Quantitative analysis of parasite DNA in the blood of immunized and naïve mice after infection with Neospora caninum

• Published in: Parasitology Vol. 135; no. 2; pp. 175 - 182
• Main Authors: PINITKIATISAKUL, S., MATTSSON, J. G., LUNDÉN, A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.02.2008
• Subjects: Animals; Antibodies, Protozoan - analysis; Antibodies, Protozoan - metabolism; Antigens, Protozoan - immunology; Antigens, Protozoan - metabolism; Antigens, Surface - immunology; Biological and medical sciences; Body Weight; brain; Brain - parasitology; Coccidiosis - immunology; Coccidiosis - parasitology; disease severity; DNA; DNA, Protozoan - analysis; Female; Fundamental and applied biological sciences. Psychology; General aspects; General aspects and techniques. Study of several systematic groups. Models; immune-stimulating complexes; immunity; immunization; Invertebrates; iscom; Mice; Mice, Inbred BALB C; NcSRS2; Neospora - immunology; Neospora caninum; neosporosis; parasitaemia; parasite load; parasitemia; polymerase chain reaction; Polymerase Chain Reaction - methods; protective effect; Protozoan Proteins - immunology; Protozoan Vaccines - immunology; quantitative analysis; real-time PCR; real-time polymerase chain reaction; recombinant antigens; recombinant vaccines; Specific Pathogen-Free Organisms; surface antigens; Time Factors; vaccine; Vaccines, Synthetic - immunology; vaccine; iscom; parasitaemia; real-time PCR; Neospora caninum; NcSRS2; Protozoa; Apicomplexa; Rodentia; Parasite; Vaccine; Blood; Infection; Polymerase chain reaction; Vertebrata; Mammalia; Mouse; DNA; Quantitative analysis
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182007003733

Real-time PCR was used to study the duration and level of parasitaemia in mice immunized with immune-stimulating complexes (iscoms) containing recombinant NcSRS2, one of the immunodominant surface antigens of Neospora caninum. After challenge infection, blood was collected daily for 9 days. During this period the amounts of parasite DNA detected in immunized mice were significantly lower (P<0·001), and the duration of parasitaemia appeared to be shorter, than in non-immunized controls. Furthermore, the degree of parasitaemia seemed to correlate well with the amount of N. caninum DNA in the brain 3 weeks post-inoculation and with disease severity measured as changes in body weight. These results indicate that the protective immunity induced by the NcSRS2-iscoms was sufficient to reduce the level of parasitaemia, which probably reduced the number of parasites reaching the brain, and could be the reason for the reduction in brain parasite load and clinical symptoms. Furthermore, real-time PCR was found to be a sensitive means for rapid assessment of N. caninum in blood.