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Biomedical subjects

M Aymard

Publications and source records attributed to M Aymard.

At least 109 records · Page 6Linked to original sources
PubMed1990

Specific detection of enteroviruses in clinical samples by molecular hybridization using poliovirus subgenomic riboprobes.

Enteroviruses were specifically detected in crude clinical specimens or in cell cultures in which the viruses were amplified by dot hybridization by using poliovirus type 1-derived, subgenomic radiolabeled cRNA probes (riboprobes). The sensitivity of this test varied from 2.5 to 33%, when clinical specimens without cell culture were examined, and was about 85% in cell culture lysates. The specificity of the test was 90 to 100%. The riboprobe corresponding to the 5'-noncoding sequence specifically detected the majority of enteroviruses (56 of 57 tested); the riboprobe derived from the VPI capsid region hybridized with the three poliovirus serotypes and with some coxsackieviruses type A and with echovirus type 7. Echovirus 22 did not hybridize with any riboprobe. In stool specimens, nasal aspirates, and cerebrospinal fluids from patients with meningitis, only one type of virus was identified in different clinical samples from the same patient by the seroneutralization test. Hybridization allowed the detection of enteroviral RNAs easily in stool specimens and nasal aspirates but with a low efficiency in cerebrospinal fluids without amplification of the viruses in cell cultures.

Capsid↗
PubMed1990

A new C1q solid-phase assay for the detection of IgM immune complexes: application to the follow-up of kidney graft recipients with recurrent cytomegalovirus infection.

A C1q solid-phase enzyme assay for detecting circulating immune complexes (CIC) containing immunoglobulins M was developed. IgM immune complexes (IgM-CIC) bind to purified C1q-coated microplates. The amount of bound IgM-CIC is determined by adding anti-mu-alkaline phosphatase conjugate. This assay proved IgM-CIC specific; it does not detect IgG-CIC nor free anti-CMV IgM. Furthermore Rheumatoid Factor (RF) does not interfere with this test. Then, 119 renal allograft recipients were followed-up for the presence of seric IgM-CIC. Among them, 86 patients developed a recurrent Cytomegalovirus (CMV) infection and 33 did not. In the non-infected population, IgM-CIC were detected in only 15.2% of the patients. In contrast, patients with recurrent CMV infection showed a significantly higher frequency of detectable IgM-CIC (62.8%) (p less than 0.01). These IgM-CIC were detected: (a) during the first two or three weeks after graft; (b) in the course of the second month post graft. This second peak of IgM-CIC was never observed in subjects non-infected with CMV. IgM-CIC occurred before or at the same time as the detectable anti-CMV IgM and virus excretion in urines. Presence of IgM-CIC was not influenced by graft rejection episodes. Such a marker might help in discriminating immune response to viral infection from immune graft rejection.

Antibodies, Viral↗
PubMed1989

Pattern of anti-cytomegalovirus IgM antibodies determined by immunoblotting. A study of kidney graft recipients developing a primary or recurrent CMV infection.

In order to improve the knowledge of the humoral immune response to CMV infection, we developed an immunoblotting technique which allowed a better analysis of the changes in the pattern of anti CMV-polypeptides IgM. We examined 234 sera belonging to 27 renal allograft recipients developing a primary or recurrent CMV infection and 12 non infected recipients. Thus we found that 11 main anti CMV-polypeptides IgM antibodies were present in over 25% of the infected patients. They reacted with proteins whose molecular weights ranged from 32K to 205K. We showed that anti-p 45-47 IgM antibodies were present in 100% of CMV infected recipients and never in the non-infected population. They appeared very early in the course of the infection (5.43 weeks post-graft for primary infection and 5.00 weeks for recurrent ones) and, therefore, constitute a good marker of active infection. Two other CMV-specific IgM antibodies (anti-p 60-64 and anti-p 100) were found exclusively in the course of primary infections. Anti-p 60-64 IgM was observed at a high frequency (57.1%) and with a mean delay of 6.57 weeks post-graft. Therefore, the anti-p 60-64 IgM detection could be helpful for the diagnosis of primary infection. In almost 100% of both primary and recurrent infections, we observed anti-p 140 and anti-p 38 IgM antibodies. Only about 50% of non-infected patients had low levels of anti-p 140 and anti-p 38 IgM. The follow-up of recurrent infections showed that the anti CMV-polypeptides IgM antibodies appeared earlier than in primary infection. When we compared anti-p 45-47 IgM detection by immunoblotting and anti-CMV IgM detected by ELISA we observed that immunoblotting permitted the diagnosis 2.5 weeks earlier for primary infection, and 1 week earlier for recurrent infection, than ELISA. In addition, the detection of anti-p 45-47 IgM antibodies also occurred earlier than virus excretion.

