The effectiveness of the chemical disinfectants benzalkonium chloride (BAC) and monochloramine was tested on bacteriophages MS2, P22, PhiX174, and Phi6. BAC is a quaternary ammonium compound (QAC). QACs are commonly used in household disinfectants, and they are the active ingredient in over 200 disinfectants currently recommended by the EPA to inactivate COVID-19. QACs are membrane active agents, which means that they are surfactants that interrupt cell membranes, or in the case of viruses, their envelopes. Phi6, the enveloped bacteriophage that was tested, was much more susceptible to BAC disinfection than the other, non-enveloped viruses. PhiX174 was very resistant to BAC, which may be caused by spike proteins on its capsid. Monochloramine has become a more popular chemical disinfectant because it does not produce chlorinated disinfection byproducts such as trihalomethanes and haloacetic acids Monochloramine can react with various biomolecules like proteins, enzymes, and DNA to result in the oxidation and modification of these critical components. MS2 was much more resistant to monochloramine disinfection than the other bacteriophages. PhiX174 was one of the most susceptible phages to monochloramine, but was very resistant to BAC. The differences in virus susceptibility amongst the chemical disinfectants may derive from a combination of the disinfectant’s primary germicidal mechanism and the virus structure (e.g., protein spikes or differences in genome).
