Jean-Paul Moreau

Mother‐to‐child transmission of human T‐cell‐leukemia/lymphoma virus type I: Implication of high antiviral antibody titer and high proviral load in carrier mothers

In order to gain new insights into the risk factors influencing human‐T‐cell‐leukemia/lymphoma‐virus‐type‐I (HTLV‐I) mother‐to‐child transmission, a retrospective study of HTLV‐I infection among children born to HTLV‐I‐seropositive women was carried out in a highly HTLV‐I‐endemic population of African origin living in French Guyana. The study covered 81 HTLV‐I‐seropositive mothers and their 216 children aged between 18 months old and 12 years old. All plasma samples were tested for the presence of HTLV‐I antibodies by ELISA, immunofluorescence assay and Western blot. HTLV‐I provirus was detected, in the DNA extracted from peripheral‐blood mononuclear cells, by polymerase chain reaction (PCR) using primers specific for 3 different HTLV‐I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. Out of the 216 children, 21 were found to be HTLV‐I‐seropositive, giving a crude HTLV‐I transmission rate of 9.7%, while among the 180 breast‐fed children 10.6% were HTLV‐I‐seropositive. Perfect concordance between serological and PCR results was observed, and none of the 195 HTLV‐I‐negative children was found HTLV‐I‐positive by PCR. In conditional (by family) logistic‐regression models, HTLV‐I seropositivity in children was associated with an elevated maternal anti‐HTLV‐I‐antibody titer (OR 2.2, p = 0.0013), a high maternal HTLV‐I proviral load (OR 2.6, p = 0.033) and childs gender, girls being more frequently HTLV‐I‐infected than boys: OR 3.6, p = 0.0077 in the model including maternal anti‐HTLV‐I‐antibody titer and OR 4.1, p = 0.002 in the model including the maternal HTLV‐I proviral load. Int. J. Cancer 82:832–836, 1999.

Demographic and familial characteristics of HTLV-I infection among an isolated, highly endemic population of African origin in French Guiana†

To determine the epidemiological characteristics of human T cell leukemia/lymphoma virus type I (HTLV‐I) infection in the endemic village of Maripasoula, French Guiana, 1,614 persons (83.2% of the population) aged 2 to 91 years (mean age 21) were studied from November 1994 through April 1995. Plasma samples were screened by an HTLV‐I ELISA and an IFA test (on MT2 cells), and positive samples were tested by an HTLV‐I and ‐II type‐specific Western blot. Overall seropositivity in the village was 6.7%, but HTLV‐I infection was restricted to 3 of 6 ethnic groups, including the Noir‐Marron (descendants of escaped African slaves, 8%), the Creoles (4.1%) and those of mixed Noir Marron/other ethnicity (3.6%). In the Noir‐Marron population of 1,222 persons, including 606 men and 616 women and representing 76% of those tested, HTLV‐I seroprevalence increased significantly with age in both sexes, reaching 40% in women older than 50 years. Univariate risk factors for HTLV‐I seropositivity in women included older age, more pregnancies, more live births and a history of hospitalization. A cross‐sectional analysis of sexual partners demonstrated an excess of discordant female HTLV‐I+/male HTLV‐I− couples, indicating preferential male‐to‐female sexual transmission. The demonstration of 11 HTLV‐I‐seropositive children aged less than 15 years, of whom 9 had a seropositive mother, suggested maternal–child HTLV‐I transmission. Our results demonstrate a very high seroprevalence of HTLV‐I in this South American population descended from African slaves, probably due to high rates of mother‐to‐child and sexual transmission within this rather isolated group. Int. J. Cancer 76:331–336, 1998.© 1998 Wiley‐Liss, Inc.

Hepatitis B Infection in Vanuatu: Age of Acquisition of Infection and Possible Routes of Transmission

Seroepidemiological studies of hepatitis B were carried out on diverse groups of children (477) and adults (629) from the Pacific Island country of Vanuatu. In children under 14 years, prevalences of HBsAg and of all markers were 6% and 53.3% respectively; in adults 20 years the prevalences were 15% and 70%. Age specific prevalence of hepatitis B infection (all markers) was low in infancy (< 1 year) but rose sharply afterwards, suggesting that the main mechanism of transmission was horizontal spread. This finding is consistent with other developing country studies from the Pacific Islands and elsewhere. In view of the main ages and mechanisms of transmission of hepatitis B in children in developing countries and the need for simple and inexpensive immunisation strategies in this context, it is recommended that mass vaccination of all infants with hepatitis B vaccine be undertaken in hyperendemic areas.

Stability-related studies on 17D yellow fever vaccine.

