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Biomedical subjects

D Thouvenot

Publications and source records attributed to D Thouvenot.

At least 19 recordsLinked to original sources
PubMed2005

Herpes simplex virus thymidine kinase mutations associated with resistance to acyclovir: a site-directed mutagenesis study.

Mutations in the thymidine kinase (TK) gene of herpes simplex virus (HSV) may confer resistance to acyclovir (ACV). Because of the high genetic polymorphism of this gene, discriminating between mutations related to resistance and mutations related to gene polymorphism can be difficult, especially when no sensitive strain has been previously isolated from the same patient. To assess the role of the mutations located at codons 51, 77, 83, and 175, previously detected in HSV-1 clinical isolates (F. Morfin, G. Souillet, K. Bilger, T. Ooka, M. Aymard, and D. Thouvenot, J. Infect. Dis. 182:290-293, 2000), in the acquisition of resistance to ACV, four mutants with site-directed mutations at these respective codons were constructed. The enzymatic activity of the proteins, produced using both a reticulocyte lysate system and a bacterial system, was evaluated using [(3)H]thymidine as substrate. This site-directed mutagenesis revealed that mutations at codons 51, 83, and 175 induce a loss of HSV-1 TK activity and are thus clearly involved in the acquisition of resistance to ACV. On the other hand, the mutation at codon 77 does not affect enzyme activity.

Acyclovir↗
PubMed2004

[Nosocomial infections due to adenovirus in a paediatric unit].

OBJECTIVE: We carried out a retrospective analysis of an outbreak of adenovirus (AdV) infections in a paediatric unit. The aim of the study was to analyse cases, determine the route of transmission and to evaluate the efficacy of the prevention measures. PATIENTS AND METHODS: The study was performed by recollection of AdV infection cases during a period of 1 year and the results were compared with the list of clinical cases recorded during the epidemic. The clinical files of children with a positive specimen were retrospectively analysed. During that period, five members of the medical staff showed clinical signs and symptoms of AdV infection. A throat swab was collected from a subset of the staff. RESULTS: Among nine patients with positive AdV detection, six were infected with an Adv type 2. Six were nosocomially-acquired, the other two were only probable nosocomial infections. The index case was a child presenting a febrile diarrhoea 48 h prior to being admitted to the hospital. Nosocomial transmission was associated with the prolonged shedding of the virus with faeces of the infected cases. The specimens collected from the staff remained negative. The outcome was favourable for all children. CONCLUSIONS: Prevention measures, implemented when the epidemic was characterised, allowed the control of the nosocomial outbreak.

Adenovirus Infections, Human↗
PubMed2004

Surveillance network for herpes simplex virus resistance to antiviral drugs: 3-year follow-up.

Herpes simplex virus (HSV) infections are very common in the general population and among immunocompromised patients. Acyclovir (ACV) is an effective treatment which is widely used. We deemed it essential to conduct a wide and coordinated survey of the emergence of ACV-resistant HSV strains. We have formed a network of 15 virology laboratories which have isolated and identified, between May 1999 and April 2002, HSV type 1 (HSV-1) and HSV-2 strains among hospitalized subjects. The sensitivity of each isolate to ACV was evaluated by a colorimetric test (C. Danve, F. Morfin, D. Thouvenot, and M. Aymard, J. Virol. Methods 105:207-217, 2002). During this study, 3900 isolated strains among 3357 patients were collected; 55% of the patients were immunocompetent. Only six immunocompetent patients excreted ACV-resistant HSV strains (0.32%), including one female patient not treated with ACV who was infected primary by an ACV-resistant strain. Among the 54 immunocompromised patients from whom ACV-resistant HSV strains were isolated (3.5%), the bone marrow transplantation patients showed the highest prevalence of resistance (10.9%), whereas among patients infected by human immunodeficiency virus, the prevalence was 4.2%. In 38% of the cases, the patients who excreted the ACV-resistant strains were treated with foscarnet (PFA), and 61% of them developed resistance to PFA. The collection of a large number of isolates enabled an evaluation of the prevalence of resistance of HSV strains to antiviral drugs to be made. This prevalence has remained stable over the last 10 years, as much among immunocompetent patients as among immunocompromised patients.

