• The Science of Killing the COV-2 Virus

    Covid 19 test

    Posted on Apr 17, 2020

    Electron micrograph of COV-2 virus attaching and entering a cell. Note the surface proteins on the virus.

    The SARS-COV-2 virus (causing coronavirus disease 2019 (COVID-19) in very small respiratory droplets (smaller than 10-micron diameter) can persist in the air and can travel by local air currents before they drop to the ground. The COV-2 virus is shed by infected person’s respiration by coughing, sneezing and touching nose or mouth and then touching surfaces and can last for days:

    • Airborne: up to 3 hrs
    • Cardboard: up to 24 hrs
    • Plastic and stainless steel: up to 3 days

    However, like most biological moieties the virus needs hydration in order to maintain its protein structure for infectivity.


    To understand how to kill the COV-2 virus, we need to know the biochemistry and cell biology underlying the infection mechanism. The outer shell of the virus is made of protein protruding from the bilipid layer of the virus membrane. It is the structure of both these elements that are necessary for viral integrity. A hydration layer made of water molecules are loosely attracted to the protein in an ordered structure (clatherin coat type) through charged (electrostatic) interaction. When this water coat evaporates the protein structure is disrupted, (called desiccation). An everyday example is a tomato that withers and wrinkles over days as the water and other molecules evaporate, causing proteins and other structures to denature. That is why the virus is inactivated more quickly when it is on cardboard compared to stainless steel or plastic surfaces. The cardboard wicks away the water molecules in three dimensions thereby drying out the virus. The stainless steel or plastic only allows for the water to evaporate in a two-dimensional geometry which takes longer. So, what happens to the protruding viral protein? As the water disappears, the protein three-dimensional structure (tertiary  conformation), which is important to the virus bioactivity, changes (it denatures) and no longer can penetrate cells. To penetrate the cells, the virus’ external protruding protein is recognized by surface proteins of cells called receptors, like a lock and key mechanism. So, if the protein structure is disrupted, it cannot fit into the receptors of the cells, therefore is not infectious. Another example is the egg white (ovalbumin), which is a viscous liquid normally, but when boiled, the protein changes it tertiary structure, denatures, and becomes the solid egg white we all recognize.


    Washing your hands for 20 seconds with soap and water will destroy the virus. The biochemistry of soap is a bifunctional molecule where ½ is organic loving (oils, grease) with its long chain of carbon atoms and is non-charged and the other ½ is charged (typically phosphate) and loves water. So, the soap latches onto the lipid bilayer of the virus and disrupts its integrity (the ordered “stacking” of the lipids internal to the membrane).  The charged part of the soap is surrounded by charged water molecules, which in turn pull the non-charged part of the soap, now inserted into the membrane, destroying the membrane by opening up the virus, thereby killing it, rendering in non-infectious. The diagram below shows that the lipid bilayer can no longer contain the RNA that renders the virus infectious.

    In this diagram, the soap is the blue molecule, with the long hydrocarbon tail inserted into the lipid bilayer of the COV-2 virus, disrupting the virus membrane resulting in loss of infectivity.


    To be effective in killing the COV-2 virus, the alcohol (either ethanol or isopropanol) has to be >70%. The mechanism that the alcohol kills the COV-2 virus or for that matter bacteria, is the electrostatic attraction of the positive charged group of the alcohol. The charged group is attracted to the negative portions of the proteins and denatures it by changing the conformation of the protein, (the 3-D structure). It is a mechanism by which protein biochemists can purify some proteins, through alcohol precipitation. The denatured protein on the virus, as cited above, cannot fit into the receptors of the target cells, thereby rendering in non-infectious. Sometimes, higher concentrations of mixtures of alcohol, (such as 80% ethanol + 5% isopropanol) are required to effectively inactivate lipid-enveloped viruses (such as HIVhepatitis B, and hepatitis C).


    There are many forms of Lysol, with varying chemical components that act as a biocidal agent. Most formulations contain the quaternary ammonium salt with a positive charge (benzalkonium chloride). These charged salts interrupt viral membranes, bind to proteins and act as bactericidal agents and antiviral agents to some viruses. Again, with the disrupted membrane, the COV-2 virus is rendered ineffective.


    This is the strongest biocidal agent for home use. It is an oxidizing agent that destroys the viral membrane and proteins, resulting in killing the COV-2 virus. Chlorine bleach (typically a >10% solution of sodium hypochlorite), is effective against most common pathogens, including disinfectant-resistant organisms such as tuberculosis (mycobacterium tuberculosis), hepatitis B and C, fungi, and antibiotic-resistant strains of staphylococcus and enterococcus. The benefits of chlorine bleach include its inexpensive and fast acting nature.



    According to the CDC, household (3 percent) hydrogen peroxide is effective in deactivating rhinovirus, the virus that causes the common cold, within 6 to 8 minutes of exposure. Rhinovirus is more difficult to destroy than coronaviruses, so hydrogen peroxide should be able to break down the coronavirus in less time. Spray the hydrogen peroxide on the surface to be cleaned, and let it sit on the surface for at least 1 minute. Hydrogen peroxide is not corrosive, so it’s okay to use it on metal surfaces.



    MarinBio scientists are experts in the molecular virology and biology of these and other infectious RNA agents, especially the nature and recognition of coronaviral receptors, viral RNA synthesis, and the molecular interactions governing viral pathogenesis and virion particle assembly and transmission. MarinBio scientists have over 25 years of experience helping our clients to develop, qualify and validate viral or cellular protein or RNA/DNA tests as well as a viral enzyme, anti-inflammatory drug potency assay or other quantitative bioassays. Our scientists have developed and manufactured a GMP 90 minute test used in multiple hospitals for acute sickle cell crisis patients. For further information please contact MarinBio at info@marinbio.com or call 415 883 8000 or visit our website at www.marinbio.com