Molecular detection and characterization of yellow fever virus in blood and liver specimens of a non-vaccinated fatal human case.

A yellow fever virus of a South American genotype was identified in the liver and blood samples of a non-vaccinated European patient after his return from Brazil. ELISA tests were negative for IgG and positive for IgM against yellow fever. Yellow fever proteins in the formalin-fixed and paraffin-embedded liver biopsy were detected by immunohistochemical procedures. Viral RNA extracted from the liver tissue was also detected using an RT-semi-nested PCR procedure and molecular hybridization. Alignment of the sequence obtained from a gene fragment amplified by RT-semi-nested PCR directly from a blood sample with those of African and South American yellow fever virus strains identified a Brazilian topotype as being responsible for the disease. RT-semi-nested PCR may be used advantageously for clinical specimens for rapid and specific diagnosis, and with archival biopsy material for retrospective studies.

Attenuated virulence of uridine-uracil auxotrophs of Aspergillus fumigatus.

Aspergillus fumigatus mutants that are deficient in the de novo UMP biosynthesis pathway because of a mutation in the pyrG gene encoding orotidine-5'-phosphate decarboxylase (and therefore auxotrophic for uridine or uracil) were evaluated in a murine model of invasive aspergillosis. These mutants were entirely nonpathogenic, and mutant conidia remained ungerminated in alveolar macrophages. Both the germination and virulence defects could be restored by supplementing the drinking water of the animals with uridine. DNA-mediated transformation of one of the pyrG mutants with the Aspergillus niger pyrG gene also restored virulence. These results suggest that uridine and uracil are limiting in the lung environment, thus preventing conidium germination and hence virulence of the pyrG mutants.

The GroES homolog of Helicobacter pylori confers protective immunity against mucosal infection in mice.

Helicobacter pylori is an important etiologic agent of gastroduodenal disease. In common with other organisms, H. pylori bacteria express heat shock proteins that share homologies with the GroES-GroEL class of proteins from Escherichia coli. We have assessed the heat shock proteins of H. pylori as potential protective antigens in a murine model of gastric Helicobacter infection. Orogastric immunization of mice with recombinant H. pylori GroES- and GroEL-like proteins protected 80% (n = 20) and 70% (n = 10) of animals, respectively, from a challenge dose of 10(4) Helicobacter felis bacteria (compared to control mice, P = 0.0042 and P = 0.0904, respectively). All mice (n = 19) that were immunized with a dual antigen preparation, consisting of H. pylori GroES-like protein and the B subunit of H. pylori urease, were protected against infection. This represented a level of protection equivalent to that provided by a sonicated Helicobacter extract (P = 0.955). Antibodies directed against the recombinant H. pylori antigens were predominantly of the IgG1 class, suggesting that a type 2 T-helper cell response was involved in protection. This work reports a protein belonging to the GroES class of heat shock proteins that was shown to induce protective immunity. In conclusion, GroES-like and urease B-subunit proteins have been identified as potential components of a future H. pylori subunit vaccine.

[Human protothecosis and environment]. / Protothécoses humaines et environnement.

Protothecosis are uncommon infections caused by Prototheca, considered to be achlorophylous algae. Nearly 80 human cases are reported in the literature since the first case described by Davies and Wakelin in 1964 in Sierra Leone (11). The disease have been identified in Europe, Asia (Japan, Thailand, China), Oceania and in the United States with 40 cases, particularly in the Southeast. Clinically, three clinical manifestations can be observed: 1) cutaneous lesions: papules, plaques or eczematoid, papulo-nodular areas of the extremities, 2) olecranon bursitis which occurred in 25% of cases, 3) systemic protothecosis. An immunosuppressive factor local or general can be found in half of the cases and the first description of algal meningitis was reported in a patient with AIDS in association with Cryptococcus neoformans. Because the disease is clinically not suspected, the diagnosis is often provided by histology showing a dermic granuloma with endospores. The characteristic feature of protothecosis in tissues is the presence of specific mature sporangia of Prototheca wickerhamii with the pattern of morula. The organism was PAS, Grocott and mucicarmin positive. The ecology was studied by Clark (7), Pidoux (23), Pore (25) and Sudman (27). Prototheca are ubiquitous inhabitants of sewages and are found in slime flux and animal wastes contaminating different aquatic systems. The transmission generally occurred by traumatic inoculation. Prototheca are also found in the digestive system of man and animals without never invasion of the epithelium and mucosae in experimental models. The pathogenicity and virulence are moderate and they are considered as rare opportunistic agents.

Immunohistochemical identification of ferritin, lactoferrin and transferrin in leprosy lesions of human skin biopsies.

Granulomatous lesions of human leprosy contained ferritin and lactoferrin but little or no transferrin, as demonstrated by the avidin-biotin complex immunoperoxidase method. Lactoferrin was found in the neutrophils. These results suggested that the cells of the host mononuclear phagocyte system in leprosy granulomas provide an adequate nutritional environment for iron acquisition by M. leprae. A possible role of iron binding proteins in the granulomas is discussed in relation to previous data on bovine paratuberculous granulomas.