Preclinical evaluation of single domain antibody efficacy in mitigating local tissue damage induced by Bothrops snake envenomation

In a previous study the VHH KC329718 showed neutralization capacity against the myotoxicity triggered by the toxins BthTX-I, BthTX-II and B. jararacussu venom in a pre-incubation assay, encouraging the analysis of the neutralizing potential of VHH when it administrated 30 min after experimental envenoming. The neutralization of local damage by VHH KC329718 was evidenced by 28% reduction in leukocyte influx promoted by BthTX-I, in addition to a significant reduction in the levels of CK and LDH released by both the BthTX-I and BthTX-II toxins, and by B. jararacussu venom. By carrying out histological analysis, it was also possible to demonstrate a reduction in myonecrosis caused by the venom after treatment with VHH KC329718. These results demonstrate the high potential of VHH KC329718 against snakebite. [Display omitted] •Anti-PLA2 VHH KC329718 reduces the myotoxicity induced by B. jararacussu venom.•The VHH KC329718 reduce myotoxic effects not only from BthTX-I but also BthTX-II.•The histological evidence indicates a reduction in tissue damage by VHH KC329718. Camelid single-domain antibodies (VHH) represent a promising class of immunobiologicals for therapeutic applications due to their remarkable stability, specificity, and therapeutic potential. To enhance the effectiveness of antivenoms for snakebites, various methods have been explored to address limitations associated with serum therapy, particularly focusing on mitigating local damage and ensuring sustainable production. Our study aimed to characterize the pharmacological profile and neutralization capacity of anti-Phospholipase A2 (PLA2) monomeric VHH (Genbank accessions: KC329718). Using a post-envenoming mouse model, we used intravital microscopy to assess leukocyte influx, measured CK and LDH levels, and conducted a histopathology analysis to evaluate VHH KC329718′s ability to neutralize myotoxic activity. Our findings demonstrated that VHH KC329718 exhibited heterogeneous distribution in muscle tissue. Treatment with VHH KC329718 reduced leukocyte influx caused by BthTX-I (a Lys-49 PLA2) by 28 %, as observed through intravital microscopy. When administered at a 1:10 ratio [venom or toxin:VHH (w/w)], VHH KC329718 significantly decreased myotoxicity, resulting in a 35–40 % reduction in CK levels from BthTX-I and BthTX-II (an Asp-49 PLA2) and a 60 % decrease in CK levels from B. jararacussu venom. LDH levels also showed reductions of 60%, 80%, and 60% induced by BthTX-I, BthTX-II, and B. jararacus