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The understanding of the immunopathology of infections caused by microsporidia has pinpointed the importance of T cell-mediated immunity. The immunopathology caused by the interesting protozoan parasite Encephalitozoon intestinalis, a microsporidium pathogenic in man, is not clearly understood. In this study, we demonstrate that a specific cellular immune response is implicated in the control of microsporidiosis infection in mice. Interferon (IFN)-gamma receptor knockout mice (IFN-gamma R(o/o)) developed a chronic infection with E. intestinalis, whereas a transient infection developed in wild-type mice. Encephalitozoon intestinalis proteins induced proliferation of murine spleen and mesenteric lymph node cells collected from infected mice. The host response to microsporidia infection was regulated by a specific pattern of cytokine protection. Spleen cells derived from resistant 129 Sv/Ev mice inoculated with E. intestinalis secreted significant levels of gamma-interferon and interleukin-2 but cells from highly susceptible IFN-gamma R knockout mice secreted high levels of interleukin-4 (mostly between 2 and 4 weeks post infection). This is the first report in which a specific cellular immune response against E. intestinalis infection is presented.

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Parasitic protozoa have been entrapped within sol-gel silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silicon alkoxide solution. They remain trapped within the growing oxide network formed upon hydrolysis and condensation of the alkoxide. Electron microscopy shows the preservation of the cellular organization and the integrity of the plasma membrane of entrapped parasites. Specific antigen-antibody reactions have been performed within the sol-gel matrix via enzyme-linked immunosorbent assays (ELISA) currently used for the diagnostic of visceral leishmaniasis. A clear-cut difference in optical density was measured between positive and negative sera from dogs. Entrapped protozoa antigens are still able to react with specific antibodies through the open porosity of the silica network. These results suggest that sol-gel matrices could be used for the development of immunodiagnostic assays requiring whole cell parasites as antigens.

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HIV antigens were detected by immunoelectron microscopy at the surface of human and simian T4 lymphocytes that had been infected in vitro. HIV antigens were detected at the surface of cells exhibiting viral particles but also at the surface of cells before the release of virions. The latter cells may be considered immunogenic since they are capable of triggering specific immune responses without the cytopathic effects due to viral release.

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Six monkeys of three different species (mangabey, macaque and baboon) were infected with human immunodeficiency type 2 (HIV-2) NIH-DZ using intraperitoneal or intravenous injections of cell-free HIV-2 or autologous HIV-2-infected cells with no prior immunostimulation. Viral expression was demonstrated by reverse transcriptase activity in cells after coculture with human peripheral blood lymphocytes or by electron microscopy. Serum was analyzed by western blot, enzyme-linked immunosorbent assay (detection of antigen and antibody), and neutralization assay carried out using immunofluorescence techniques. The 6 inoculated animals seroconverted during the 1st month after inoculation and remained persistently infected after 6-11 months. We also observed proviral DNA by genomic analysis in the six tested samples. No sign of immunodeficiency disease has been observed so far. The data suggest that HIV-2 infection of nonhuman primates provides an acceptable animal model to investigate vaccination or specific immunotherapeutic procedures.

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Mangabeys, macaques, and baboons persistently infected with human immunodeficiency virus (HIV)-2 NIH-DZ demonstrated no signs of immunodeficiency disease after 6-11 months following seroconversion. Thus Old World monkeys provide an animal model to investigate the effects of passive immunization (anti-HIV-2 antibodies) on HIV infection in primates.

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A principal feature of acquired immunodeficiency syndrome is depletion of T4 lymphocytes, which is partly due to a direct cytopathic effect of the virus. Both syncytial formation (viral-induced cell fusion) and premature cell death have been cited as the major cause for this phenomenon. By kinetic analysis of cell proliferation and cell lysis we show that the cytopathic effect correlates chiefly with virus production from infected cells, including giant syncytial cells. Most T4 cells were, at least transiently, infected by human immunodeficiency virus (human T-lymphotropic virus type IIIB strain); however, after phytohemagglutinin activation, only 10-30% of infected cells express virus (and die) at any one time, indicating that virus production, followed by cell killing, is linked to immune activation and cell differentiation. We also show that an interval exists before viral release, in which expression of viral antigens occurs on the cell surface, suggesting that infected cells are immunogenic before viral production. If so, they may induce a cell-mediated immune response that could minimize dissemination of human immunodeficiency virus, a possibility that has influenced our approaches to the development of a vaccine for prevention of acquired immunodeficiency syndrome.

