Human antibody fragments specific forBothrops jararacussuvenom reduce the toxicity of otherBothropssp. venoms

Abstract

Approximately 20,000 snakebites are registered each year in Brazil. The classical treatment for venomous snakebite involves the administration of sera obtained from immunized horses. Moreover, the production and care of horses is costly, and the use of heterologous sera can cause hypersensitivity reactions. The production of human antibody fragments by phage display technology is seen as a means of overcoming some of these disadvantages. The studies here attempted to test human monoclonal antibodies specific to Bothrops jararacussu against other Bothrops sp. venoms, using the Griffin.1 library of human single-chain fragment-variable (scFv) phage antibodies. Using the Griffin.1 phage antibody library, this laboratory previously produced scFvs capable of inhibiting the phospholipase and myotoxic activities of Bothrops jararacussu venom. The structural and functional similarities of the various forms of phospholipase A2 (PLA₂) in Bothrops venom served as the basis for the present study wherein the effectiveness of those same scFvs were evaluated against B. jararaca, B. neuwiedi, and B. moojeni venoms. Each clone was found to recognize all three Bothrops venoms, and purified scFvs partially inhibited their in vitro phospholipase activity. In vivo assays demonstrated that the scFv clone P2B7 reduced myotoxicity and increased the survival of animals that received the test venoms. The results here indicate that the scFv P2B7 is a candidate for inclusion in a mixture of specific antibodies to produce a human anti-bothropic sera. This data demonstrates that the human scFv P2B7 represents an alternative therapeutic approach to heterologous anti-bothropic sera available today.

Engineering Venom’s Toxin-Neutralizing Antibody Fragments and Its Therapeutic Potential

“…The unique structure of HCabs may account for the report that camel antibodies should be less immunogenic, less likely to activate a complement and potentially safer. Despite these considerations, several studies have focused on the engineering of recombinant neutralizing antibody fragments directed against snake venoms [64,65,66,67]. Most consisted of the panning of human naive scFv-phage libraries (Griffin.…”

Recombinant antibodies against Iranian cobra venom as a new emerging therapy by phage display technology

“…Currently, antivenoms are manufactured from animal plasma, generally from horses and sheep, and administered as monovalent or polyvalent immunoglobulins, Fab or F(ab)2 fragments, but a range of adverse reactions are observed [ 29 , 30 ]. Phage display technology and the production of recombinant antibodies in bacteria, yeast, insect, and mammalian expression systems have the potential to overcome these contraindications [ 13 ] and studies of recombinant antibodies against venoms from snakes [ 31 , 32 ] and scorpions [ 33 , 34 ] show the feasibility of this approach. While phage display is usually applied to antibody discovery, other non-antibody scaffolds also can be considered for the design of anti-venoms [ 35 ].…”

Current research into snake antivenoms, their mechanisms of action and applications

“…These fragments may be useful in treating paralysis and local effects in envenoming, due to their high tissue penetration. Furthermore, to reduce the immunogenicity, human scFvs, instead of murine scFvs, have been successfully tested against venom toxins [67][68][69]. However, they have a shorter serum half-life in vivo [35], meaning they are likely to require repeat doses when used in humans.…”