Desenvolvimento de vacina de liberação controlada contra C. botulinum tipo c e tipo d utilizando quitosana

Abstract

Single shot vaccines against animal botulism were formulated, using chitosan microspheres prepared through simple coacervation as a controlled release matrix (adjuvant). Partially purified types C and D botulinic toxoids were employed as vaccine antigens and were obtained after the formaldehyde inactivation of native toxins. The prepare of the single shot vaccines was carried out following specific procedures and the antigen encapsulation efficiency was determined, using Bradfords total protein quantification method. Single shot vaccines were compared with control vaccines, adjuvanted with aluminum hydroxyde, in terms of potency and safety, according to quality criteria present of the Brazils Ministry of Agriculture, Animal Husbandry and Food Supply (MAPA). The encapsulation yield of the proposed technique reached 41,03% and 32,30% for types C and D botulinic toxoids, respectively. Control vaccines were approved accoording to the MAPA requirements, showing type C antitoxin titres ranging from 10 to >20UI/mL and type D antitoxin titres varying from 2 to 5 UI/mL, remembering that the official requirements are 5 and 2 UI/mL to type C and D antitoxin titres, respectively. Two of three single shot vaccines were approved, with type C antitoxin titres of 10UI/mL and type D antitoxin titres of 2 UI/mL. All vaccines, either control or single shot, were approved in relation to safety tests, because animals did not show any adverse reactions or residual toxicity related to the vaccination. The results obtained show that the chitosan microspheres controlled release system used to produce botulism vaccines is able to generate neutralizing antibodies against types C and D botulinic toxoids, besides being safe.