DISSERTATION: P.J. Spencer submitted this dissertation for the degree of Master of Science in Nuclear Technology publicly examined at the Department of Bioengineering of the Nuclear Energy Research Institute of the University of São Paulo, São Paulo, Brazil, in 1995.
Advisor: Professor José Roberto Rogero
ABSTRACT. Protein irradiation causes structural alterations which result in activity and function loss. This process has been useful in the detoxification of animal venoms and toxins, resulting in low-toxicity products with increased immunogenicity. Bothrops jararacussu venom behaves as a weak immunogen and its lethal activity is not neutralized by either autologous, heterologous or bothropic polyvalent antisera. This venom is markedly myotoxic and the commercial bothropic antiserum does not neutralize this activity because of the low immunogenicity of the myotoxins. Thus, the present work was carried out to evaluate the possibility of irradiating Bothrops jararacussu venom to increase immunogenicity of the myotoxic components leading to production of myotoxins neutralizing antibodies. Bothrops jararacussu venom samples were irradiated with 500, 1,000 and 2,000 Gy of 
Co gamma rays. A 2.3-fold decrease of toxicity was observed for the 1,000 Gy irradiated sample, while the 2,000 Gy irradiated sample was at least 3.7-fold attenuated. On the other hand, the 500 Gy dose did not promote any detoxification. Electrophoresis and HPLC data indicate that radiation led to the formation of high molecular weight products. The proteolytic and phospholipasic activities decreased in a dose-dependent manner, and the phospholipases were more resistant than the proteases. Both animal groups (rabbits) immunized with either native or 2,000 Gy irradiated venom produced native venom-binding antibodies, and a slightly higher titer was obtained in the serum of the rabbit immunized with the irradiated samples. Western blot data indicate that the anti-irradiated venom IgGs recognized a greater number of either autologous and heterologous venom bands, and both sera behaved as genus specific.The anti-native serum did not neutralize the myotoxic activity of native venom, while the anti-irradiated venom was able to neutralize this activity.
CORRESPONDENCE TO:
P. J. SPENCER - Departamento de Bioengenharia, TBR, Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, Travessa R, 400, Cidade Universitária, CEP 05508-900, São Paulo, SP, Brasil.
Publication Dates
-
Publication in this collection
08 Jan 1999 -
Date of issue
1996
