A new study published by Prof. Biao He et al in the Journal of Virology suggests that a rabies vaccine in development could reverse the progression of the disease even after it has taken root in the central nervous system (CNS).
He and his University of George colleagues published the paper, entitled "Parainfluenza virus 5 expressing the G protein of rabies virus protected mice after rabies virus infection," in the December 2014 issue of the journal. A Science Daily article summarizing the findings aptly described traditional rabies therapies as a "race against the clock," as post-exposure prophylaxis must be administered in a critical period before the virus infiltrates the brain.
In contrast, the new vaccine, caused reversal of rabies which had progressed to the CNS in 50% of tested mice. The key innovation of this new rabies vaccine is its use of the innocuous (to humans) virus PIV5 (parainfluenza virus 5) as a vehicle for the delivery of the rabies G protein. When this particular protein is presented to the immune system, antibodies to this antigen are more rabidly produced.
Researchers explained that this represents an improvement over the weakened and modified rabies virus currently administered to patients. Importantly, the new vaccine only contains the antigen that catalyzes immune response, so risk of vaccine complications is much lower.
The efficacy of this vaccine in human patients remains to be seen.