Coated cross-species antibodies by mannosamine–biotin adduct confer protection against snake venom without eliciting humoral immune response

Passive immunization with cross-species antibodies triggers the patient's immune response, thereby preventing repeated treatment. Mannosamine–biotin adduct (MBA) has been described as a masking agent for immunogenic reduction and here, the immunogenicity and biological activity of MBA-coated horse anti-viper venom (hsIgG) were compared to those of uncoated or PEGylated hsIgG. In in vitro tests, hsIgG binding was not affected by MBA conjugation. The immune response to hsIgG-MBA was about 8-fold and 32-fold lower than to PEG-coated and uncoated hsIgG, respectively. In vivo, hsIgG-MBA showed efficient venom-neutralization activity. We thus demonstrate the feasibility of using MBA as a masking agent for passive immunization with cross-species antibodies.