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The first experimental immunization of humans against the AIDS retrovirus, HIV-1, was started in a series of HIV seronegative, healthy volunteers in November 1986. For the primary vaccination recombinant vaccinia virus (V25) expressing the complete gp160 env protein of the HTLV-IIIB strain of HIV-1 was introduced by scarification. This elicited a weak primary response which we subsequently attempted to enhance by additional immunizations (boosting), using four different immunization protocols. We report here that intravenous injection of paraformaldehyde-fixed autologous cells infected in vitro with V25 (individual D.Z.) gave the best results. This individual received second and third boosts of intramuscular gp160 derived from an HTLV-IIIB clone using the hybrid vaccinia virus/bacteriophage T7 expression system. An anamnestic humoral and cellular immune reaction was achieved for over one year after the original vaccination, with high levels of antibodies to the viral envelope, and neutralizing antibodies against divergent HIV-1 strains such as HTLV-IIIB and HTLV-IIIRF (also called HTLV-III HAT) after the first boost. In addition, group-specific cell-mediated immunity and cell-mediated cytotoxicity against infected T4 cells were obtained after the primary vaccine and enhanced by the boosts. Finally, skin tests showed both immediate and delayed hypersensitivity to gp160 in vivo. Although this protocol is not practical for a large scale vaccine trial, our results show for the first time that an immune state against HIV can be obtained in man.

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A new microsporidium is reported infesting the enterocytes of a Haitian patients with AIDS. The stages observed were diplokaryotic cells, sporogonial plasmodia, unikaryotic sporoblasts, and spores. Neither a sporophorous vesicle (pansporoblastic membrane) nor parasitophorous vacuole were differentiated around the developmental stages, which were in direct contact with the host cell cytoplasm. The polar tube (5-6 coils) was differentiated before fission of the sporogonial plasmodium. The mature spores measured 1.5 micron X 0.5 micron. The spore wall was very thin as the endospore was absent or poorly differentiated. The organism is named Enterocytozoon bieneusi n. g., n. sp. and is assigned to the suborder Apansporoblastina.

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Chronic diarrhoea is frequent in acquired immune deficiency syndrome (AIDS) but has been poorly investigated so far. We report four patients with AIDS in whom diarrhoea and malabsorption were outstanding features, and who underwent extensive digestive investigations. Diarrhoea was a presenting symptom in all subjects and was of secretory type in three of them. D-xylose and vitamin B12 were malabsorbed in all cases; steatorrhea was found in the two patients who could ingest significant amounts of fat. Faecal alpha 1-antitrypsin clearance was increased in all subjects. Search for digestive pathogens showed unusual protozoans in all patients: in case 1, optical and electron microscopy revealed the presence in the cytoplasm of villous enterocytes of Microsporidia protozoans still unreported in AIDS. Stool and jejunal fluid examination showed Isospora belli in case 2 and Cryptosporidium in cases 3 and 4. On histological and ultrastructural study the former was localised in the cytoplasm of a few enterocytes and the latter was scattered throughout the villus and crypt brush border. Otherwise small intestinal histology only showed minor non-specific changes and the enterocytes were ultrastructurally normal. In patient 3 the slow marker intestinal perfusion technique showed a profuse fluid secretion in the duodenum and proximal jejunum. All patients needed prolonged total parenteral nutrition. Cryptosporidium and Microsporidia could not be eradicated despite multiple drug trials. Isospora belli was transiently cured by pyrimethamine-sulphadiazine. Only patient 2 is presently at home, and patients 1, 3, and 4 died after two, six, and nine months of total parenteral nutrition, respectively.

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We study in the present paper two collections of Gregarines (all parasite of terrestrial arthropods) from the Ivory Coast and the Gaboon. Among the 17 species studied, three are new for science: Gregarina darchenae, Gregarina pycnoceri and Gigaductus africanus. The other species have been already found in closely related hosts.

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Study of 14 species of Gregarines from terrestrial arthropods (Myriapoda and Insecta) of south Korea. Some of them (Ramicephalus ozakii, Gregarina monoducta, Hoplorhynchus ozakii, Stylocephalus bahli) are typically asiatic whereas the others were already described from identical or similar european hosts.

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The occurrence of micronemes and paraglycogen in the cytoplasm of Spiriopsis adipophila (Arvy and Delage 1966) Arvy and Peters 1972, incites us to consider this parasite of Ephemeroptera larvae as the infesting stage of a Sporozoon. It could be in fact a new member of the Barrouxiidae, a family of Coccidia parasitic in Insects and Centipedes which are characterized by the production of monozoic spores.

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