Acyclovir↗
PubMed2003

Three ECHOvirus serotypes responsible for outbreak of aseptic meningitis in Rhône-Alpes region, France.

During the year 2000 in the Rhône-Alpes region of France, 559 cases of aseptic meningitis due to enterovirus infection were recorded (approximate incidence, 10 cases per 100,000 population compared with a mean of 0.3 cases during endemic years in this region; P<0.001). Cerebrospinal fluid samples were collected from all 559 patients and processed for enterovirus RNA detection using a reverse transcriptase polymerase chain reaction assay only. In addition to the cerebrospinal fluid samples, 40 stool and 76 throat samples were collected from 116 patients (20.7% of cases); the following three enterovirus serotypes were isolated from the stool and throat samples only: ECHOvirus 13 (48/116; 41.3%), ECHOvirus 30 (44/116;37.9%) and ECHOvirus 6 (24/116, 20.7%). This is the first report that demonstrates the involvement of three different ECHOvirus serotypes, particularly ECHOvirus 13, in an outbreak of aseptic meningitis, in the French Rhône-Alpes region.

Adolescent↗
PubMed2002

[Management of mucocutaneous herpes simplex virus infections in immunocompetent patients: signification and limits of antigen detection culture methods and antibody detection].

Herpes simplex virus (HSV) infections are very common and may present various manifestations. Mostly asymptomatic, often mild, these infections may become life-threatening, specially in neonates. The acute and rapid diagnosis of HSV infections can prevent infections in these patients and is also helpful to confirm clinical diagnosis. The sensitivity of "classical" diagnosis methods, such as culture and antigen detection by immunofluorescence and ELISA, is highly dependent on the quality of the sample. Antigen detection techniques give results in short delays, compatible with the initiation of antiviral treatment; however their sensitivity decreases when lesions get older and they are not convenient for the diagnosis of asymptomatic infections. Isolation of HSV on cell culture remains the gold standard, because it is easy to perform and exhibits good sensitivity whatever the stage of the lesions; the isolation of the virus is required for HSV typing and to determine susceptibility to antiviral agents in case of clinical resistance to the treatment. Serodiagnosis is helpful to determine the immune status of a patient and to distinguish between primary infection and recurrence. It is now possible to differentiate HSV1 and HSV2 antibodies; the benefit of type-specific serology is clear for epidemiological surveys but may be discussed for individual follow-up, specially for genital herpes, both for the diagnosis and the prevention of HSV infections.

Enzyme-Linked Immunosorbent Assay↗
PubMed2001

Genetic classification of "Sapporo-like viruses".

"Sapporo-like viruses" (SLVs) and "Norwalk-like viruses" (NLVs) are an important cause of acute gastroenteritis in humans. While NLVs have been genetically classified into three major genetic groups consisting of 17 genetic subgroups, a classification of SLVs into comparable genetic groups remains to be determined. In an attempt to classify both SLVs and NLVs uniformly, the sequences of 2 SLV strains newly detected from French infants were analysed together with the published sequences of 9 SLV and 19 NLV strains. Distance and phylogenetic analyses were conducted on the sequences of the capsid gene, RNA polymerase gene, 3' open reading frame (3'ORF), ORF overlapping the capsid gene, and 3' untranslated region (3'UTR). The histogram showing frequency distribution of pairwise distances and the topology of the phylogenetic tree demonstrated that SLVs and NLVs could be classified uniformly on the basis of the entire capsid sequences and that the 11 SLV strains could be genetically classified into 3 major genetic groups, genogroups I, II and III, comprised of 5 genetic subgroups. The differentiation of the 11 SLV strains into these genetic groups was also maintained in the 4 remaining genome regions, while the sequences at the junction between the RNA polymerase and capsid genes were shown to be genogroup-specific.

3' Untranslated Regions↗
PubMed2001

Development of a real-time PCR procedure including an internal control for the measurement of HCMV viral load.