Antibodies, Viral↗
PubMed1989

The use of a nitrocellulose-enzyme immunoassay for the rapid screening of monoclonal antibodies to human enteroviruses.

A simple, indirect enzyme immunoassay using purified enterovirus adsorbed on to nitrocellulose has been developed for screening monoclonal antibodies to enteroviruses. The sensitivity of the assay ranged from 10 ng to 1 microgram of viral protein and was 10- to 50-fold more sensitive than conventional EIA on microplates. This simple, sensitive and specific assay proved to be a useful and practical tool for detecting monoclonal antibodies which would not be found in a conventional EIA screening procedure.

Animals↗
PubMed1989

Rapid diagnosis of influenza infection of NP antigen using an immunocapture ELISA test.

An immunocapture ELISA test for the diagnosis of human and animal influenza A and/or B is described. A monoclonal anti-nucleoprotein (NP) antibody was used to capture the NP antigen and the captured antigen was detected by an anti-NP polyclonal rabbit antiserum. Compared with the usual diagnostic method by cultivation in embryonated eggs, this test had a high specificity (97%) and sensitivity when used for diagnosis using clinical nasopharyngeal samples obtained from patients and animals. Immunocapture ELISA permitted an easier reading than the indirect immunofluorescence technique. It also permitted diagnosis in frozen samples (-20 degrees C) or in infected LLCMK2 cells mixed with uninfected nasopharyngeal cells and kept at 20 degrees C for one week. This test can be carried out in 3 h.

Animals↗
PubMed1988

Use of cRNA probes for the detection of enteroviruses by molecular hybridization.

Subgenomic fragments of cDNA from poliovirus type 1 were inserted downstream from the SP6 or the T7 promoter in a Gemini riboprobe vector and their in vitro synthesized RNA transcripts were used as radiolabeled probes for the detection of enteroviral RNAs by molecular hybridization. The cRNA transcripts appeared to be more sensitive probes than the corresponding cDNAs. In vitro transcripts of the 5' noncoding region (5' nc riboprobe) were able to detect all of 14 reference enterovirus strains tested, as well as human rhinovirus 2, by dot blot hybridization with infected cell lysates. The same riboprobe also detected the enteroviral RNAs present in 16 of 18 samples of successive passages of stools in tissue culture and in some cases even in crude stool extracts. A riboprobe from the VP 1 region detected specifically poliovirus types 1, 2, and 3 in lysates of infected cells and in 50% of the infected stool specimens tested. These probes could be of particular interest for the epidemic survey of poliovirus infections.

Cell Line↗
PubMed1988

Prophylactic and therapeutic effects of murabutide in OF1 mice infected with influenza A/H3N2 (A/Texas/1/77) virus.

The antiviral activity of a novel biological response modifier (murabutide MDP derivative) has been investigated in 3-week-old OF1 mice infected with influenza (A/Texas/1/77) virus. In each experimental and control group, 10 mice were infected intranasally with a viral dose producing 50% mortality in 5 days and received murabutide via the subcutaneous or intranasal route at various doses either in a simple or in daily repeated administration. All experiments were done in triplicate. Significant prophylactic or therapeutic effects were observed when murabutide was administered the same day as virus, 4 days or 2 days before virus, and 2 days later. These effects varied with the route of administration and the doses of the compound.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Incidence and prognosis of cytomegalovirus infections following allogenic bone marrow transplantation.

