Arginine-enveloped virus inactivation and potential mechanisms

Arginine synergistically inactivates enveloped viruses at a pH or temperature that does little harm to proteins, making it a desired process for therapeutic protein manufacturing. However, the mechanisms and optimal conditions for inactivation are not fully understood, and therefore, arginine viral inactivation is not used industrially. Optimal solution conditions for arginine viral inactivation found in the literature are high arginine concentrations (0.7-1 M), a time of 60 min, and a synergistic factor of high temperature (≥40°C), low pH (≤pH 4), or Tris buffer (5 mM). However, at optimal conditions full inactivation does not occur over all enveloped viruses. Enveloped viruses that are resistant to arginine often have increased protein stability or membrane stabilizing matrix proteins. Since arginine can interact with both proteins and lipids, interaction with either entity may be key to understanding the inactivation mechanism. Here, we propose three hypotheses for the mechanisms of arginine induced inactivation. Hypothesis 1 describes arginine-induced viral inactivation through inhibition of vital protein function. Hypothesis 2 describes how arginine destabilizes the viral membrane. Hypothesis 3 describes arginine forming pores in the virus membrane, accompanied by further viral damage from the synergistic factor. Once the mechanisms of arginine viral inactivation are understood, further enhancement by the addition of functional groups, charges, or additives may allow the inactivation of all enveloped viruses in mild conditions.