If we’ve learned anything from this past year, it’s that not all viruses are created equal! There are some viruses that are much more resilient (and thus more deadly) than others. This is in large part due to their physical and genetic structure. Understanding whether a virus is enveloped or non-enveloped is an important factor to consider when we talk about things like kill times, chlorine concentrations, and disinfectant efficacy.
First, let’s cover the physical structure of a virus. The viral cell consists of genetic material (RNA or DNA) surrounded by a protein shell, similar to an egg. These proteins, also referred to as capsids, are arranged in specific geometric formations around the outside of the viral cell. The structural formations protect the virus and allow it to survive in hostile environments (such as your GI tract).
Some viruses are enveloped, meaning they contain an extra layer of phospholipids on top of their capsid shell. While it might seem logical that an extra layer of protection would make it HARDER to kill a virus, the reverse is actually true.
Enveloped viruses are easier to kill with disinfectants because their phospholipid layer is sensitive to denaturation by temperature and pH. Once that protective envelope is broken down, the viral material inside is exposed to the effects of the disinfectant. Furthermore, the qualities of the virus that make it infectious (fusion proteins) are contained in that envelope. Once it is destroyed, the virus is no longer able to reproduce.
Non-enveloped viruses, on the other hand, are more resistant to disinfectants. Their capsid layer is tough, allowing them to survive under harsher conditions. The fusion proteins that enable a virus to spread are also embedded within that capsid layer, making it difficult for the disinfectant to break in and inactivate the virus.
Think of it this way—if you walk around barefoot all the time, your feet naturally become tougher and less affected by the rough surfaces of the ground. However, if your feet are always protected by shoes, then you are more likely to be sensitive to rocks and thorns if you try walking with your bare feet.
The good news is that hypochlorous acid is effective against both enveloped and nonenveloped viruses. Strong oxidizing agents, such as hypochlorous acid, are considered to be most effective against non-enveloped viruses. This is because the hypochlorous acid molecule can oxidize the protein layers and attack the viral cell.
“The efficacy of disinfection decreases with an increase in pH, likely due to the decreased proportion of hypochlorous acid group present.” (View Research Journal, May 2020)
This statement corroborates our claim that hypochlorous acid is much more effective as a disinfectant than sodium hypochlorite, which naturally resides at a higher pH. Quaternary ammonium compounds and isopropyl alcohol are also less effective against non-enveloped viruses.
Lin, Q., Lim, J. Y. C., Xue, K., Yew, P. Y. M., Owh, C., Chee, P. L., & Loh, X. J. (2020). Sanitizing agents for virus inactivation and disinfection. View, 1(2). https://doi.org/10.1002/viw2.16