| laminin on toxoplasma gondii mediates parasite binding to the beta 1 integrin receptor alpha 6 beta 1 on human foreskin fibroblasts and chinese hamster ovary cells. | we investigated the role of parasite-bound laminin and the host cell beta 1 integrin receptors for this extracellular matrix protein in toxoplasma gondii binding to fibroblasts. laminin but not fibronectin was detected on extracellular tachyzoites by immunofluorescence and immunoblotting. binding of parasites to cho cells was inhibited by polyclonal antibodies to laminin and by a monoclonal antibody directed against the globular carboxyl-terminal portion of the long arm of laminin (at or near th ... | 1992 | 1399003 |
| attachment of toxoplasma gondii to host cells is host cell cycle dependent. | the initial attachment of toxoplasma tachyzoites to target host cells is an important event in the life cycle of the parasite and hence critical in the pathogenesis of this infection. the efficiency of toxoplasma attachment to synchronized populations of chinese hamster ovary cells and bovine kidney cells was investigated by using a glutaraldehyde-fixed host cell assay system. for both cell lines, parasite attachment increased as the synchronized host cells proceeded from the g1 phase to the mid ... | 1996 | 8926075 |
| evaluation of the protective effect of deoxyribonucleic acid vaccines encoding granule antigen 2 and 5 against acute toxoplasmosis in balb/c mice. | abstracttoxoplasma gondii infects a broad range of warm-blooded hosts, including humans. important clinical manifestations include encephalitis in immunocompromised patients as well as miscarriage and fetal damage during early pregnancy. toxoplasma gondii dense granule antigen 2 and 5 (gra2 and gra5) are essential for parasitophorous vacuole development of the parasite. to evaluate the potential of gra2 and gra5 as recombinant dna vaccine candidates, these antigens were cloned into eukaryotic ex ... | 2017 | 28719288 |
| starvation of low-density lipoprotein-derived cholesterol induces bradyzoite conversion in toxoplasma gondii. | lacking enzymes for sterol synthesis, the intracellular protozoan toxoplasma gondii scavenges cholesterol from host cells to multiply. t. gondii has a complex life cycle consisting of two asexual stages; the proliferative stage (tachyzoite), and the latent stage characterized by tissue cysts (bradyzoite). in vitro, bradyzoite development can be induced by mimicking host immune response stressors through treatment with ifn-γ, heat shock, nitric oxide, and high ph. however, the extent to which hos ... | 2014 | 24885547 |
| cloning and expression of major surface antigen 1 gene of toxoplasma gondii rh strain using the expression vector pvax1 in chinese hamster ovary cells. | toxoplasmosis is an opportunistic protozoan infection with a high prevalence in a broad range of hosts infecting up to one-third of the world human population. toxoplasmosis leads to serious medical problems in immunocompromised individuals and fetuses and also induces abortion and mortality in domestic animals. therefore, there is a huge demand for the development of an effective vaccine. surface antigen 1 (sag1) is one of the important immunodominant surface antigens of toxoplasma gondii, whic ... | 2015 | 25861441 |
| the distribution pattern of α2,3- and α2,6-linked sialic acids affects host cell preference in toxoplasma gondii. | tachyzoites of toxoplasma gondii, an obligate intracellular parasite, actively invade almost all types of nucleated cells. however, t. gondii tachyzoites preferentially infect particular types of animal tissue cells. the mechanism underlying the host cell preference of t. gondii is not yet known. in this study, we found that enzymatic removal of α2,3- but not α2,6-linked sialic acids on the surface of vero cells decreased t. gondii tachyzoite adhesion or invasion to the treated cells. although c ... | 2015 | 26003519 |
| activation of tlr2 and tlr4 by glycosylphosphatidylinositols derived from toxoplasma gondii. | gpis isolated from toxoplasma gondii, as well as a chemically synthesized gpi lacking the lipid moiety, activated a reporter gene in chinese hamster ovary cells expressing tlr4, while the core glycan and lipid moieties cleaved from the gpis activated both tlr4- and tlr2-expressing cells. myd88, but not tlr2, tlr4, or cd14, is absolutely needed to trigger tnf-alpha production by macrophages exposed to t. gondii gpis. importantly, tnf-alpha response to gpis was completely abrogated in macrophages ... | 2007 | 17617606 |
