Pyrimethamine inhibits rabies virus replication in vitro

Area of Science:

• Virology
• Immunology
• Pharmacology

Background:

• Rabies virus causes fatal encephalitis in humans, with over 59,000 deaths annually, particularly in Asia and Africa.
• Post-exposure prophylaxis (PEP) is effective but not always accessible, and no treatment exists for clinical rabies.
• Current treatments for clinical rabies are lacking, highlighting the need for novel therapeutic strategies.

Purpose of the Study:

• To identify FDA-approved drugs that can inhibit rabies virus infection.
• To investigate the efficacy of pyrimethamine and its synergistic potential with ribavirin against rabies.
• To explore the mechanisms underlying pyrimethamine's antiviral activity and potential limitations.

Main Methods:

• Screening of 385 FDA-approved drugs against rabies virus.
• In vitro testing of pyrimethamine for rabies inhibition and synergy with ribavirin.
• In vivo testing of pyrimethamine in rabies-infected mice.

Main Results:

• Pyrimethamine demonstrated in vitro inhibition of rabies virus by targeting adenosine synthesis.
• A synergistic effect was observed between pyrimethamine and ribavirin in vitro.
• Pyrimethamine showed no efficacy in rabies-infected mice, potentially due to immune system interference.

Conclusions:

• Pyrimethamine is a potential candidate for rabies treatment, warranting further investigation.
• The drug's efficacy may be modulated by its interaction with the host's innate immune response.
• Further research is needed to overcome pyrimethamine's limitations for effective clinical application in rabies.