Scientists working on the joint multi-site study have also found the virus strongly binds to a protein that protects cells from death
Scientists have found the virus which causes most deadly form of Sars is harmful to the central nervous system, according to a major study.
The scientists, working on the combined work, which included a joint WHO/MRC study, found that coronavirus causes the most severe form of the disease.
According to the study, the second most important form of coronavirus causes no greater damage, but people who catch the virus in hospitals tend to develop the disease much earlier and die more quickly.
The study is published in the journal Lancet Infectious Diseases. It shows how the Sars coronavirus, which has been found in all 28 countries of the world that have been affected to date, attacks fat tissue – the crucial components of tissue that make the nervous system work, such as blood vessels, bone marrow and soft tissue such as the hair follicles.
According to the researchers, the central nervous system is protected by a protein called NFkB that keeps it functioning normally by making it more permeable to surrounding blood vessels, as well as hindering membrane proteins that constantly hijack the system’s processes.
Publishing their findings, including those of the severe form of the disease, in the journal Lancet Infectious Diseases, scientists said a mutated form of coronavirus causes a disease that gradually destroys the structure of fat tissue, killing off important functions including fatty acid formation.
In the Sars coronavirus, the genes of the proteins protecting the nervous system were changed. This led to “a mismatch between the original protein and the new mismatch that was produced”, the scientists added.
The Sars virus first hit humans in October 2002 in the southern hemisphere, and spread throughout the world, killing 8,273 people.
Richard Pebody, professor of virology at the London School of Hygiene and Tropical Medicine, who led the team, said: “Resistance has been identified to many antiviral drugs, which increases the urgency of understanding if we can create an effective vaccine and, if so, which immune system aspects would be best targeted.
“Understanding fat tissue has key implications for developing new vaccines against the Sars coronavirus infection. The two forms of coronavirus differ considerably in how they attach to fat and are currently becoming even more different in their antispecific binding.
“Further studies could provide novel ways to prevent, diagnose, treat or protect against the development of the disease.”
Coronaviruses cause respiratory illnesses including the common cold, as well as Sars, and are endemic to several countries in the Middle East and south-east Asia. They are transmitted between humans through contact with contaminated surfaces or objects.
Dr Jeremy Farrar, director of the Wellcome Trust, which funded the study, said: “This is the first rigorous assessment of Sars coronavirus’s molecular changes since it emerged. The findings give us important insights into the earliest stages of infection, a critical time when viruses can more readily mutate.”
The study found how human cells lacking fat tissue tend to die within one day and that immunity declines quickly. The researchers said viruses only gain this ability during inflammation – which is most commonly linked to poor nutrition – so it is vital to know how fat tissue can help immune function.
Samples of the Sars coronavirus found in the tissue of patients were infected with different nucleotide sequences. But the researchers noted the virus and virus-like particles carrying it appear not to have evolved to spread around the brain with such great precision.
Andrew Wardley, the science advisor for science at the WHO, said: “This study provides clues to the molecular mechanisms of infection, which could help better diagnose and treat the disease, especially as only a limited number of laboratories in the world have the capacity to study these viruses.”
Despite the likelihood of it spreading, there have been no cases of Sars coronavirus, described as mild, outside the Arabian peninsula. However, the disease still causes billions of dollars in losses each year, particularly in the travel and tourism industries.
A further piece of the puzzle on how humans become infected was found in a separate international study published in Nature in April.