The incidence and the outcome of cytomegalovirus (CMV) infections were evaluated in 83 adult recipients of allogenic bone marrow transplantation. Virological and serological surveillance was performed weekly for 3 months posttransplant, and then every other week or every month until 1 year. CMV infection occurred in 45 patients, with a cumulative risk of 62% at 1 year and 66% at 2 years. In multivariate analysis, two factors significantly influenced the incidence of CMV infection: patients with pretransplant positive anti-CMV titres had a risk of infection of 72% at 1 year versus 33% for patients with negative titres. Patients with acute myeloid leukemia were also infected more frequently (85% at 1 year) than patients with acute lymphoblastic leukemia (56%), chronic granulocytic leukemia (45%), or aplastic anemia (47%). In both univariate and multivariate analysis, CMV infection was not associated with a worse prognosis. However, 5 (out of 10) cases of lethal interstitial pneumonitis were associated with CMV, and two patients died of possible CMV encephalitis. All these patients had been suffering from severe acute or chronic graft versus host disease.

Adult↗
PubMed1987

HSV1 strain sensitivity in experimental rabbit keratitis: evolution under repeated topical IDU administrations.

The effects of repeated topical idoxuridine (IDU) administration of HSV1 strain sensitivity were investigated during 6 serial passages (P1 to P6) in the rabbit. By comparison to placebo treated rabbits, a delay in ulcer cicatrization appeared at P2 and clinical resistance was completed at P3. Clinical cross resistance to acyclovir (ACV) was also tested and demonstrated at P7. In vitro, a plaque reduction test on Vero cells using directly the tear film HSV populations allowed the prediction of the resistance by an early rise in the effective dose 90% (ED 90) value anticipating that in ED 50%. An ED 50 determination by dye-uptake assay on P6 HSV isolate demonstrated a cross resistance to viral thymidine kinase (TK) dependent drugs without any change in Ara-A and PFA sensitivity, according to a 23% TK activity at P6. At the last passage the HSV drug resistant population had an unrestricted corneal pathogenicity. A return to IDU and ACV in vitro sensitivity was demonstrated in group control animals at P2 but not at P4 or P6.

Acyclovir↗
PubMed1987

Prevalence of CMV ELISA antibody: titer and neutralizing activity in intramuscular immune globulin of placental origin.

The treatment of human CMV infection in transplant recipients by intravenous or intramuscular administration with high doses of hyperimmune or normal Ig showed inconsistent results. In fact, all hyperimmune Ig preparations were produced from high anti-CMV Ab titer plasma selected either by ELISA, complement fixation, or indirect hemagglutination test. These tests may not investigate the neutralizing activity of antibodies (Ab). We, therefore compared the ELISA titers with the neutralizing Ab titers in various normal Ig preparations from plasma or placenta and for intramuscular or intravenous use. Hyperimmune plasmatic Igs were also included. All the preparations were tested at a 5% dilution. We report the following data: (1) There is a poor correlation between ELISA and neutralization test. (2) The Igs of placental origin have significantly higher ELISA anti-CMV Ab titers than plasmatic normal Igs. They show the same neutralizing activity. (3) When compared with the normal intravenous Ig, normal intramuscular Igs show significantly higher titers with both techniques (P less than .0001). (4) Normal intramuscular Igs from placenta offer similar ELISA Ab titers and similar or higher neutralizing activity than hyperimmune Igs purified from plasma. It would be worth using Igs with high neutralizing activity in CMV prophylaxis in order to correlate in vitro tests and in vivo protection. In this respect, normal intramuscular Igs from placenta might be challenged in a clinical trial.

Antibodies, Viral↗
PubMed1987

[Risk of transmission of cytomegalovirus infection from mother to newborn infant].

A systematic prospective study of the incidence of cytomegalovirus (CMV) infection during pregnancy and contamination of the neonate was set up in a Maternity Hospital in Lyons. Over 7,000 pregnancies have been followed up since 1982 with serological and virological investigations. CMV infection was found in 5 p. 100 of patients. A urine collection was obtained at birth in 641 of the neonates. CMV was isolated in 16 cases and the transmission of the infection was studied with respect to the immune status of the mother. When CMV infection was demonstrated in the mother by serology and excretion of the virus, 45.5 p. 100 of babies were contaminated (10/22). In cases of reinfection, the incidence of neonatal contamination was 3.1 p. 100 (3/98). Ten of the 11 primary infections diagnosed were associated with viral excretion and the infection was transmitted to the child in 50 p. 100 of cases (5/10). The high incidence of transmission of CMV infection after a primary maternal infection supports data previously published by Stagno and Kumar in the U.S.A. and Ahlfors in Sweden.

