AN APPROACH FOR IMPROVEMENT OF THE FOWL CHOLERA ADJUVANTED VACCINE IN EGYPT PRIVATE

Reformulation of the local oil adjuvanted fowl cholera inactivated vaccine components, the nature of adjuvant and vaccinal antigen, was approached aiming to improve its protective efficacy in chickens. A substantial value of reformulation was verified by protection against challenge exposure to both virulent serotypes A and D of P: multocida and seroconversion was detected by indirect ELISA and indirect haemagglutination (IHA) assays. All vaccinal antigens comprised formalized cultures of P. multocida serotypes A:5, 8, 9 and D:2 emulsified in the currently used water-in-oil adjuvant (Span, Paraffin and Tween-80, SPT80) and/or a commercial oil- in-water adjuvant (EMC). Besides, use of non- formalin treated lysates of P. multocida as a novel vaccinal antigen was evaluated in parallel. The oil-in-water adjuvant (EMG) was preponderant when used, with and without the currently used water-in-oil adjuvant (SPT80) in all new vaccine formulations, producing a stable, more potent, less viscous emulsion and easy injectable product. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis revealed a considerable similarity in the electrophoretic patterns of cell lysates recovered from P. multocida serotypes A:5, 8, 9 and D:2, manifested as 14-16 protein bands and the molecular mass range of about 14- 190 kilodaltons. However, a considerable reduction in number of protein bands was observed in the cell lysates of their counterparts after formal- in treatment. All new vaccine formulations used in this study are found reliable for seroconversion and protection of vaccinated chickens, with variable effectiveness. Use of non-formalin treated lysates of P. multocida as a novel vaccinal antigen emulsified in EMG as an oil-in-water ad- juvant, provided an advantageous formulation of the fowl cholera vaccine that conferred a 100% protection of chickens against virulent challenge. Moreover, it became much more safer vaccine for chickens since it contains a pharmaceutical grade oil of EMG with no formalin residues. This work initiates a potential for production of safer bacte-rial vaccines for edible animals.