Basic
phospholipases A2 (PLA2) are toxic and induce a wide spectrum of pharmacological effects, although the acidic
enzyme types are not lethal or cause low lethality. Therefore, it is challenging to elucidate the mechanism of action of acidic
phospholipases. This study used the acidic non-toxic Ba SpII RP4 PLA2 from Bothrops alternatus as an
antigen to develop anti-PLA2
IgG antibodies in rabbits and used in vivo assays to examine the changes in crude
venom when pre-incubated with these
antibodies. Using Ouchterlony and western blot analyses on B. alternatus
venom, we examined the specificity and sensitivity of
phospholipase A2 recognition by the specific
antibodies (anti-PLA2 IgG). Neutralisation assays using a non-toxic PLA2
antigen revealed unexpected results. The (indirect) haemolytic activity of whole
venom was completely inhibited, and all catalytically active
phospholipases A2 were blocked.
Myotoxicity and lethality were reduced when the crude
venom was pre-incubated with anti-PLA2
immunoglobulins. CK levels in the skeletal muscle were significantly reduced at 6 h, and the muscular damage was more significant at this time-point compared to 3 and 12 h. When four times the LD50 was used (224 μg), half the animals treated with the
venom-anti PLA2
IgG mixture survived after 48 h. All assays performed with the specific
antibodies revealed that Ba SpII RP4 PLA2 had a synergistic effect on whole-
venom toxicity.
IgG antibodies against the
venom of the Argentinean species B. alternatus represent a valuable tool for elucidation of the roles of acidic PLA2 that appear to have purely digestive roles and for further studies on
immunotherapy and
snake envenoming in affected areas in Argentina and Brazil.