Science Daily, 2015/11/10 – New research from the University of Southampton has found that copper can effectively help to prevent the spread of respiratory viruses, which are linked to severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
Animal coronaviruses that ‘host jump’ to humans, such as SARS and MERS, result in severe infections with high mortality. The Southampton researchers found that a closely-related human coronavirus — 229E — can remain infectious on common surface materials for several days, but is rapidly destroyed on copper.
A newly-published paper in mBio — a journal of the American Society for Microbiology — reports that human coronavirus 229E, which produces a range of respiratory symptoms from the common cold to more lethal outcomes such as pneumonia, can survive on surface materials including ceramic tiles, glass, rubber and stainless steel for at least five days. While human-to-human transmission is important, infections can be contracted by touching surfaces contaminated by respiratory droplets from infected individuals, or hand touching, leading to a wider and more rapid spread
On copper, and a range of copper alloys — collectively termed ‘antimicrobial copper’ — the coronavirus was rapidly inactivated (within a few minutes, for simulated fingertip contamination). Exposure to copper destroyed the virus completely and irreversibly, leading the researchers to conclude that antimicrobial copper surfaces could be employed in communal areas and at any mass gatherings to help reduce the spread of respiratory viruses and protect public health.
Lead researcher Dr Sarah Warnes said: “Transmission of infectious diseases via contaminated surfaces is far more important than was originally thought, and this includes viruses that cause respiratory infections. This is especially important when the infectious dose is low and just a few virus particles can initiate an infection.
“Human coronavirus, which also has ancestral links with bat-like viruses responsible for SARS and MERS, was found to be permanently and rapidly deactivated upon contact with copper. What’s more, the viral genome and structure of the viral particles were destroyed, so nothing remained that could pass on an infection. With the lack of antiviral treatments, copper offers a measure that can help reduce the risk of these infections spreading.”
Speaking on the importance of the study, Professor Bill Keevil, co-author and Chair in Environmental Healthcare at the University of Southampton, said: “Respiratory viruses are responsible for more deaths, globally, than any other infectious agent. The evolution of new respiratory viruses, and the re-emergence of historic virulent strains, poses a significant threat to human health.
“The rapid inactivation and irreversible destruction of the virus observed on copper and copper alloy surfaces suggests that the incorporation of copper alloy surfaces — in conjunction with effective cleaning regimes and good clinical practice — could help control transmission of these viruses.”
Previous research by Professor Keevil and Dr Warnes has proved copper’s efficacy against norovirus, influenza and hospital superbugs, such as MRSA and Klebsiella, plus stopping the transfer of antibiotic resistance genes to other bacteria to create new superbugs.
The Science Behind Antimicrobial Copper
Cuverro – The mechanism by which antimicrobial copper kills bacteria is complex by nature, but the effect is simple. Science suggests that antimicrobial copper kills bacteria with a multifaceted attack. The questions and answers below summarize active and ongoing research seeking to explain the antimicrobial copper kill mechanism.
How does copper affect bacteria?
Science suggests that copper surfaces affect bacteria in two sequential steps: the first step is a direct interaction between the surface and the bacterial outer membrane, causing the membrane to rupture. The second is related to the holes in the outer membrane, through which the cell loses vital nutrients and water, causing a general weakening of the cell.
How can copper punch holes in a bacterium?
Every cell’s outer membrane, including that of a single cell organism like a bacterium, is characterized by a stable electrical micro-current. This is often called “transmembrane potential” and is, literally, a voltage difference between the inside and the outside of a cell. It is strongly suspected that when a bacterium comes in contact with a copper surface, a short circuiting of the current in the cell membrane can occur. This weakens the membrane and creates holes. Another way to make a hole in a membrane is by localized oxidation. This happens when a single copper molecule, or copper ion, is released from the copper surface and hits a building block of the cell membrane (either a protein or a fatty acid). If the “hit” occurs in the presence of oxygen, we speak of oxidative damage.
After punching holes, how do copper ions further damage the cell?
Now that the cells main defense (its outer membrane) has been breached, there is an unopposed stream of copper ions entering the cell. This puts several vital processes within the cell in danger. Copper literally overwhelms the inside of the cell and obstructs cell metabolism (i.e., the biochemical reactions needed for life). These reactions are accomplished and catalyzed by enzymes. When excess copper binds to these enzymes, their activity grinds to a halt.
The bacterium can no longer breathe, eat, digest, or create energy.
How can copper’s effect be so fast, and affect such a wide range of microorganisms?
Experts explain the speed with which bacteria perish on copper surfaces by the multi-targeted nature of copper’s effects. After membrane perforation, copper can inhibit enzymes and stop the cell from transporting or digesting nutrients, from repairing its damaged membrane, and from breathing or multiplying. It is also thought that this is why such a wide range of bacteria are susceptible to contact action by copper.