Appeal No. 2002-2209 Page 4
Application No. 08/137,168
usually employing ammonium sulphate to precipitate the globulin fraction
and in some cases this is the form of the final product. Since antivenoms
in this form can give rise to severe serum reactions, it is known to employ
pepsin digestion to remove the Fc part of the immunoglobulin which is
primarily responsible for such immunogenic reactions.
Id., paragraph bridging pages 5 and 6.
In considering the issues raised in this appeal, it is important to distinguish
between monospecific antivenoms that are raised against single venoms and a
polyspecific antivenom which has been raised against the spectrum of different venoms.
As explained:
In general, the more specific an antivenom the greater the likelihood
that it will neutralise the challenging venom. Monospecific antivenom,
raised against single venoms, are therefore most effective against their
homologous venom. However, such antivenoms are only of use in the
treatment of a snake bite when the species or subspecies of the offending
snake has been identified. When the offending snake has not been
identified, as is usually the case in a “field” situation, a polyspecific
antivenom, raised against a spectrum of different venoms, is preferred in
order to improve the likelihood of the antivenom being effective against the
venom of the unidentified snake. Conventional polyspecific antivenoms,
however, lack the specificity of monospecific antivenoms and are,
therefore, less effective in neutralising the pharmacological activity of a
venom.
Id., page 6, last paragraph.
The nature of snake venom and snake antivenom is further explained as follows:
Snake venoms are complex multicomponent mixtures of protein,
nucleotides and metal ions. These components differ in molecular weight,
in their degree of antigenicity and in their concentration in the venom.
When venom is injected into an animal to raise an antiserum a number of
antibody populations may be produced. The concentration and affinities
of the antibodies raised will vary according to various criteria, for example,
the number of epitopes on the surface of a component, the immuno-
genicity of each epitope, the concentration of each component. The
lethal, neurotoxic components of venoms (including, for example,
rattlesnake venoms) often comprise low molecular weight, poorly
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