Could Covid-19 trigger multiple sclerosis?

A new study has found a protein in SARS-CoV-2, the virus that causes Covid-19, is structurally similar to proteins that the immune system attacks in multiple sclerosis (MS).

The researchers said this could show a potential mechanism for how Covid-19 could trigger a disease such as MS in susceptible people.

The contribution of Covid-19 to other human diseases is still relatively unknown, but there have been anecdotal reports of people going on to develop neurological conditions, including MS, not long after having Covid-19.

There isn’t data to suggest the virus can trigger MS, but there is a growing body of research that suggests other viruses can – most notably the Epstein-Barr virus (EBV).

Immune cells in the human body have specialised receptors that bind to specific targets – viruses and bacteria that pose a threat to us. In autoimmune diseases such as MS, immune cells bind to the body’s own healthy tissues, attacking them. In MS, they attack the fatty covering of the nerve fibres – the myelin sheath.

Researchers in this study hypothesised that proteins in SARS-Cov-2 may be similar in structure to proteins in the brain and that immune cells fighting the virus may also bind to brain proteins and cause an autoimmune response. This process is called molecular mimicry and a similar process has been established to exist for EBV and MS.

The scientists analysed more than 100 brain proteins established as immune cell targets in MS along with the structure of the virus’s proteins. While many of the proteins didn’t show structural similarities to any MS proteins, the virus’s nucleocapsid protein had structural similarities to 22 MS-related proteins. An analysis of an MS-related protein, myelin proteolipid protein, showed the similarities found were in the regions that activate immune cells.

The researchers said these results suggested a variety of proteins might be involved in triggering the autoimmune response associated with MS disease development in some people.

“Overall, these results provide a computational basis for the potential of SARS-CoV-2 to initiate T-cell-driven molecular mimicry through specific MS-associated proteins,” they said, noting that further research would allow better understanding on how Covid-19 interacts with the immune system.