New monoclonal antibody specific for Candida albicans germ tube.

Hydrophobic components of the germ tube of the dimorphic pathogenic fungus Candida albicans were used as immunogens to prepare monoclonal antibodies (MAbs). Among the resulting MAbs, one (MAb 16B1-F10) was shown by indirect immunofluorescence to be specific to the surface of the mycelium phase of the C. albicans and C. stellatoidea species. No labeling of any other genera and Candida species tested was observed, including C. dubliniensis, a newly described species which has many phenotypic similarities to C. albicans. This phase-specific epitope resides on a protein moiety. The molecular mass of the antigen released by Zymolyase digestion was determined by gel filtration and ranges from 25 to 166 kDa. The antigen was also shown to be highly hydrophobic. This anti-C. albicans cell wall surface-specific MAb may be a good candidate for use in tests for the rapid differentiation of the two closely related species C. albicans and C. dubliniensis.

Natural Haemophilus influenzae type b capsular polysaccharide antibodies in 412 infants and children from West Africa (Burkina-Faso) and France: a cross-sectional serosurvey.

Prior to possible introduction of large-scale vaccination programmes, an estimation and comparison of naturally acquired immunity against Haemophilus influenzae type b (Hib) was carried out in two populations of age-stratified infants and children (from birth to 14 years old) in Burkina-Faso (West Africa) (n = 206) and France (n = 206). Hib capsular polysaccharide antibodies were detected by an ELISA method. The difference in the percentages of minimum protective levels for the two populations were not significant (0.15 microg/ml) for newborns (0-1 month) but became significant as early as 2 to 3 months of age (p < 0.01) when lower levels were found among infants from Burkina-Faso. Subsequently, the percentages in both countries remained low until 11 months of age and showed no significant differences. For children between 12 and 35 months, the results > or = 0.15 microg/ml were significantly higher in France (p < or = 0.05). From 36 months, the percentage of minimum seropositivity increased in Burkina-Faso, so that the difference was no longer significant. In each country, the percentage of children with the minimum protective level varied significantly (p < or = 0.05) according to age (0-47 months). None of the children from Burkina-Faso or France had antibody levels > 1.0 microg/ml before one year of age. Thereafter, only 9.51% of French children in the 12- to 17-month age stratum and 19.2% over 4 years of age had antibody levels > 1.0 microg/ml. There were no non-detectable results for children over 4 years of age, and the means for natural detectable Hib CP antibodies were > 0.15 microg/ml for both populations. Hib invasive infections depend on climate, socioeconomic status and ethnic and genetic factors. In Burkina-Faso, the large number of infants and children under 4 years of age susceptible to Hib infections suggests that large scale vaccination programmes are needed soon after birth. However, it would first be necessary to evaluate such factors as the frequency of Hib diseases in this population.

Direct sequencing of hepatitis A virus strains isolated during an epidemic in France.

Direct sequencing of PCR products was used to study the VP1 region of the hepatitis A virus (HAV) genome (position 2199 to 2356) of nine strains isolated from human stools collected during a hepatitis A epidemic (western France, 1992), three strains from environmental samples (1990, 1991, and 1992), and two HAV cell culture isolates (the French strain CF53/Lyon and strain CLF). These viruses differed from CF53/Lyon (genotype I) by between 1 and 10.3%, and results indicated the existence of two groups of strains belonging to two different subgenotypes (IA and IB). With this sequencing technique it was possible to monitor the epidemiology of HAV and study its relations.

Development of RT-semi-nested PCR for detection of hepatitis A virus in stool in epidemic conditions.

The purpose of this study was to determine the efficiency of semi-nested PCR in detecting hepatitis A virus (HAV) RNA. During a 2-year period (1990-1991), HAV RNA was searched for in shellfish from the French Brittany coasts using cRNA and vRNA probes. In January 1992, at the time of a hepatitis A outbreak, 28 stool samples were collected from infected patients (18 adults, 10 children) with anti-HAV IgM. Four samples from subjects with negative HAV serology were used as negative controls. Nucleic acid amplification (reverse-transcription-semi-nested PCR) was performed to detect HAV in stool. HAV RNA was purified by phenol-chloroform extraction and converted to cDNA using reverse transcriptase (Mu-MLV). After amplification, PCR products were visualized on an ethidium-bromide-stained gel and confirmed by hybridization with a specific digoxigenin-labelled oligoprobe. Samples were also studied by molecular hybridization with cRNA and vRNA probes. After onset of the illness, HAV RNA was detected over a longer time period by semi-nested PCR (16/28) than by hybridization (0/28). Even though biological diagnosis of hepatitis A will continue to rely on the detection of anti-HAV IgM, PCR should be useful in certain clinical cases (diagnosis of relapse) and for epidemiological and environmental monitoring of viruses.

