Production and evaluation of recombinant antigens of the alpha-latrotoxin of the american black widow spider Latrodectus mactans.

¹Prud’homme, M., ²Vázquez, H., ³Estévez, J., ³Magaña, P., ²Paniagua-Solís, J., ¹Alagón, A. and ¹Stock, RP.

1 Instituto de Biotecnología-UNAM, Cuernavaca, México, 2 Laboratorios Silanes, México, 3 Instituto Bioclon, México.

The venom of the black widow spider (Latrodectusmactans) contains several very potent high molecular weight neurotoxins that cause neurotransmitter release, which are highly specific for vertebrates, or for insects, or for crustaceans. Alpha-latrotoxin (a-LTX) affects the secretion process only in vertebrate presynaptic endings, making it the agent responsible for the effects of envenomation (latrodectism) in humans. Clinical effects reported after a black widow spider bite include hypertension, breathing problems, muscle cramps and intense pain. To relieve these symptoms antivenom is generally used. There is an effective and highly purified equine F(ab)2-based antivenom available in Mexico which is very well-tolerated by patients. This antivenom is made by immunization of horses with whole venom obtained by electrical stimulation of the spiders, a process which is laborious, expensive and risky. Since a-LTX is the only protein in the venom that affects humans, the aim of this work was to produce a-LTX as a recombinant protein in order to replace the use of venom as antigen in the production of the antivenom.

To this end, we have cloned and sequenced the entire gene that codes for the a-LTX, and we have also expressed, in a bacterial system, the amino terminal domain (the first 453 amino acids of the mature protein). Using this recombinant protein with different immunization protocols to immunize rabbits and horses we were able to produce antibodies capable of conferring complete protection against the effects of the venom in mice.

Support : PAPIIT-DGAPA IN230203-2

Correspondence to: monicap@ibt.unam.mx