Effect of rSAG-1(P30) immunisation on the circulating and tissue parasites in guinea pigs as determined by quantitative PCR.
The efficacy of immunisation with Toxoplasma gondii recombinant protein (rSAG-1) was evaluated in the guinea pig model. For the infectious challenge, two strains, namely, strain C56 (10,000 tachyzoites) and strain 76K (100 cysts), were used to infect a group of 32 guinea pigs each. The circulating, cerebral and pulmonary parasite loads were determined with the real-time polymerase chain reaction (PCR) after immunisation. With the C56 strain, immunisation showed high activity with a reduction of greater than 1 log of the circulating and tissue parasite loads. Thus, there was a significantly lower circulating parasite load in the rSAG-1 + adjuvant group (0.5+/-1.5 Eq parasites/ml) as compared to that in the control group (67+/-110 Eq parasites/ml; p<0.05). In the same manner, the cerebral parasite load was much lower in the rSAG-1 + adjuvant group (10+/-20 Eq parasites/g) than that in the control group (339+/-291 Eq parasites/g; p<0.01). On the other hand, with the 76K strain, the effect of immunisation was much less and that only on the pulmonary parasite load [p(lung)<0.05]. This could be due to the use of different strains and stages of the parasite and/or the difference in the route of administration for challenge. The quantitative PCR technique used has shown a good correlation with animal inoculation, and when associated with the guinea pig model, it seems to be a useful and reproducible technique for future vaccine studies.
Flori
Pierre
P
Laboratoire de Parasitologie-Mycologie, C.H.U. de Saint Etienne, Hôpital Nord, 42055, Saint-Etienne, cedex 2, France. pierre.flori@univ-st-etienne.fr
Tardy
Laëtitia
L
Jacquet
Alain
A
Bellete
Bahrie
B
Hafid
Jamal
J
Raberin
Hélène
H
Tran Manh Sung
Roger
R
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology*; D016054:DNA, Protozoan / Q000097:blood; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D007074:Immunoglobulin G / Q000097:blood; D008168:Lung / Q000469:parasitology; D018512:Parasitemia / Q000517:prevention & control; D016133:Polymerase Chain Reaction / Q000379:methods*; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D013687:Telencephalon / Q000469:parasitology; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology / Q000517:prevention & control*; D022223:Vaccines, Subunit / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology
D000276:Adjuvants, Immunologic; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C047168:SAG1 antigen, Toxoplasma; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic