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Journal of Venomous Animals and Toxins

Print version ISSN 0104-7930On-line version ISSN 1678-4936

J. Venom. Anim. Toxins vol.6 n.2 Botucatu  2000 

The comparison between the humoral response and the neutralizing capacity of sheep serum inoculated with natural venom and Co60 irradiated venom from Crotalus durissus terrificus (Laurenti, 1768)



THESIS: D. P. Netto submitted her thesis for her Doctor of Philosophy degree in Clinic Veterinary Medicine publicly examined in the School of Veterinary Medicine and Animal Husbandry - Botucatu, São Paulo State University/Faculdade de Medicina Veterinária e Zootecnia - Botucatu – Universidade Estadual Paulista, SP – Brazil, in 2000.

Advisor: Prof. Dr. Pedro Luiz Bicudo



ABSTRACT. Crotalus durissus terrificus venom was irradiated with Co to investigate the effects of antigen-irradiation on antivenom production in sheep. Twelve sheep were divided in two groups of 6. One group received irradiated, while the other received natural venom. Three doses of antigen were given at monthly intervals. The toxic activity of the venom was assessed by LD50 in mice. Weekly blood samples were obtained to evaluate anti-crotalic serum titers by indirect ELISA, neutralization capacity, and serum potency. A complete blood count, plasma protein and fibrinogen concentration, and serum albumin and globulin were also determined. At the end of the experiment, the animals were challenged with ovine LD50, without clinical abnormalities. The irradiated venom toxicity was 4.4 times lower than the natural venom toxicity. Serum obtained from sheep inoculated with irradiated venom neutralized 14.6 DL50, while serum from sheep inoculated with natural venom neutralized 4.4 DL50. Serum from sheep that received irradiated venom was 5 times more potent. No clinical changes were observed in either group. In both groups, the animals developed an acute inflammatory response with increased leukocyte, neutrophil, and eosinophil count, and an increase in plasma fibrinogen, plasma protein, and serum globulin. Although non-significant, these changes were more pronounced in the natural venom group, thereby showing its higher toxicity. There was no statistical difference in the imunogenic response between the groups.
KEY WORDS: Crotalus durissus terrificus, irradiated crotalic venom, crotalic antiserum, antiserum neutralization, ELISA, ovine.



D. P. Netto – Universidade Estadual de Londrina, Departamento de Medicina Veterinária Preventiva, Centro de Ciências Agrárias, Campus Universitário, CEP: 86051-970, Londrina, Paraná, Brasil.

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