Anti-botulism single-shot vaccine using chitosan for protein encapsulation by simple coacervation.

The aim of the present study was to compare the potency and safety of vaccines against Clostridium botulinum (C. botulinum) type C and D formulated with chitosan as controlled release matrix and vaccines formulated in conventional manner using aluminum hydroxide. Parameters were established for the development of chitosan microspheres, using simple coacervation to standardize the use of this polymer in protein encapsulation for vaccine formulation. To formulate a single shot vaccine inactivated antigens of C. botulinum type C and D were used with original toxin titles equal to 5.2 and 6.2 log LD50/ml, respectively. For each antigen a chitosan based solution of 50 mL was prepared. Control vaccines were formulated by mixing toxoid type C and D with aluminum hydroxide [25% Al(OH)3, pH 6.3]. The toxoid sterility, innocuity and potency of vaccines were evaluated as stipulated by MAPA-BRASIL according to ministerial directive no. 23. Encapsulation efficiency of BSA in chitosan was 32.5-40.37%, while that the encapsulation efficiency to toxoid type C was 41,03% (1.94 mg/mL) and of the toxoid type D was 32.30% (1.82 mg/mL). The single shot vaccine formulated using chitosan for protein encapsulation through simple coacervation showed potency and safety similar to conventional vaccine currently used in Brazilian livestock (10 and 2 IU/mL against C. botulinum type C and D, respectively). The present work suggests that our single shot vaccine would be a good option as a cattle vaccine against these C. botulinum type C and D.

A study of the influence of pH and of dissolved oxygen concentration on BHK-21 cells growth

In a joint project of IPT (Instituto de Pesquisas Tecnológicas do Estado de São Paulo) and Vallée S.A., the growth of BHK-21 cells, used for the production of a vaccine against foot-and-mouth disease, was studied. The present work aimed the evaluation of the influence of and dissolved oxygen concentration on this growth. Assays were performed in a 2 L stirred bioreactor, with a BHK-21 cell line supplied by Vallée S.A. The culture medium contained glucose, several amino acids, vitamins and bovine serum. Seven experiments were performed, in which pH varied between 6.8 and 7.4, and the dissolved oxygen concentration between 2 and 60(per cent) of air saturation. The definition of optimal values was based on analysis of cell productivity and amounts of cells produced at the point at which the cultures attained maximal cell concentration. Optimal values for these paramenters were observed at pH 7.2 and 10 per cente dissolved oxygen concentration.