Immune responses against excreted/secreted antigens of Toxoplasma gondii tachyzoites in the murine model.
In the present study, excretory secretory antigens (ESA) of Toxoplasma gondii were evaluated in immunization of 8-10 week inbred female Balb/c mice. Tachyzoites of the parasite were cultured in cell-free incubation medium (RPMI-1640), and then supernatant of the medium was loaded on an ion-exchange chromatography column. Two fractions (ESA-F(1) and ESA-F(2)) were collected from the column. For immunization of the mice, 50 were allocated into 5 groups of 10. The first, second, third, and fourth groups were immunized, twice with total-ESA, ESA-F(1), ESA-F(2) or toxoplasma lysate antigen (TLA), respectively. The fifth group was selected as a negative control group (non-immunized). The virulent RH strain of Toxoplasma gondii was used to challenge. Delayed-type hypersensitivity responses (DTHs) were measured by intra-footpad injection measuring induration at timed intervals. Lymphocyte transformation tests (LTTs) were done on lymph node cells using [3H] thymidine incorporation as an indication of reactivity. Peritoneal macrophages from sensitized mice were stimulated and nitric oxide was measured by Griess method. The ESA-F(1) and ESA-F(2) fractions were separated on poly acrylamide gel electrophoresis (PAGE) and SDS-PAGE. ESA-F(1) had 4 bands on PAGE and 14 bands on SDS-PAGE. ESA-F(2) had one band on PAGE and two bands on SDS-PGE. Sensitized mice showed DTH and lymphocyte transformation responses to total-ESA, ESA-F(1), and ESA-F(2) and peritoneal macrophages produce nitric oxide following stimulation. In challenge experiments, all non-immunized mice died within 10 days, whereas immunized mice survived for longer time periods (P<0.05). The highest survival rate was observed in mice that immunized with ESA-F(2). We suggest that these antigens especially ESA-F(2) should be of value for the development of new strategies for immunization against toxoplasmosis.
Daryani
Ahmad
A
Ardabil University of Medical Sciences, Ardabil Province, Iran. daryanii@yahoo.com
Hosseini
Ahmad Zavaran
AZ
Dalimi
Abdolhossein
A
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology* / Q000494:pharmacology; D005591:Chemical Fractionation; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007114:Immunization / Q000379:methods*; D008213:Lymphocyte Activation / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000276:immunology / Q000378:metabolism; D016052:Protozoan Vaccines / Q000276:immunology* / Q000592:standards; D016019:Survival Analysis; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000276:immunology* / Q000517:prevention & control
D000953:Antigens, Protozoan; D016052:Protozoan Vaccines; D009569:Nitric Oxide