Safety and results of challenge of weaned pigs given a temperature-sensitive mutant of Toxoplasma gondii.
Two experiments were conducted to examine the responses of weaned pigs to inoculation with tachyzoites of the temperature-sensitive mutant (TS-4) of Toxoplasma gondii. Experiment 1 was done to examine the safety of the TS-4 mutant in weaned pigs given a single inoculation. No clinical sign was observed in 2 pigs inoculated subcutaneously (s.c.) (group 1) or 4 pigs inoculated intravenously (group 2) with 5 x 10(5) tachyzoites. No lesion was observed in the tissues of pigs in group 1; 3 of 4 pigs in group 2 had focal areas of gliosis and lymphocytic perivascular infiltrates in their brains. One pig also had focal areas of lymphocytic infiltrates in hepatic portal triads. No stage of T. gondii was observed in the tissues of these pigs. The TS-4 mutant was not isolated in mouse bioassay from the tissues of the 6 pigs in experiment 1. Experiment 2 was done to determine if 2 inoculations s.c. with TS-4 tachyzoites would protect pigs against inoculation orally with T. gondii oocysts. Pigs were inoculated s.c. with 5 x 10(5) TS-4 tachyzoites (4 pigs, group 3) or Hanks' balanced salt solution (4 pigs, group 4) on days 0 and 14 postinoculation (PI) and orally challenged with 1 x 10(5) oocysts of the GT-1 isolate of T. gondii 30 days PI. Clinical response to oocyst inoculation was more severe in pigs in group 4. Rectal temperatures of pigs in group 3 were significantly (P < 0.05) lower than pigs in group 4 on days 3, 4, and 9 following inoculation with oocysts.(ABSTRACT TRUNCATED AT 250 WORDS)
Lindsay
D S
DS
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Alabama 36849-5519.
Blagburn
B L
BL
Dubey
J P
JP
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001921:Brain / Q000469:parasitology / Q000473:pathology; D005260:Female; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D016052:Protozoan Vaccines; D013552:Swine; D013553:Swine Diseases / Q000517:prevention & control*; D014122:Toxoplasma / Q000276:immunology* / Q000302:isolation & purification; D014124:Toxoplasmosis, Animal / Q000517:prevention & control*
D000913:Antibodies, Protozoan; D016052:Protozoan Vaccines