russelii venom ( Fig  4B) The VAV assay will only detect bound a

russelii venom ( Fig. 4B). The VAV assay will only detect bound antivenom because the microplate is coated with an anti-snake venom antibody which binds the venom, and detection is with labelled anti-horse antibodies which bind equine antivenom (Fig. 1B). In vitro this provides

a measure of antivenom-venom binding for increasing concentrations of antivenom. The curve increases with increasing binding of antivenom (antibodies) to free venom until a point where increasing amounts of antivenom (antibodies) prevent the venom-antivenom complex binding to the microplate, because there are no longer any free antibody binding sites (epitopes) on the venom molecules ( Fig. 1B). The concentration of antivenom at which the VAV peak occurs is the concentration

at which every venom component, on average, must be attached to at least one antivenom molecule. This gives us a new measure SP600125 datasheet of antivenom efficacy. In addition, it provides an assay to measure bound venom in vivo and to determine if venom detected post-antivenom selleck chemical using the free venom assay is bound. At low concentrations of antivenom, the antivenom binds to the venom molecules in a one to one ratio to form VAV complexes. The VAV complex still has free binding sites on the venom molecule which allows further antivenom to bind with increasing concentrations to form V(AV)2, V(AV)3, … V(AV)n where n is the maximum number of antibody binding sites on a venom molecule. However, at least one binding site must remain free and exposed for the venom-antivenom complex to bind to the anti-snake venom antibodies on the microplate. In other words, V(AV)n cannot bind to the microplate ( Fig. 1B). This is the reason that initially as the antivenom concentration increases and the proportion of antivenom in the mixture increases, there is an increasing amount of VAV detected. The maximum or VAV

peak occurs when further binding of antivenom results in decreasing free antibody binding sites on venom molecules, resulting in decreasing binding to the microplate. Rather simplistically, the VAV peak is when there is on average of mainly V(AV)n − 1 in the antivenom/venom mixture and this means that there is at least one antivenom molecule is attached to each venom molecule. This is a rather simplistic description of what occurs the because venom consists of different toxins and each toxin is likely to have a different number of epitopes (antibody binding sites) depending on toxin size and antigenicity. In addition, antivenom is a polyclonal antibody mixture with antibodies to different toxins and different toxin epitopes with varying affinities. However, the stepwise formation of V(AV)k complexes (where 1 < k < n) applies to the behaviour of the whole population of venom (toxins) and antivenom molecules, regardless of the fact the venoms contain dozens of different proteins, each with several epitopes, and that the antivenoms are themselves polyclonal.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>