Yellow fever (YF) vaccine using the 17D strain of YF attenuated virus has been produced at the Institut Pasteur in Dakar since 1962. Until now, the stabilised YF had an expiry date of utilization of two years from the end of the lot control process under storage at +4 degrees C. We conducted a stability study to assess the three full year validity of this preparation, when correctly stored at +4 degrees C to optimise the conditions of production, storage and availability of such a vaccine. The activity of 19 consecutive batches of vaccines kept for three years at +4 degrees C was compared to that of the same batches that were kept three years at -20 degrees C. Using the in vitro microculture method, we found that three-year storage at +4 degrees C induced a higher loss of activity than storage at -20 degrees C or than the accelerated degradation test of vaccines kept for 14 days at 37 degrees C. Whatever the conditions of storage, in all cases decreases in activity were below the WHOs requirements, i.e., < 1 log PFU/dose, and residual activity of the selected batches was over 1000 mouse LD50 per dose. We demonstrated that the 17D YF vaccine produced in Dakar has a shelf-life of three years and that its required potency was maintained at +4 degrees C, after reconstitution with saline diluent, following three-year storage at +4 degrees C.

Antibody chimera technique applied to the detection of Escherichia coli heat-labile enterotoxin

Covalently prepared chimera antibodies were tested in a ganglioside GM1 erythro-immunoassay (CERIA) for E. coli heat-labile enterotoxin (LT) detection. The antibody specific for LT was conjugated with a polyclonal antibody specific for sheep erythrocytes. The assay is based on the specific binding of LT to polystyrene-adsorbed GM1 and subsequent erythro-adsorption via chimera antibody by which the bound toxin is visualized. Enterotoxin titers determined with this CERIA method were similar to those obtained with the Vero cell assay and with ELISA. 5 ng of cholera toxin/ml may be detected with the assay. The CERIA, as described, may be used either qualitatively or quantitatively and is well suited for routine laboratory diagnosis of LT in a culture supernatant of E. coli.

Détection spécifique de bentérotoxine thermolabile de Escherichia coli dans les selles humaines par épreuves immunoenzymatiques compétitves en présence d'inhibiteur des protéases

Abstract Two simple two-step competitive enzyme-linked immunoassays for human E. coli heat-labile enterotoxin (LTh) employing microtitration plates coated with rabbit anti-LTh antibody (ELISA) or GM1 ganglioside (GM1-ELISA) are described. LTh of the test sample competed with the same toxin coupled with horse-radish peroxidase. ELISA and GM1-ELISA were able to detect, respectively, as low as 5 ng and 6.5 ng TLh/ml and up to 9 and 11 μg TLh/ml. Both techniques were applied to the study of 167 infant diarrhoeas; ETEC producing LTh were identified in 17 diarrhoeal stools When the faeces were diluted in phosphate buffer, only 17.6 % (3 stools) and 29 % (5 stools) of LTh-positive faeces were identified in ELISA and GM1-ELISA. When the stools were diluted with phenylmethylsulphonyl fluoride (PMSF), a synthetic protcase inhibitor, 32 % (14 stools) and 88 % (15 stools) of LTh-positive stool supernatants were detected. Aprotinin, another protease inhibitor, was without effect and foetal calf serum, horse serum and bovine serum albumin enabled detection of only a low percentage of LTh-positive stools.

Étude comparativeentre l'adhérence aux entérocytes de lapins, la présence des facteurs de colonisation CFA/I et CFA/II et la toxinogénie de 55 souches de Escherichia coli

Summary Fifty-five strains of Escherichia coli isolated from 51 faeces of Melanesian children with acute diarrhoea in New Caledonia were studied; three diarrhoeas were bloody. For each strain, haemagglutination type, adhesion to rabbit enterocytes, serotype, production of heat-labile (LT) or heat-stable (ST) toxins and identification of colonization factor antigens CFA/I or CFA/II were determined. We identified 48 strains able to attach to rabbit enterocytes; 27 produced enterotoxins (21 strains LT+ and 6 ST+) and 19 had CFA (13 CFA/I and 6 CFA/II). Five serotypes were identified: O6, O78, O80, O114 and O127:B8. One strain, O127:B8, which was able to attach to enterocytes, had CFA/I and produced LT toxin.

Dosage de l'entérotoxine thermolabile de Escherichia coli et de Vibrio cholerae par inhibition de l'érythro-adsorption sur le ganglioside GM1

Abstract A GM1 erythroassay (GERYDO) for heat-labile Escherichia coli enterotoxin (LT) and cholera toxin (CT) is described. This assay was developed for use in poorly equipped laboratories in developing countries. It uses GM1-coated polystyrene plates and is based on the competition between the toxin to be assayed and CT covalently bound to sheep red blood cells. GERYDO can detect 0.9 or 0.5 ng of CT per ml depending on the method of sensitization of erythrocytes. Good quantitative and quaitative correlation with the enzyme-linked immunosorbent assay and the Vero cell test was observed.