Novel Antiviral—Griffithsin Derived from Algae—for Prophylaxis or Treatment of Rabies Infection

Rabies virus (RABV) infection leads to fatal encephalitis—inflammation of the brain—if left untreated. Millions of people survive RABV infection each year due to timely administration of post-exposure treatment, however, nearly 60,000 people die from rabies each year according to the World Health Organization. Obstacles to timely treatment for RABV infection include the high cost and burdensome storage requirements (i.e., refrigeration) of current post-exposure treatments (i.e., rabies immunoglobulin (RIG)).

CDC tested a broad-spectrum antiviral from a protein found in red alga, Griffitshia sp., that offers a low-cost way to potentially prevent or treat infections from rabies virus. Researchers determined that Griffithsin (GRFT) neutralizes rabies virus (RABV) activity in vitro and in vivo. Currently, with the exception of RIG and another international monoclonal antibody-based product, no other antiviral compounds have approvals for prophylaxis or treatment of rabies infection.

In CDC experiments, 100% of hamsters treated initially with one dose of GRFT, in combination with four dose of rabies vaccine, survived when challenged with a high dose of rabies virus 28 days later. GRFT also has some effect against rabies virus when used alone and can potentially replace RIG for rabies post-exposure therapeutics.

Manufacturers have already recombined and mass-produced GRFT as a biological active compound in E. coli and tobacco plants which could make this an easy to manufacture and low-cost antiviral. Lastly, GRFT has high thermostability with a melting temperature of 80°C/176°F so it can remain stable if cold chain interruptions occur during transportation or storage. This characteristic makes it ideal for rural areas.