Cytomegalovirus Infections↗
PubMed1987

Oral poliovirus vaccine in tropical Africa: greater impact on incidence of paralytic disease than expected from coverage surveys and seroconversion rates.

During the first 5 years of a poliomyelitis control programme in Yaounde, Cameroon, a maximum of 35% of children aged 12-23 months were estimated to have received three doses of trivalent oral vaccine. Despite this low immunization coverage and low seroconversion rates, which were determined concurrently, the estimated incidence of paralytic poliomyelitis decreased by 85%.A detailed study of immunized children and of children living in the same households suggests that community spread of the vaccine virus and cross-immunity may have partly been responsible for the dramatic decrease in the incidence of paralytic disease, and that competing non-polio enterovirus infection was not a cause for the low seroconversion rates. These results suggest that immunization coverage and seroconversion rates alone are not sufficient criteria for determining the effectiveness of control programmes that use oral poliovirus vaccine in tropical Africa; surveillance of the incidence of paralytic disease must also be carried out.

Antibody Formation↗
PubMed1986

A rapid and automated colorimetric assay for evaluating the sensitivity of herpes simplex strains to antiviral drugs.

A rapid and sensitive colorimetric assay has been developed to evaluate the sensitivity of herpes simplex viruses (HSV) to antiviral agents. The chessboard titration of viruses and antiviral drugs and the automatic reading and analysis of the data allows objective and accurate results to be rapidly obtained. Virus sensitivity was expressed as an ED50 value which was the concentration of drug (micrograms/ml) reducing viral cpe by 50%. The ED50 values of antiviral drugs [acetylguanosine (ACV), idoxuridine (IDU), deoxycytidine (IDC) and bromovinyl deoxyuridine] for several HSV reference strains were determined and the method was then applied to clinical specimens. The selection of ACV and IDU resistant mutants was performed on a cloned sensitive HSV 1 ocular strain. We observed cross-resistance between ACV and IDU for the mutants isolated. The resistance to thymidine-kinase-dependent antiviral agents varied in inverse ratio to the thymidine kinase activity induced by HSV strains.

Antiviral Agents↗
PubMed1986

Catalytic properties of the A/H3N2 influenza neuraminidases: influence of antigenic variations.

Antigenic variation of the neuraminidase of A/H3N2 influenza viruses may be associated with modifications of the catalytic activity of this enzyme. We observed this phenomenon when studying two prototype strains: A/Hong Kong/1/68 (X31K) and A/Bangkok/2/79. For the neuraminidases of these strains, we determined their substrate specificity, initial velocity, optimum pH, optimum temperature, heat inactivation and Michaelis constants and their inactivation by chemical group-specific reagents. In order to examine the relationship between antigenic variation and enzyme activity of the influenza neuraminidases, three X31K monoclonal variants were selected using anti-neuraminidase monoclonal antibodies. Two of these (X31/NC92 and X31/NC56) were modified at a single neuraminidase epitope, and the third one (X31/NC92/NC56) at two epitopes. The neuraminidase activity of the monoclonal variants was analysed and compared to that of the prototype strains. Compared to A/Hong Kong/1/68, the A/Bangkok/2/79 strain neuraminidase was more susceptible to inactivation by physical (pH, temperature) and chemical agents [urea, dithiothreitol, 1-ethyl-3-(3-dimethylaminopropyl carbodiimide), iodoacetamide, acetic anhydride, 2,3-butanedione] and showed a twofold lower substrate affinity for N-acetylneuraminlactose. The neuraminidase activity of the monoclonal variants of X31K became more susceptible to inactivation by both physical and chemical agents than the original strain and exhibited various substrate affinities. Therefore, we conclude that the enzymic properties of the structurally conserved active sites of the neuraminidase molecule may be influenced by antigenic modifications that affect the variable areas of the neuraminidase and that the degree of this enzymic variation is related to the nature and number of the modified epitope(s). A local conformational change in the neuraminidase molecule reflected as antigenic variation could be involved in modification of enzyme activity.

Antigens, Viral↗