Human cytomegalovirus (HCMV) infections are frequent in immuno-compromised patients. The recent development of real-time PCR procedures that allow the rapid quantification of genome load will be helpful for accurate monitoring of these infections. Two extraction procedures were evaluated using 30 blood samples that were processed pure and diluted (1/10). Repeatability and reproducibility of the quantitative PCR procedure using an internal control for amplification were analysed, and its sensitivity compared to a qualitative PCR procedure using 50 HCMV culture positive blood samples. The real-time PCR and qualitative PCR procedures were positive in 46 and 48 of the samples tested, respectively. Discrepancies were observed for samples with a low viral load. The sensitivity of the real-time PCR procedure was evaluated at 500 HCMV DNA copies per ml of sera. The use of an internal control concomitantly processed during the HCMV quantification did not alter the sensitivity of the procedure, and was relevant for the detection of putative PCR inhibitors that may interfere with the amplification process. This procedure was used to measure genome load in two bone marrow transplant patients with HCMV disease, confirming that this new PCR procedure should be used widely for diagnosing and monitoring HCMV infections in transplant patients.

Bone Marrow Transplantation↗
PubMed2001

Development of an immunoassay (ELISA) for the quantification of thiram in lettuce.

Two competitive immunoassays, a laboratory assay based on microwell plates and a field test based on the use of polystyrene tubes, have been developed for the quantification of thiram in lettuces. Concerning the laboratory assay, the calibration curve for thiram had a linear range of 11 to 90 ng/mL and a detection limit of 5 ng/mL. Precision of the assay presented coefficient of variation values <9% and the recovery of thiram from lettuce averaged 89% across the range of the immunoassay method using 30 min extraction with water/acetone (50:50, v/v). The tube-based method was developed in order that an extract of lettuce, containing thiram at the MRL (8 ppm), would be found on the linear part of the standard curve. The calibration curve for thiram has a linear range of 100 to 800 ng/mL (1.39 to 11.1 ppm in lettuce) and a detection limit of 40 ng/mL.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Resistant herpes simplex virus type 1 infection: an emerging concern after allogeneic stem cell transplantation.

Fourteen cases of severe acyclovir-resistant herpes simplex virus type 1 (HSV-1) infection, 7 of which showed resistance to foscarnet, were diagnosed among 196 allogeneic stem cell transplant recipients within a 29-month period. Recipients of unrelated stem cell transplants were at higher risk. All patients received foscarnet; 8 subsequently received cidofovir. Strains were initially foscarnet-resistant in 3 patients and secondarily so in 4 patients. In vitro resistance to acyclovir or foscarnet was associated with clinical failure of these drugs; however, in vitro susceptibility to foscarnet was associated with complete response in only 5 of 7 patients. No strain from any of the 7 patients was resistant in vitro to cidofovir; however, only 3 of 7 patients achieved complete response. Therefore, acyclovir- and/or foscarnet-resistant HSV-1 infections after allogeneic stem cell transplantation have become a concern; current strategies need to be reassessed and new strategies must be evaluated in this setting.

Acyclovir↗
PubMed2000

Genetic characterization of thymidine kinase from acyclovir-resistant and -susceptible herpes simplex virus type 1 isolated from bone marrow transplant recipients.

Emergence of acyclovir (Acy)-resistant herpes simplex virus (HSV) is a major concern in bone marrow transplant recipients. Phenotypic and genetic characterization of thymidine kinase (TK) was done for 7 Acy-susceptible and 11 Acy-resistant HSV-1 isolated from 11 patients. In total, 19 amino acid substitutions were detected that were not related to Acy resistance but to TK gene polymorphism, including 5 mutations that have not been previously reported. The Acy-resistant strain from 1 patient presented no TK gene mutation related to resistance. Five patients (45%) had isolates that harbored point mutations leading to amino acid substitutions that could be associated with Acy resistance. Of the 5 substitutions detected, 3 have not been previously reported (codons 51, 83, and 175). A nucleotide insertion or deletion was detected in resistant isolates from 5 patients (45%); these mutations are located in homopolymer repeats at codon 92 (1 subject) and at codon 146 (4 subjects).

Acyclovir↗
PubMed2000

Cytomegalovirus infection may cause ureteral necrosis.

