Inactivation of human and avian influenza viruses by potassium oleate of natural soap component through exothermic interaction

PLoS One. 2018 Sep 27;13(9):e0204908. doi: 10.1371/journal.pone.0204908. eCollection 2018.


An influenza epidemic is still a problem despite the development of vaccines and anti-influenza drugs. Preventive measures such as handwashing are fundamental and important for counteracting influenza virus infection. In this study, we clarified the anti-influenza virus effects of surfactants, which are the main components of hand soaps for hand washing: potassium oleate (C18:1), sodium laureth sulfate (LES) and sodium lauryl sulfate (SDS). For a human influenza virus strain (H3N2), C18:1 reduced the infectivity by 4 logs or more, whereas LES and SDS reduced the infectivity by 1 log or less. Similar results were obtained when an avian influenza virus strain (H5N3) was used. The interaction between the surfactant and virus was then investigated by isothermal titration calorimetry. The LES-virus system showed a positive value of enthalpy changes (ΔH), meaning an exothermic interaction that indicated a hydrophobic interaction. In contrast, both the C18:1-virus system and the SDS-virus system showed negative values of ΔH, meaning an endothermic interaction that indicated an electrical interaction. The ΔH value of the C18:1-virus system was much higher than that of the SDS-virus system. A mixture of C18:1 and HA proteins similarly showed negative values of ΔH. These results indicate that influenza virus inactivation by a hydrophobic interaction of a surfactant with the viral envelope is insufficient to prevent infection, whereas inactivation by an electrical interaction of a surfactant with HA proteins is sufficient to prevent influenza virus infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chick Embryo
  • Chickens
  • Dogs
  • Humans
  • Influenza A Virus, H3N2 Subtype / chemistry*
  • Influenza A Virus, H5N8 Subtype / chemistry*
  • Influenza in Birds / prevention & control
  • Influenza, Human / prevention & control
  • Madin Darby Canine Kidney Cells
  • Oleic Acid / chemistry*
  • Soaps / chemistry*
  • Sodium Dodecyl Sulfate / analogs & derivatives
  • Sodium Dodecyl Sulfate / chemistry
  • Virus Inactivation*


  • Soaps
  • Oleic Acid
  • Sodium Dodecyl Sulfate
  • sodium laureth sulfate

Grant support

The funder (Shabondama Soap Co., Ltd.) provided support in the form of salaries for TK but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section.