Biomedical subjects
Publications and source records attributed to R Teyssou.
We report a case of shigellosis observed in a young French sanitary assistant, returning from a refugees camp in Goma after a 5-week stay. Three different species were isolated from stool samples: Shigella flexneri, S. boydii and S. sonnei. This observation raises the matter of a chemical prophylaxis during a short stay in developing countries where sanitary conditions are poor.
In vitro production of specific antibodies or IVPA is a technique that involves isolating mononuclear cells from blood, placing them in culture, and detecting antibodies in the culture supernatant. The presence of antibodies confirms active production by B lymphocytes and is proof of ongoing infection. To validate this technique for routine laboratory use, we tested 16 subjects: 11 for toxoplasmosis and cytomegalovirus and 5 for viral hepatitis type A or B. The results obtained using IVPA were compared with those obtained using conventional serologic methods. IVPA documented IgM for cytomegalovirus in the only subject in whom serology showed IgM for that virus. The test was also positive in 2 subjects undergoing vaccination for viral hepatitis type B and suffering from acute viral hepatitis type A. These concordant results demonstrate that IVPA is a valuable adjuvant technique for diagnosis of ongoing infection especially insofar as it avoids the need for antibody kinetic studies or isolation of the virus. It also provides a simpler and less expensive alternative to gene amplification and cell culture.
A polymerase chain reaction (PCR) system was developed for the detection of mollicutes as contaminants of cell cultures. By using three oligonucleotides chosen in the 16S rDNA sequences, two sets of primers able to promote amplification of all Mycoplasma and Ureaplasma (molli1-molli2a) or all Acholeplasma (molli1-molli2b) species examined were determined. This PCR system, first applied to experimentally infected Vero cell lines, was then evaluated for the detection of mollicutes in 86 cell culture samples, comparatively to DNA staining, culture and ELISA. The results obtained by the four techniques were in agreement in 82 cases (36 positive, 46 negative). PCR allowed detection of contamination in one and two cases negative by ELISA and culture, respectively, and confirmed questionable results obtained by DNA staining. As described, PCR seems to be a very convenient tool for routine detection of cell culture contaminants.
A retrospective investigation permitted us to show presence of HIV infection in Burundi between 1980 and 1981. 658 sera collected in healthy population of Burundi during this period have been tested for HIV1 and HIV2 with ELISA screening and western-blot analysis. Results completed with HIV1 antigen research show 29 patients infected with HIV1 (27 antibodies to HIV1 carriers, and 2 with HIV1 antigen). The epidemiological situation before finding HIV show high prevalence (4.4%) of HIV1 infection. No HIV2 was found. The epidemiology of HIV infection was dominated by high prevalence in urban areas (8.08%) but 2.82% of country people were infected, by frequence in man (5.94%) but 3.08% of women were carriers, and by heterosexual transmission. After this study HIV infection was more frequent and we have observed epidemiological modification (importance of vertical transmission). Frequent antigenic cross-reaction between HIV1 and HIV2 core proteins has been observed. Cross-reaction with other retrovirus is possible.
The authors have carried out, on 150 sera of patients seropositive for the human immunodeficiency virus type I (HIV I) and 11 cerebrospinal fluid of which 5 were patient infected by the HIV I, a comparative study of two commercial tests for the detection of HIV I antigen (Diagnostic Pasteur and Abbott laboratories). A much greater sensitivity was obtained with the specificity being practically identical for the sera with the two tests (100% with Abbott laboratories test, 96.11% with the diagnostic Pasteur test). 4 sera appeared "false negatives" with the Abbott Laboratories test; their optical density was situated between 80 and 100 p. cent of the cut-off level value, whereas that of the "real" negatives was situated between 30 and 60 p. cent of the cut-off level value. 10 of the 11 cerebrospinal fluids appeared false positive with the Diagnostic Pasteur. This seems to be connected with an insufficiency of saturation of protein receptors in the wells. The Diagnostic Pasteur test is not adapted for the detection of HIV I antigen in the body fluids with a weak protein concentration. Contrary to the results obtained with the Encavor test (Abbott laboratories) the analysis in western-blot does not show an inverse prevalence of anti p24 GAG antibodies with regard to antigen HIV I in seropositive patients. On the other hand, the statistical analysis of the positive HIV I sera which are at the same time antigen HIV I positive and antibodies HIV I positive suggests an earlier disappearance of anti p17 GAG antibodies than of anti p24 GAG antibodies.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Biological diagnosis of HCV infections consists of a two steps process. The first one is the detection, rarely induced by evocative symptoms, more often subsequent to systematic screenings. Third generation ELISA tests are used for this purpose on account of their high sensitivity. Their enhanced specificity, reaching 99.5%, still has to be checked using complementary tests, especially immunoblots assays. However, these methods may fail to detect specific antibodies during the acute phase of HCV infections or among immunodeficient patients, resulting in discrepancies or indeterminate conclusions. Then, the detection of HCV viremia by PCR is of great value to assert the diagnosis. The second step, before treatment, consists to identify the genotype and to determine the viral load by quantitation of the HCV RNA. Because the endemicity of HCV infections in France, these methods, although difficult an expansive, should be transferred to the medical laboratories, provided their quality and their accessibility will be preserved.