OBJECTIVETo observe the morphological characteristics of Plasmodium yoelii schizogony in their ghost erythrocytes.

METHODSSaponify, hypotonic shock, and electron microscopy were used to observe the different fashions of erythrocytic parasites and their characteristic organellae in ghost erythrocytes.

RESULTSThe malarial parasites and their fine structures were dramatically well preserved in the ghost erythrocytes, such as the ring-like early trophozoites, the brassiere-like early schizonts, the emerging buds on the surface of late schizonts, and the grape-cluster like late schizonts. The cytostome, food vacuole, and crystallized malarial pigments were found in the early trophozoites. The proliferations of nucleoplasma and nuclear membrane as well as and the clot-like nuclear division were followed by the budding during the schizogony.

CONCLUSIONThe saponify technique that makes the erythrocytic malaria parasites and their fine organellae to be dramatically revealed in their ghost erythrocytes, may be a useful method in the Plasmodium biological research and anti-malaria immunological researches.

Animals ; Erythrocyte Membrane ; parasitology ; ultrastructure ; Female ; Mice ; Mice, Inbred BALB C ; Microscopy, Electron ; Plasmodium yoelii ; ultrastructure

OBJECTIVETo test the immunity of peritoneal monocytes against Plasmodium yoelii infected red blood cells (target cells).

METHODSSaponinized Plasmodium yoelii infected red blood cells (SPRBC, Ghost erythrocyte) were used to immunize mice i.p twice. Three weeks later, the infected red blood cells were injected i.p.; 90 min later, the total peritoneal cells were isolated and washed for scanning electromicroscopy to observe the effects of the peritoneal monocyte to the target cell.

RESULTSThe peritoneal cells of the immunized mice were activated after 90 min of the challenge of target cells. The size of the cell was not even and the pili on the cell surface turned to be long and densed. Cell interconnections were found among the cells. In some peritoneal monocytes, their cell plasma were scattered (omlette-like) or with the shape as "cellular bomb". The scattered or the sheeted pili and spredding cell plasma could adhere to the target cells which were perforated densely and damaged.

CONCLUSIONThe protective adaptive immunity exists in the peritoneal monocytes of immunized mice.

Animals ; Antibodies, Protozoan ; immunology ; Erythrocyte Membrane ; parasitology ; Female ; Malaria Vaccines ; immunology ; Mice ; Mice, Inbred BALB C ; Monocytes ; immunology ; ultrastructure ; Peritoneum ; cytology ; Plasmodium yoelii ; immunology ; ultrastructure

Malaria is an infectious disease affecting humans, which is transmitted by the bite of Anopheles mosquitoes harboring sporozoites of parasitic protozoans belonging to the genus Plasmodium. Despite past achievements to control the protozoan disease, malaria still remains a significant health threat up to now. In this study, we cloned and characterized the full-unit Plasmodium yoelii genes encoding merozoite surface protein 1 (MSP1), circumsporozoite protein (CSP), and Duffy-binding protein (DBP), each of which can be applied for investigations to obtain potent protective vaccines in the rodent malaria model, due to their specific expression patterns during the parasite life cycle. Recombinant fragments corresponding to the middle and C-terminal regions of PyMSP1 and PyCSP, respectively, displayed strong reactivity against P. yoelii-infected mice sera. Specific native antigens invoking strong humoral immune response during the primary and secondary infections of P. yoelii were also abundantly detected in experimental ICR mice. The low or negligible parasitemia observed in the secondary infected mice was likely to result from the neutralizing action of the protective antibodies. Identification of these antigenic proteins might provide the necessary information and means to characterize additional vaccine candidate antigens, selected solely on their ability to produce the protective antibodies.
Animals ; Anopheles ; Antibodies ; Clone Cells ; Coinfection ; Communicable Diseases ; Culicidae ; Humans ; Immunity, Humoral ; Life Cycle Stages ; Malaria ; Merozoite Surface Protein 1* ; Mice ; Mice, Inbred ICR ; Parasitemia ; Parasites ; Plasmodium yoelii* ; Plasmodium* ; Rodentia ; Sporozoites ; Vaccines

OBJECTIVETo explore the characteristics of protective immunity against Plasmodium yoelii (P.y.) infection by asexual blood-stages cellular vaccine.

METHODSThe particulate vaccines were constructed by saponin or double-distilled-water lysed parasitic red blood cells and inoculated into BALB/c mice by intraperitoneal injection (i.p.). Each group was challenged by the lethal erythrocytic P.y. parasites, and then their parasitemia and survival rates were detected. Expressions of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were detected by RT-PCR. ELISA showed the serum antibodies against the malaria challenge and their-subclasses. Special membrane protein was recognized by immunofluorescence assay.

