Ronald Bastos Freire

Humoral immune response in cattle experimentally infested with larvae of Dermatobia Hominis

Six bovines were infested with 60 first instar larvae of Dermatobia hominis. The animals were bleed weekly, and their antibodies levels to D. hominis L1, L2 and L3 instars measured during the time, following the infestation course. The antisera were submitted to a titration against optimal dilutions of antigen coated wells of microplates, previously sensitized with L1, L2 and L3 preparations, respectively. The ELISA assay was used to test single dilutions of antisera, which results were comparatively analyzed with a control of not infested animals. Antibodies against L1 were detected between the first and 21st day post-infestation (DPI) and, from the 42nd DPI on. Anti-L2 antibodies, could be detected on the 21st DPI and from the 35th DPI until approximately the 49th DPI, when it was observed a decreasing of antibodies titration equivalent to the control group. No antibodies were detected against the L3 instar-antigens. Antibodies levels against L1 showed absorbance higher than 1.500 O.D. at 492nm in the ELISA assay, when compared to the 0.096 O.D. observed to the negative animals. High anti-L2 antibodies were also detected on the 21st DPI, where two animals showed O.D. of 0.450 and 0.900 at 492nm, with a cut-off estimated on 0.110 O.D. It was also demonstrated a rising of anti-L2 antibodies in the same four animals, which presented antibodies response against L1 instar. The obtained results, with an estimated prevalence of 50%, were comparatively evaluated, taking the double diffusion immunoassay precipitation test as a standard, and showed a concordance of 98%. The association between infestation and presence of specific antibodies was also discussed.

Dinâmica populacional de células mielóides durante o curso de inflamação crônica em camundongos C57BL/6 infectados com Toxoplasma gondii

Cells of the mononuclear and polymorphonuclear series were analyzed throughout the course of Toxoplasma gondii infections of C57 BL/6 female mice with chronic inflammatory foci. The animals were inoculated intraperitoneally with 90-100 parasitic cysts followed by subcutaneous implantation of cover glasses (after 4 days). The shift of leukocytes from the blood to the inflammatory focus, corresponding to a prolonged infiltration of myeloid cells, was measured in a time course of 20 days. A significant decline was observed in the mature polymorphonuclear cells in the blood and a concomitant development of a marked monocytosis. Infections with T. gondii in mice with chronic inflammatory foci resulted in dedication of the entire myeloid cells system to the generation of cells that were exported to combat the inflammation, which occurred in those places, and to the chronic infection itself. The shift in the normal proportions of cells and in cells of different degrees of maturity, suggesting that a blockade in the chemokines extruded to attract polimorphonuclear cells, might account to a large extent for the failure of immune responses commonly associated with Toxoplasma subclinical infections.

Elisa de captura com IgY para quantificação de acetato de lupeol em Vernonia scorpioides lam. Pers (asteraceae)

For the first time, a yolk immunoglobulins-based immunenzymatic assay (capture IgY-ELISA) was carried out to detect Lupeol acetate (LAc) from Vernonia scorpioides Lam. Pers (Asteraceae). Antibodies (IgY) against lupeol acetate (antiLAc antibodies) were raised in White Leghorn hens immunized with LAc conjugated to the bovine serum albumin (LAc-BSA). The anti-LAc antibodies were recovered by cleanup columns containing LAc-BSA coupled to sepharose. The capture IgYELISA efficacy was of 97% when the predictive indices of sensitivity and specificity were 99.0% and 95%, respectively. The lowest and highest detection limits were of 0.02µgg -1 and 10µgg -1 of plant extract, respectively. The strength of this method was attested by its high reproducibility (between 94.75% and 96.81%), and a low internal variation (4.22 ± 1.03%), under the described conditions.

Ocratoxina A, aflatoxina 81 e citrinina como agentes moduladores da produção de anticorpos em aves e mamíferos

O presente trabalho foi desenvolvido com o objetivo de demonstrar os efeitos causados pela associacao entre ocratoxina A,aflatoxina 81 e citrinina, sobre a resposta imunitaria adaptativa de aves e mamiferos, a fim de determinar se estas micotoxinaspoderiam levar a modulacao do sistema imune. A toxicidade relativa de cada micotoxina, bem como de suas associacoes, foideterminada em celulas esplenicas de galinhas e camundongos, onde se observou a secrecao primaria de anticorpos (lgM)contra eritrocitos de carneiro, apos quatro horas de exposicao as micotoxinas. Os ensaios foram realizados na presenca e naausencia de soro heterologo proveniente de animais adultos normais, a fim de determinar possiveis interacoes entre ocomplemento presente no soro, com a acao toxica das micotoxinas. Observou-se uma notavel depressao imunologica nosgrupos tratados com a associacao entre citrinina e aflatoxina 81, porem, na presenca de soro heterologo, houve umaimunoestimulacao. Os resultados sugerem uma possivel interferencia de fatores inespecificos, os quais estao presentes nosoro proveniente de animais adultos normais, cuja atividade poderia amenizar ou ate mesmo neutralizar a acaoimunomodulatoria das micotoxinas, sugerindo a possibilidade de imunoterapia.