In-Use Stability and Functional Efficacy of a Monoclonal Antibody Cocktail (TwinRab™) for Rabies Post-exposure...

Area of Science:

• Immunology
• Virology
• Public Health

Background:

• Rabies causes significant global mortality, with India bearing a substantial burden.
• Limited availability of rabies immunoglobulins (RIGs) hinders effective post-exposure prophylaxis (PEP) in resource-limited settings.
• TwinRab™, a two-antibody monoclonal cocktail, was developed as a scalable alternative to plasma-derived RIGs.

Purpose of the Study:

• To evaluate the in-use stability of TwinRab™ under simulated field-use conditions.
• To assess the biological efficacy of TwinRab™ in a preclinical model.
• To determine TwinRab™'s potential as a field-adaptable PEP option.

Main Methods:

• In vitro: TwinRab™ dilutions were stored at room temperature and tested for neutralizing potency using the rapid fluorescent focus inhibition test (RFFIT).
• In vivo: TwinRab™ was administered to Syrian hamsters at 6 and 24 hours post-rabies virus challenge, with survival compared to human RIG (Kamrab).

Main Results:

• TwinRab™ retained neutralizing potency after dilution and ambient storage up to 24 hours.
• The 600 IU/mL batch showed no significant loss of activity; the 300 IU/mL batch had minor losses at higher dilutions.
• In vivo, TwinRab™ achieved 90% survival at 6 hours and 70% at 24 hours post-challenge, comparable to Kamrab.

Conclusions:

• TwinRab™ maintains stability and functional efficacy under simulated clinical practice conditions.
• Its thermostability and protective efficacy support its potential as a next-generation PEP alternative.
• TwinRab™ could improve PEP access in high-burden regions with limited cold-chain infrastructure.