Resposta imune de suínos imunizados pela via nasal com proteínas de roptrias do Toxoplasma gondii


IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia




Toxoplasma gondii is an obligate intracellular parasite that infects a wide range of hosts including human beings. Herbivores are the main domestic infection sources for humans, and pork is considered the most important route of transmission. Recent decades have witnessed a great increasing in the number of technologies and immunological research to produce new vaccines. However, only one commercial vaccine (Toxovax, launched in 1992) for use in sheep is available in the UK. However, it is infective for humans, expensive, and has a short shelf-life. The development of non-infective vaccines such as subunit vaccines, DNA vaccine, as well as vaccination with recombinant proteins of T. gondii, should be encouraged. This study aims to evaluate the humoral and cellular immunity in pigs immunized intranasally with T. gondii rhoptry protein plus Quil-A. The rhoptries were obtained from the mechanical disruption of T. gondii tachyzoites of LIV-5 strain and subsequently separated by sucrose gradient. We used 13 crossbred pigs, divided into three groups, G1 (n = 6) received rhoptry proteins (200 µg) associated with Quil-A (50 µg), G2 (n = 4), and G3 (n = 3) which received Quil -A (50 µg) and PBS, respectively. All treatments were administered by nasal route on days 0, 21 and 42. On day 49, two animals from G1 were euthanized. Blood and mesenteric lymph nodes (LNM) were collected for evaluation of cellular immunity, through the test of lymphocyte proliferation and the other animals this study were challenged with 103 infective oocysts of the VEG strain. Clinical signs and temperature were analyzed before and after challenge. The humoral response (IgG and IgM) was evaluated on days 0, 21, 42, 49, 64, 79 using indirect immunoenzymatic test (ELISA). The presence of cysts in the brains of pigs was analyzed by bioassay in mice. The only clinical sign was fever observed in pigs from the 6th to 8th day after challenge. Five out of six animals from G1 had antibodies above cut-off at challenge day. Three from these five animals had both IgM and IgG responses, however, two animals showed just IgM response. There was a greater proliferation against T. gondii rhoptry proteins in lymphocytes collected from LNM compared to the blood cells. Partial protection against tissue cysts formation was observed in G1 compared to G3. The protection factors were 41.6% and 6.5% in G1 and G2, respectively. In conclusion, the animals were stimulated in part in humoral immune response, however, gave encouragement to the cellular immune response both locally and systemically.


suíno - toxoplasmose toxoplasmose - vacina toxoplasma gondii resposta imune swine toxoplasmosis toxoplasmosis vaccines veterinary immunology imunologia veterinária

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