Poster

  • P035

EVALUATION OF THE IMMUNE RESPONSE AGAINST THE FORMATION OF TISSUE CYST OF Toxoplasma gondii IN PIGS IMMUNIZED WITH DNA+sag1+rop18 VACCINE.

Presented in

Poster Session I

Poster topics

Authors

Professor João Luís Garcia (Lavras / BR), Rafaela M. B. Jurkevicz (Londrina / BR), Ana C. Cavallieri (Londrina / BR), Andressa C. Moreira (Londrina / BR), Milena Patzer Rose (Londrina / BR), Ana Flávia Minutti (Londrina / BR), João Pedro Sasse (Londrina / BR), Ana C. dos S. Silva (Londrina / BR), Ana P. M. Candeias (Londrina / BR), Professor Luiz Daniel de Barros (Lavras / BR)

Abstract

Toxoplasma gondii is an obligatory intracellular protozoan that affects all homeothermic animals and humans. Pork-containing cysts are considered one of the most important routes of transmission to humans. Vaccination of domestic animals, aiming to reduce the number of tissue cysts, may be one of the strategies for controlling T. gondii. The objective of the work was to evaluate the animals' immune response and protection against the formation of tissue cysts in pigs immunized with a DNA vaccine encoding sag1 and rop18. Twelve crossbreed pigs were used, divided into three groups (n=4), animals from G1 received pcDNA 3.1 + sag1+ rop18 (300µg) intramuscularly, while animals from G2 (n=4) received pcDNA 3.1 + sag1+ rop18 ( 300µg) via the intradermal route, and the G3 animals received only pcDNA 3.1 (300µg, two animals via the intramuscular route and two via the intradermal route). Four doses were made every 14 days, and blood samples were collected for Enzyme Immunosorbent Assay (ELISA) at the same dose interval, 15 days after the challenge and on the day of euthanasia. Fourteen days after the last dose, the challenge was carried out with 3x103 oocysts of strain ME49 orally. Thirty days after the challenge, the animals were euthanized and a pool of muscles (masseter, tongue, heart, and diaphragm) were used for bioassay in mice. One animal from G2 died before the challenge due to other causes. The bioassay showed that 6/12 (50%), 6/9 (66.6%), and 10/12 (83.3%) of the mice were positive for groups G1, G2, and G3, respectively, and the mean number of brain cysts was 513; 586; 634; for G1, G2, and G3, respectively. There was no statistical difference between G1 x G2 (p=0.34), G1 x G3 (p=0.22), and G2 x G3 (p=0.37). Although there are no statistical differences, effectiveness in reducing the number of tissue cysts by 38% in G1 and 20% in G2 was observed. The ELISA demonstrated an increase in the humoral immune response before the challenge for IgG and IgM, with a better response for the group immunized via the intramuscular route. These data show the importance of studying possible T. gondii proteins as antigens to achieve adequate protection against the formation of tissue cysts in pigs, one of the main routes of transmission of this zoonosis to humans.

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