| cell surface heparan sulfate promotes replication of toxoplasma gondii. | previous work suggests that cell surface heparan sulfate acts as a receptor for the apicomplexan parasite toxoplasma gondii. using chinese hamster ovary cell mutants defective in heparan sulfate biosynthesis, we show that heparan sulfate is necessary and sufficient for infectivity. further, we demonstrate that the parasite requires n sulfation of heparan sulfate initiated by n-deacetylase/n-sulfotransferase-1, but 2-o sulfation and 6-o sulfation appear to be dispensable. in order to study the ro ... | 2005 | 16113255 |
| host cell surface sialic acid residues are involved on the process of penetration of toxoplasma gondii into mammalian cells. | tachyzoites of toxoplasma gondii are able to infect several cell types tested (wild-type chinese hamster ovary (cho) cells and glycosylation mutants, vero and llcmk2 cells). however, the extent of infection varied. mutant cells which present few or no surface-exposed sialic acid residues were infected to a lower extent. similar results were obtained if sialic acid residues were removed by previous neuraminidase treatment. addition of sialic acid residues to surface-exposed glycoconjugates using ... | 1998 | 9682481 |
| identification of highly potent and selective inhibitors of toxoplasma gondii dihydrofolate reductase. | toxoplasma gondii rh was obtained in high yield from culture in rpmi medium on a line of chinese hamster ovary cells lacking dihydrofolate reductase activity (atcc 3952 dhfr-; american type culture collection). dihydrofolate reductase preparations from harvested organisms had specific activities of 22.9 +/- 2.1 nmol/min/mg. the 50% inhibitory concentrations against reference compounds were 0.014 microm for methotrexate, 0.24 microm for pyrimethamine, 2.7 microm for trimethoprim, and 0.010 microm ... | 1993 | 8239605 |
| localization of azithromycin in toxoplasma gondii-infected cells. | agents effective against intracellular pathogens must enter infected cells, crossing vacuolar membranes surrounding the organisms and then penetrating into the microbe and localizing to the microbial target site. we have characterized these parameters for azithromycin entry into toxoplasma gondii-infected chinese hamster ovary cells and murine macrophage-like j774 cells. azithromycin uptake into infected host cells was concentrative and was dependent upon proton gradients. subcellular fractionat ... | 1994 | 7979295 |
| [antigen analysis of toxoplasma gondii lysate and excretory-secretory materials by enzyme-linked immunoelectrotransfer blot (eitb)]. | recently, the importance of toxoplasmosis is raised as a complication in immunosuppressed or aids patients. our study focused on the identification of a variety of toxoplasma antigens by immunoblotting. rabbits and balb/c mice were immunized with toxoplasma lysate (rh strain), frozen tachyzoites (rh strain) or cysts (beverly and fukaya strain). blood were collected from ear vein, heart or orbital plexus for detecting the serum antibody levels. for excretory-secretory (e.s) antigens, t. gondii (r ... | 1994 | 7834242 |
| pyrimidine synthesis by intracellular toxoplasma gondii. | pyrimidine biosynthesis was studied in actively dividing, intracellular toxoplasma gondii, in mutant chinese hamster ovary cells blocked in pyrimidine biosynthesis to eliminate any contribution by the host cell. the parasite grew normally in these cells even though pyrimidines were not supplied in the medium. uninfected, mutant cultures showed negligible pyrimidine synthesis. however, mutant cultures infected wit t. gondii efficiently incorporated 14c from glucose or aspartic acid into the pyrim ... | 1981 | 7241272 |
| toxoplasma gondii: fusion competence of parasitophorous vacuoles in fc receptor-transfected fibroblasts. | after actively entering its host cells, the protozoan parasite toxoplasma gondii resides in an intracellular vacuole that is completely unable to fuse with other endocytic or biosynthetic organelles. the fusion blocking requires entry of viable organisms but is irreversible: fusion competence of the vacuole is not restored if the parasite is killed after entry. the fusion block can be overcome, however, by altering the parasite's route of entry. thus, phagocytosis of viable antibody-coated t. go ... | 1990 | 2200126 |