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Inactivated whole virus vaccines against FMD are formulated as mono- or polyvalent products with suitable stabilisers, buffers and adjuvants to enhance their potency.
In aqueous formulations, the inactivated viral antigen is adsorbed onto
Al(OH)3 and further adjuvanted with saponin. Such vaccines
are used successfully world-wide for the immunisation of ruminants. However,
commercial aqueous vaccines have not been successful in immunising pigs
and concentrated, inactivated antigens formulated as oil-adjuvanted vaccines
have been used widely in this species. Oil-adjuvanted FMD vaccines are
also used in cattle, more particularly in South America (Casas
Olascoaga, 1978), and improved formulations have reduced the local
reactions initially seen in this species. Advantages are claimed for the
use of oil-adjuvanted FMD vaccines in cattle in the areas of duration
of immunity and the ability to immunise calves in the face of maternal
immunity (Sadir et al., 1988).
Simple water-in-oil preparations can be made by the emulsification of
the antigen in aqueous solution with light mineral oil and an emulsifying
agent. Alternatively, a more easily injectable formulation can be made
by further emulsification in a second aqueous phase to produce a stable
water-in-oil-in-water emulsion (DOE). There are several reports of the
successful experimental use of these DOE FMD vaccines in cattle and pigs
(Barteling et al., 1990; Doel
et al., 1994) and commercial DOE vaccines are now available from some
manufacturers.
Preservatives are added to each formulation to prevent contamination in multi-dose vaccine bottles.
Some vaccine viruses are very much more effective on a weight-for-weight
basis than others (there are even significant differences between strains
of the same serotype), and such immunodominant strains are of great value
because of their ability to generate a high quality response against field
variants.
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