Antigenic relationships of fractionated western diamondback rattlesnake (Crotalus atrox) hemorrhagic toxins and other rattlesnake venoms as indicated by monoclonal antibodies.

Seven hemorrhagic factors have been isolated from Crotalus atrox venom, but their antigenic relationships have not been well studied. In this study, two different monoclonal antibodies, C. atrox peak 8 (CA-P-8) and C. atrox subclone 5 (CA-5+), were produced against two C. atrox venom hemorrhagic fractions and used in an ELISA (enzyme-linked immunosorbent assay) to determine if the hemorrhagic factors in C. atrox venom are antigenically related. The same ELISA test was used to determine cross-reactivity of seven other crude Crotalidae venoms. The two monoclonal antibodies were tested for their ability to neutralize each hemorrhagic HPLC fraction separated from C. atrox venom. C. atrox venom was fractionated into 22 fractions using HPLC analytical DEAE ion exchange. Fractions 4-17 were hemorrhagic. The CA-P-8 monoclonal antibody reacted strongly with hemorrhagic fraction 8; CA-5+ had a broader reactivity and reacted with several HPLC hemorrhagic and non-hemorrhagic fractions. Crude venoms of C. adamanteus, C. scutulatus scutulatus and C. viridis lutosus reacted with CA-P-8, while C. viridis lutosus, C. viridis oreganus, C. scutulatus scutulatus and C. horridus horridus reacted with CA-5+. C. molossus molossus and C. lepidus lepidus did not react with CA-P-8 and CA-5+. Hemorrhagic HPLC fractions 6, 7, 8, were completely neutralized by monoclonal antibody CA-P-8; fraction 9 was partially neutralized. The present study indicated that some C. atrox venom HPLC hemorrhagic fractions have both common and unique epitopes. Antigenic determinants were also found to be shared among different Crotalus species.(ABSTRACT TRUNCATED AT 250 WORDS)