Immunological properties of notexin, a potent presynaptic and myotoxic component from venom of the Australian tiger snake Notechis scutatus scutatus.

Neutralizing antibodies were raised in mice against notexin, the most toxic phospholipase A2 (PLA2) from Notechis scutatus scutatus venom, without the necessity of detoxifying the toxin prior to immunization. Using a sensitive radioimmunoassay we demonstrated that anti-notexin antibodies recognized (i) the parent antigen, (ii) closely related isoforms of notexin and (iii) venoms from Notechis genus snakes. In contrast, they failed to recognize other purified PLA2 or PLA2-containing venoms from other origins. Substitutions or chemical modifications occurring in the C-terminal part of the polypeptide chain of notexin altered the binding affinity for antibodies, implying that this region constitutes an antigenic domain of notexin.