As the COVID-19 pandemic continues to spread throughout the world, more questions are arising regarding the mechanisms of transmission. To limit the spread of the virus, it is important to understand the implications of infectious versus inactivated SARS-CoV-2 viruses.
In a recent publication in Science of the Total Environment, W. Hong et al. reported an RT-qPCR assay assisted by SDS-propidium monoazide (PMA) for rapid detection of infectious SARS-CoV-2 viruses in PCR-positive samples. Traditionally used methods, such as RT-qPCR of viral RNA, and immunoassays for viral proteins, are unable to distinguish between infectious and inactivated viruses. In the SDS-PMA RT-qPCR assay, the photo-reactive PMA dye permeates into inactivated viruses only and interacts with the RNA, preventing it from being detected by RT-qPCR. The authors found that using this method, they were successfully able to detect as low as 8 plaque-forming units of infectious virus in the positive PCR samples. The PMA assisted assay used by the authors provides a culture-free method that has comparable results to the gold-standard plaque assay for detecting infectious SARS-CoV-2 virus. This improved determination method will be able to better facilitate control of SARS-CoV-2 transmission.
Using viability PCR for detection of infectious coronaviruses is an important step in studying modes of transmission of the virus as well as taking precautions to slow the spread of COVID-19.
Hong, W., Xiong, J., Nyaruaba, R., Li, J., Muturi, E., Liu, H., Yu, J., Yang, H., & Wei, H. (2021). Rapid determination of infectious SARS-CoV-2 in PCR-positive samples by SDS-PMA assisted RT-qPCR. The Science of the total environment, 797, 149085. Advance online publication. https://doi.org/10.1016/j.scitotenv.2021.149085