Use of genomic probes to detect hepatitis A virus and enterovirus RNAs in wild shellfish and relationship of viral contamination to bacterial contamination.

Genomic probes were used to investigate hepatitis A virus (HAV) and enterovirus RNAs in two types of shellfish from natural beds (Atlantic coast, France). After elution concentration, nucleic acid extracted by proteinase K and purified by phenol-chloroform and ethanol precipitation was assayed by dot blot hybridization. The probes used were a specific HAV probe corresponding to the 3' end (3D polymerase coding region) and an enterovirus probe corresponding to the 5' noncoding region. The method was first tested under experimental conditions by using virus-spiked shellfish before being applied under field conditions. Our results show that shellfish were highly contaminated: enterovirus and HAV RNAs were found in 63 and 67%, respectively, of samples examined with the riboprobes. On the same site, viral (HAV and enterovirus) RNAs were found in a larger fraction of cockles than mussels. Statistical tests of dependence showed no relationship between viral contamination and bacterial contamination (evaluated by fecal coliform counts).

HIV infection and severe malnutrition: a clinical and epidemiological study in Burkina Faso.

OBJECTIVE: To define a clinical profile indicative of HIV infection in a population of severely malnourished children in Burkina Faso. A total of 433 children (average age, 19 months) were recruited at the Sanou Souro National Hospital, Bobo Dioulasso, Burkina Faso. RESULTS: Sixty-three per cent presented with marasmus, 13% with kwashiorkor and 24% with both forms of malnutrition. The prevalence of HIV infection in children aged over 12 months was 13.8%, with a marked predominance of HIV-1 (95.8%). Mother-to-child transmission was proven in 77% of the cases; in 10% of the observed paediatric AIDS cases, transmission may have occurred through multi-injections with contaminated equipment. Marasmus was the form of malnutrition most frequently associated with HIV (P < 0.001); its severity was exacerbated by HIV infection. Adenopathy (P < 0.0001), oral candidiasis (P < 0.0006), skin disorders (P < 0.01) and hepatomegaly (P = 0.01) appeared to be significantly related to HIV infection. Discriminant analysis revealed that the presence of adenopathies was the strongest indicator symptom of HIV infection. Multivariate analysis revealed that a clinical profile of marasmus, adenopathies and oral candidiasis (specificity, 82%) was indicative of HIV infection in this population. The short-term clinical prognosis was poor and usually led to the death of the child when seropositive (P < 0.001). CONCLUSIONS: Among children exhibiting severe malnutrition, HIV-positive children are distinguished by a high horizontal transmission rate, a high specific clinical profile and a very poor prognosis.

PIP: Clinically, malnutrition appears as the last stage in pediatric AIDS. It is, however, difficult to determine the causes of malnutrition without diagnostic facilities and in the absence of differentiating clinical criteria. The authors therefore set out to determine the prevalence of HIV in children, to assess the various modes of infection in children, and to define a clinical profile indicative of HIV infection in malnourished children. They found that among children exhibiting severe malnutrition, HIV-seropositive children are distinguished by a high horizontal transmission rate, a high specific clinical profile, and a very poor prognosis. The study population consisted of 433 severely malnourished children of average age 19 months, in the range 4-48 months, admitted to the Sanou Souro National Hospital in Burkina Faso. 63% presented with marasmus, 13%% with kwashiorkor, and 24% with both forms of malnutrition. 13.8% of children older than 12 months were infected with HIV; HIV-1 in 95.8% of these cases. Mother-to-child transmission was proved in 77% of cases; in 10% of the observed pediatric AIDS cases, transmission may have occurred through multi-injections with contaminated equipment. Marasmus was the form of malnutrition most frequently associated with HIV, with its severity exacerbated by HIV infection. Adenopathy, oral candidiasis, skin disorders, and hepatomegaly appeared to be significantly related to HIV infection. Discriminant analysis, however, revealed that the presence of adenopathies was the strongest indicator symptom of HIV infection. Multivariate analysis defined a clinical profile of marasmus, adenopathies, and oral candidiasis as indicative of HIV infection in the population. The short-term clinical prognosis for the infants was poor and usually led to the death of the child when seropositive.