns. In infected cells, cytoplasmic diffuse staining was observed with mAb 8C8, whereas intense nuclear staining was obtained with mAb 7C7. These different locations of viral target proteins were confirmed by confocal microscopy. The mAb 8C8 reacted with a family of six glycoproteins designated as the gp72 complex in the case of variant A strains and gp63 complex in the case of variant B strains. The endoglycosidases H and F reduced those glycoproteins to a putative precursor molecule of 58 kDa. The mAb 7C7 reacted with 116 and 109 kDa proteins with the two HHV6 variants. These two mAbs did not neutralize virion infectivity in the absence of complement. No cross-reactivity was observed when these mAbs were used in immunoperoxidase assay and immunoblotting against the proteins of human cytomegalovirus or other human herpesviruses. Thus, the two mAbs 8C8 and 7C7 may be valuable tools for the diagnosis and biological investigation of HHV6 infections.

Animals↗

Detection of antibodies to human herpesvirus-6 using immunofluorescence assay.

A serological study of human herpesvirus-6 (HHV-6) infection was performed by means of immunofluorescence assay on fixed HHV-6-infected cells. Comparison between indirect immunofluorescence assay (IFA) and anticomplement immunofluorescence assay (ACIF) showed that the latter test was the most appropriate for HHV-6 serology, although both methods exhibited identical sensitivity. ACIF, which was performed on HSB2 cells infected with the HBLV strain (provided by S.Z. Salahuddin), was then used to determine the titre of HHV-6 antibodies in serum by end-point dilution. The sera from 115 healthy subjects and 99 patients with presumed viral infection were tested. A similar distribution of HHV-6 titres was evidenced in both cases and the rate of individuals exhibiting a positive titre of 20 and above was about 30% of the whole population studied. No serological cross-reactivity was observed between HHV-6 and other herpesviruses, suggesting that the HHV-6 ACIF test was quite specific.

Adult↗

[Human herpesvirus-6 infection and hepatitis following heart transplantation].

OBJECTIVES: Human Herpesvirus-6 (HHV-6) has been implicated in hepatitis and HHV-6 infections have been reported in patients receiving heart transplants. We investigated the occurrence of such infections and their possible relation with post-transplantation hepatitis in 58 heart transplanted patients. METHODS: The titre of HHV-6 antibodies was determined by anticomplement immunofluorescence assay and compared with the titre of CMV antibodies determined by using ELISA. RESULTS: HHV-6 seroprevalence after transplantation did not differ significantly between hepatitis, control patients (without hepatitis) and the healthy general population. In three controls and five hepatitis patients we observed, after transplantation, a seroconversion or a significant increase of antibody titre which suggested active HHV-6 infection. In six cases, HHV-6-specific IgM were found whereas CMV-specific IgM were not detected. CONCLUSION: These results indicate that HHV-6 infection is frequent after heart transplantation but not in relation with hepatitis. The mechanism of this infection needs to be clarified (either primo-infection or reactivation) and the question remains whether this infection is totally asymptomatic or could induce serious illness.

Antibodies, Viral↗

[The discovery of three novel human viruses, human herpesviruses 6, 7, and 8].

Three novel human herpesviruses have been discovered in the last years: human herpesvirus 6 (HHV-6) in 1986, human herpesvirus 7 (HHV-7) in 1990, human herpesvirus 8 (HHV-8) in 1994. HHV-6 and HHV-7 were identified after their isolation from blood lymphocyte cultures, while HHV-8 was first detected by means of a specific molecular biology approach in the search for the etiologic agent of Kaposi's sarcoma. The three viruses infect lymphocytes, T-cells in the case of HHV-6 and HHV-7, B-cells in the case of HHV-8. Human infection with HHV-6 and HHV-7 is ubiquitous and widespread while HHV-8 infection seems to be more restricted, at least in Western countries. The propagation in cell culture in vitro can be done easily with HHV-6, with more difficulties in the case of HHV-7 and has not been completely obtained in the case of HHV-8. The polymerase chain reaction is the common method for the detection of these three viruses in human samples. The oncogenic role of HHV-6 and HHV-7 which were both classified in Betaherpesvirinae subfamily has not been convincingly demonstrated. HHV-8, classified as a member of Gammaherpesvirinae subfamily, is strongly associated with three lymphoproliferative diseases: Kaposi's sarcoma, Castleman's disease and primary effusion lymphomas.

Herpesviridae Infections↗