Abstract:
Since its establishment in 1908, the Onderstepoort Veterinary complex has developed more than
50 veterinary vaccines that have been used over the period in the control of animal viral and
bacterial diseases in Southern Africa and elsewhere around the world. These vaccines have been
either live attenuated or inactivated. The inactivated vaccines are generally formulated with an
aqueous or an oil adjuvant. Onderstepoort oil-adjuvanted vaccines have been formulated with the
old Freund’s formulation, using surfactants that are not always compliant with current regulatory
requirements. Other disadvantages associated with use of the traditional Freund’s formulation
include safety in vaccinated animals, unavailability of certain reagents or components, as well as
their impact to the cost of the final vaccine.
The present study was designed to assess four oil-adjuvanted Onderstepoort vaccines, i.e. the E.
coli, the enterotoxaemia or Pulpy kidney, the Vibrio or Campylobacter fetus and the Infectious
coryza vaccines. The first three vaccines are formulated with a surfactant that is no longer readily
available and is not registered by regulatory authorities, while the surfactant used in the
Infectious coryza vaccine tends to result in adverse reactions in vaccinated chickens. The
traditional liquid paraffin Marcol was compared to two new liquid paraffin white oils (PFP8 and
PFP14), while the traditional emulsifiers Cirrasol EN-MP® and Arlacel® were compared to two
new products, Montanide 103™ and Simulsol-P2®. In addition, Cirrasol EN-MP® was compared
to Arlacel®, given the fact that the latter is an approved emulsifier for use in animal vaccines.
Two ready-to-use emulsifiers, i.e. Montanide™ ISA 70 VG and Montanide™ ISA 206, were
also tested with the Infectious coryza vaccine. The three liquid paraffins and four surfactants were evaluated for their physical characteristics,
as well as their ability to generate a safe and effective vaccine when formulated with the above
four vaccine antigens. The safety and efficacy of the different formulations were evaluated in
both laboratory animals and target animals, i.e. sheep, cattle and chicken. The results obtained
can be summarized as follows. (i) The two new liquid paraffins had similar physical
characteristics as the traditional Marcol, and they also did not cause adverse reactions in
vaccinated animals; (ii) Simulsol-P2® displayed a poor ability to form a stable emulsion for the
above vaccines; (iii) Montanide 103™ was stable and was safe in most of the vaccines, but
caused persistent local reactions in the E. coli vaccine; and (iv) the Arlacel® formulations were
stable, safe and showed better immunogenicity profiles as compared to the other formulations.
