Evidence for hydrogen-deuterium exchange in viral particles

Heavy water (D₂O) could enhance thermostability of some viruses. However, the underlying mechanism is not clear. Here we report the development of a matrix-aided gas-isotope-ratio mass spectrometry method that allows direct determination of deuterium/hydrogen (D/H) ratio in D₂O-treated Japanese encephalitis virus (JEV), hepatitis A virus (HAV) and RNA from D₂O-treated HAV. The D/H ratio was expressed as δD_SMOW. Our experiments showed that δD_SMOW values increased significantly in D₂O-treated viral samples compared to normal controls, and increment in δD_SMOW of D₂O, treated viral samples was in a fine linear relationship with increment in amount of samples loaded in BSA matrix. Our experiments also indicated that increased δD_SMOW of D₂O-treated virus correlated well with its enhanced thermostability. The results suggested that hydrogen-deuterium exchange occurred in viral particles and its RNA structure as a result of D₂O-treatment. Furthermore, such exchange could cause changes in viral phenotype, such as enhanced thermostability.