Cytomegalovirus (CMV) infection has protean presentation among immunocompromised patients, but the urinary tract is rarely involved. We report a case of extensive ureteral necrosis in a renal transplant, 12-year-old patient with typical histological feature of CMV inclusions. The role of CMV was confirmed by immunohistochemical analysis and concomitant CMV DNA detection in peripheral blood leukocytes by polymerase chain reaction analysis. CMV infection can, therefore, be regarded as a possible cause of ureteral necrosis in renal transplant recipients.

Child↗
PubMed2000

Development of cytomegalovirus resistance to ganciclovir after oral maintenance treatment in a renal transplant recipient.

The emergence of a resistant strain is a theoretical threat after extensive use of antiviral drugs. We report the emergence of a ganciclovir-resistant cytomegalovirus (CMV) strain in a kidney transplant recipient during oral ganciclovir maintenance treatment. The patient was treated by oral ganciclovir for 2 months after successful treatment of CMV primary infection by intravenous ganciclovir. He developed a new episode of CMV infection with no clinical response to intravenous ganciclovir. The CMV isolate exhibited both phenotypic and genotypic resistance to ganciclovir. The CMV isolate was constituted of a mixture of strains, with and without a mutation at codon 460 of the UL97 gene. The clinical condition improved when mycophenolate mofetil (MMF) was discontinued, and a short course of intravenous globulin was added to ganciclovir. The emergence of the CMV strain could be secondary to more potent immunosuppression provide by MMF or subtherapeutic level obtained during oral ganciclovir treatment. We believe that ganciclovir resistance must be part of the differential diagnosis when a patient relapses or fails to respond to ganciclovir treatment.

Administration, Oral↗
PubMed2000

Diagnosis and surveillance of herpes simplex virus infection of the central nervous system.

Herpes simplex viruses (HSV) are responsible for neurological disorders that require rapid diagnostic methods and specific antiviral therapy. During 1997, 1431 cerebrospinal fluid samples (CSF) collected from 1339 patients with neurological disorder presentations were processed for HSV detection. Eleven patients were positive for HSV, seven presenting with encephalitis (6/7 due to HSV1) and 4 with aseptic meningitis (4/4 due to HSV2). The incidence of HSV encephalitis was 2.33 cases / 10(6) inhabitants/year. Among encephalitis (HSV encephalitis) cases, 1 patient died due to the late implementation of antiviral therapy, and sequelae were observed in 4 cases. No sequelae were observed in aseptic meningitis cases. Four HSV encephalitis cases were monitored by PCR detection in CSF. Despite acyclovir therapy, PCR remained positive in CSF up to 20 days in 2 cases. This result suggest that the antiviral treatment for HSV encephalitis should be monitored by PCR detection of HSV in CSF.

Acyclovir↗
PubMed2000

Hapten synthesis for the development of a competitive inhibition enzyme-immunoassay for thiram.

An enzyme-linked immunosorbent assay (ELISA) was developed for the fungicide thiram. Two types of haptens were synthesized. The first type exhibits the two symmetrical N-alkyl dithiocarbamate patterns of thiram with a spacer arm linked to one of the N-methyl terminal group. The second type exhibits one of the two symmetrical N-alkyl dithiocarbamate patterns of thiram with a variable-length spacer arm linked to one sulfur atom. Polyclonal antibodies suitable for thiram detection were obtained from immunization with an hapten of the first type, while haptens of the second type were used as coating antigens to develop a competitive ELISA against thiram. The IC(50) value for thiram was estimated to be 0.24 microg/mL, with a detection limit of 0.03 microg/mL. The assay seems to be thiram-specific since no or little cross-reaction with other dithiocarbamates were observed.

Binding, Competitive↗
PubMed2000

Acyclovir-resistant varicella infection with atypical lesions in a non-HIV leukemic infant.

UNLABELLED: An HIV-negative infant presented with VZV primary infection during the maintenance therapy for megakaryoblastic leukaemia. The lesions were initially vesicular and necrotic but became verrucous and hyperkeratotic. A clinical resistance to acyclovir was suspected and confirmed by histologic and virologic studies. The patient was successfully treated by foscarnet. CONCLUSION: resistance of VZV to acyclovir may occur after a short treatment in a non-AIDS patient.

Acyclovir↗