Venom toxins from non-immunizing but related snake species

Venom toxins from non-immunizing but related snake species refers to the complex mixture of proteins and peptides found in the venom of snakes that were not used as the primary immunogens during the manufacture of a specific antivenom (WHO, 2017). These toxins typically belong to conserved families such as phospholipases A2 (PLA2s), snake venom metalloproteinases (SVMPs), and three-finger toxins (3FTxs), which are responsible for the clinical manifestations of envenomation, including paralysis, hemorrhage, and tissue necrosis (Gutiérrez et al., 2017). The therapeutic relevance of these toxins lies in the phenomenon of ackslash"paraspecificity,ackslash" where an antivenom produced against one species can neutralize the toxins of a related species due to shared molecular epitopes (Casewell et al., 2020). In clinical practice, this allows for the use of regional polyvalent antivenoms to treat bites from a variety of snakes within a geographical area, even if every species' venom was not included in the immunization mixture. However, the efficacy of antivenom against these non-immunizing toxins is often lower than against the primary target species, requiring higher doses and increasing the risk of adverse reactions like serum sickness or anaphylaxis (Gutiérrez et al., 2017). Small molecule inhibitors, such as Varespladib for PLA2s or Marimastat for SVMPs, are also being explored as adjunct therapies because they can target these conserved toxin families across different species regardless of the immunizing venom (Lewin et al., 2016). Understanding the cross-reactivity of these toxins is crucial for improving the design of next-generation antivenoms and ensuring effective treatment in regions with high snake diversity.

Other names

Paraspecific venom toxinsCross-reactive snake toxinsHeterologous venom antigensNon-target venom proteins

Neutralization of toxic activity through antibody-mediated binding to functional epitopes or direct inhibition of enzymatic sites by small molecules (Gutiérrez et al., 2017; Lewin et al., 2016).