BREAKING! Spanish Study Shows That SARS-CoV-2 Spike Glycoproteins Can Interact With Oily Human Skin, Sebum And Skin Ceramides!
Alarming study findings have emerged from a new study conducted by Spanish researchers from the Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC)-Spain in which it was found that the SARS-CoV-2 coronavirus spike glycoproteins were able to interact with oily human skin surfaces and also skin sebum and ceramides.
The study team said in their abstract that the possibility of contamination of human skin by infectious virions plays an important role in indirect transmission of respiratory viruses but little is known about the fundamental physico-chemical aspects of the virus-skin interactions.
When it comes to coronaviruses, the interaction with surfaces (including the skin surface) is mediated by their large glycoprotein spikes that protrude from (and cover) the viral envelope.
The study team performed various atomic simulations between the SARS-CoV-2 spike glycoprotein and human skin
The used a model of an “oily” skin covered by sebum and a “clean” skin exposing the stratum corneum.
The laboratory simulations show that the spike tries to maximize the contacts with stratum corneum lipids, particularly ceramides, with substantial hydrogen bonding. In the case of “oily” skin, the spike is able to retain its structure, orientation and hydration over sebum with even interaction with sebum components.
Comparison of these study findings with previous simulations of the interaction of SARS-CoV-2 spike with hydrophilic and hydrophobic solid surfaces, suggests that the ”soft” or “hard” nature of the surface plays an essential role in the interaction of the spike protein with materials.
The study findings were published on a preprint server and are currently being peer reviewed. https://www.biorxiv.org/content/10.1101/2021.07.13.452154v1
The SARS-CoV-2 coronavirus, which was first detected in December 2019 in Wuhan, China, is the causal agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic. It is the third documented case this century of an animal coronavirus spilling over to humans and resulting in a major outbreak.
The alarming potential for the contamination of human skin by SARS-CoV-2 virions can play a key role in the transmission of respiratory viruses, but little is known about the physico-chemical processes governing virus-skin interactions.
Typically the transmission of respiratory viruses like SARS-CoV-2 typically involves the release of virus-containing aerosols and droplets from infected individuals when they cough, sneeze, breathe or speak. These may then infect others via direct mechanisms (e.g., inhalation of aerosols) or indirect mechanisms (e.g., contact with the virus-containing droplets deposited onto materials). Reaerosolization after deposition, such as shaking a contaminated blanket, is another means of indirect transmission.
However the indirect transmission mechanism has been documented in several studies, and human skin-virus interactions play a key role in this mechanism. Some key factors to be considered are the adhesion strength of the virion to human skin, the virion’s hydration upon adhesion,
and whether it retains its integrity or not post-adhesion.
At present, there is a lack of understanding of the physico-chemical features of the interaction between coronaviruses and different surfaces.
This news study documents the molecular details of the interaction between the human skin and SARS-CoV-2.
The novel coronavirus interacts with the environment with the help of its spike protein (S) that protrudes from its envelope.
The study team considered atomistic molecular dynamics simulations of the interactions between S and the human skin. Human skin is, of course, a complex surface and, hence, the scientists considered two cases: (i) clean skin without hair and sebaceous glands and (ii) skin covered by an oily waxy layer (sebum).
The exposed surface of the skin corresponds to the outermost layer of the epidermis, which is also known as the stratum corneum (SC).
The study team studied the interaction of S with “oily skin” and “clean skin” surfaces.
The researchers note that the surfaces of both types of skin have different molecular organizations (e.g., the ability to build hydrogen bonds). They also considered simulations of wet skin by placing a drop of water on each surface.
The study team performed four sets of simulations ie wetting simulations of the two skin models and their interaction with the SARS-CoV-2 spike protein.
Also, as a reference, a simulation of the interaction of S with a phosphatidylcholine (POPC) was also performed. To reproduce physiological skin temperature, the temperature was set at 305K, and the CHARMM36 force field was used, which includes parameterization of proteins, lipids, and general organic molecules.
The study simulation results show striking differences between the two skin types. In the case of clean skin, S adsorbs, keeping its long axis almost parallel to the lipid surface. This aids in maximizing the contact between the spike and the surface of the stratum corneum. In the case of oily skin, the spike protein retains its perpendicular orientation with the host’s receptor-binding domain (RBD).
Interestingly the case of hydration of the spike protein is also different in the two cases.
In the case of clean skin, the study team observed a complete wetting of the stratum corneum bilayer. This could compete with the tendency of the spike protein to remain hydrated, which could, in turn, influence the orientation of S over the stratum corneum. In the case of oily skin, the spike protein was maintained inside a hydration droplet that was formed on the top of the sebum layer.
The study findings demonstrate that there is a much smaller contact angle for a water droplet on stratum corneum when compared to sebum.
The study team observed a strong interaction of S with ceramides in SC and triglycerides in sebum. The number of hydrogen bonds between S and the skin molecules is also much higher in the former case.
The study findings conclude that the interactions with sebum will maintain the integrity of the hydrated SARS-CoV-2 spike. In the case of clean skin, a disruption of the virus’s integrity is possible.
The research team did however highlight some study limitations for instance in the study, the scientists considered only the S1 subunit of the spike glycoprotein and not the entire virus envelope. This may impact the potential change in orientation of the S protein and lead to a possible rupture between S1 and S2 subunits. A second limitation is the omission of some skin aspects from the model, such as rugosity, porosity, etc.
A more detailed research that addresses these limitations is currently underway by the same team.
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