RESULTSThe vaccination with saponified erythrocytic parasites protected the immunized mice against P.y. challenge, while double-distilled-water lysed vaccine did not (P < 0.01). This protection was characterized by the increase of both IFN-gamma/IgG2a and IL-4/IgG1. Meanwhile, MHC class I alpha chain molecule was recognized on the membrane of infected-erthythrocyte.

CONCLUSIONSaponified P.y. asexual blood-stage cellular vaccine has a significantly high protective immunity against this lethal P.y. malaria, and the immunity may be associated with the expression levels of IgG2a and IFN-gamma. MHC class I alpha chain on infected erythrocytes may play an important role in the successful immunization.

Animals ; Antibodies, Protozoan ; blood ; Enzyme-Linked Immunosorbent Assay ; Female ; Histocompatibility Antigens Class I ; blood ; Immunoglobulin G ; blood ; Malaria ; prevention & control ; Malaria Vaccines ; immunology ; Mice ; Mice, Inbred BALB C ; Plasmodium yoelii ; immunology ; Random Allocation ; Vaccination

OBJECTIVETo identify and clone a new full ORF gene of PyDyn (Plasmodium yoelii dynamin-like protein), and examine the protection of their expression products.

METHODUsing the P. yoelii Genome technology and RT-PCR.

RESULTSThe full ORF gene of PyDyn was amplified from mRNA of the erythrocytic stage of P. yoelii., three domains of PyDyn were expressed in E. coli., and the fairly positive immunogenicity of them was showed by IFA. The full ORF gene of PyDyn was 2,433 bp and encode 811 amino acids. Its Gene Bank access number is AF458071. PyDyn belongs to the dynamin-like protein family according to its property.

CONCLUSIONThe new full ORF gene of PyDyn is obtained and identified; their expressed domains are probably new candidates for malaria vaccine.

Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; Dynamins ; genetics ; immunology ; Escherichia coli ; genetics ; Genes, Protozoan ; genetics ; immunology ; Malaria Vaccines ; immunology ; Molecular Sequence Data ; Plasmodium yoelii ; chemistry ; genetics ; Protozoan Proteins ; genetics ; immunology ; Vaccines, Synthetic ; immunology

Objective To investigate the effect of T cell immunoreceptor with Ig and ITIM domains (TIGIT) on the function of CD8⁺ T cells in the lungs of Plasmodium infected mice. Methods The lungs of the mice infected with Plasmodium yoelii were isolated, weighed and photographed after 12 days' infection. After dissolution, lung lymphocytes were isolated, counted and stained, and then the contents of CD8⁺ and TIGIT⁺CD8⁺ T cells were detected by flow cytometry. The expressions of L selectin (CD62L), CD69, programmed death 1 (PD-1), CD25, and C-X3-C motif chemokine receptor 1 (CX3CR1) on TIGIT⁺CD8⁺ T cells were detected by flow cytometry. After stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin, the ability of TIGIT⁺CD8⁺T cells to secrete interferon γ(IFN-γ), interleukin 21 (IL-21), IL-4, IL-17, and IL-10 was detected. Results The body mass of mice with Plasmodium infection was reduced. The lungs became darker, and the ratio of the lung mass to body mass was significantly increased. Compared with the normal mice, the percentages and absolute quantity of CD8⁺ and TIGIT⁺CD8⁺ T cells in the lungs of the infected mice were significantly increased. The percentage of TIGIT⁺CD8⁺ T cells expressing CD62L in the infected group was significantly lower, while the percentage of the CD69, PD-1, and CX3CR1 cells were significantly higher than that of TIGIT⁺CD8⁺ T cells from the normal mice. The percentages of TIGIT⁺CD8⁺ T cells secreting IL-21, IL-4, IL-17 and IL-10 cells in the infected group were significantly lower. Conclusion The lung lesions from mice with Plasmodium infection are obvious, the numbers of TIGIT⁺CD8⁺ T cells increase, and these cells express a variety of activation-related molecules, but the ability to secrete cytokines is reduced.
Animals ; Mice ; CD8-Positive T-Lymphocytes ; Cytokines/metabolism* ; Interferon-gamma/metabolism* ; Interleukin-10/metabolism* ; Interleukin-17/metabolism* ; Interleukin-4/metabolism* ; Lung/metabolism* ; Malaria/metabolism* ; Plasmodium yoelii/metabolism* ; Programmed Cell Death 1 Receptor/metabolism*