Biologists discover why 10percent of Europeans are safe from HIV infection

March 10, 2005

Biologists at the University of Liverpool have discovered how the plagues of the Middle Ages have made around 10% of Europeans resistant to HIV.

Scientists have known for some time that these individuals carry a genetic mutation (known as CCR5-delta 32) that prevents the virus from entering the cells of the immune system but have been unable to account for the high levels of the gene in Scandinavia and relatively low levels in areas bordering the Mediterranean.

They have also been puzzled by the fact that HIV emerged only recently and could not have played a role in raising the frequency of the mutation to the high levels found in some Europeans today.

Professor Christopher Duncan and Dr Susan Scott from the University’s School of Biological Sciences, whose research is published in the March edition of Journal of Medical Genetics, attribute the frequency of the CCR5-delta 32 mutation to its protection from another deadly viral disease, acting over a sustained period in bygone historic times.

Some scientists have suggested this disease could have been smallpox or even bubonic plague but bubonic plague is a bacterial disease rather than a virus and is not blocked by the CCR5-delta 32 mutation.

Professor Duncan commented: “The fact that the CCR5-delta 32 mutation is restricted to Europe suggests that the plagues of the Middle Ages played a big part in raising the frequency of the mutation. These plagues were also confined to Europe, persisted for more than 300 years and had a 100% case mortality.”

Around 1900, historians spread the idea that the plagues of Europe were not a directly infectious disease but were outbreaks of bubonic plague, overturning an accepted belief that had stood for 550 years. Professor Duncan and Dr Scott illustrated in their book, Return of the Black Death (2004, Wiley), that this idea was incorrect and the plagues of Europe (1347-1660) were in fact a continuing series of epidemics of a lethal, viral, haemorrhagic fever that used the CCR5 as an entry port into the immune system.

Using computer modeling, they demonstrated how this disease provided the selection pressure that forced up the frequency of the mutation from 1 in 20,000 at the time of the Black Death to values today of 1 in 10.

Lethal, viral haemorrhagic fevers were recorded in the Nile valley from 1500 BC and were followed by the plagues of Mesopotamia (700-450BC), the plague of Athens (430BC), the plague of Justinian (AD541-700) and the plagues of the early Islamic empire (AD627-744). These continuing epidemics slowly raised the frequency from the original single mutation to about 1 in 20,000 in the 14th century simply by conferring protection from an otherwise certain death.

Professor Duncan added: “Haemorrhagic plague did not disappear after the Great Plague of London in 1665-66 but continued in Sweden, Copenhagen, Russia, Poland and Hungary until 1800. This maintenance of haemorrhagic plague provided continuing selection pressure on the CCR5-delta 32 mutation and explains why it occurs today at its highest frequency in Scandinavia and Russia.”

Source: University of Liverpool

Explore further: Clinical gene discovery program solves 30 medical mysteries

Related Stories

Clinical gene discovery program solves 30 medical mysteries

September 17, 2018
A table in a recently published paper tells the story of 30 families who have, sometimes after years of searching, finally received an answer about the condition that has plagued one or more family members. The Brigham Genomic ...

Discovering the ancient origin of cystic fibrosis, the most common genetic disease in Caucasians

September 7, 2018
Imagine the thrill of discovery when more than 10 years of research on the origin of a common genetic disease, cystic fibrosis (CF), results in tracing it to a group of distinct but mysterious Europeans who lived about 5,000 ...

What is the plague?

July 29, 2014
Cases of plague have been reported in the Chinese city of Yumen, where a man has died of the disease.

Plague in humans 'twice as old' but didn't begin as flea-borne, ancient DNA reveals

October 22, 2015
New research using ancient DNA has revealed that plague has been endemic in human populations for more than twice as long as previously thought, and that the ancestral plague would have been predominantly spread by human-to-human ...

Are amoebae safe harbors for plague?

January 16, 2018
Amoebae, single-celled organisms common in soil, water and grade-school science classrooms, may play a key role in the survival and spread of deadly plague bacteria.

Did the second plague pandemic reach Sub-Saharan Africa?

October 11, 2017
He has not found irrefutable evidence yet but is confident that it exists. For now, Gérard Chouin continues to amass what circumstantial evidence he can for his hypothesis.

Recommended for you

Researchers identify a new cause of childhood mitochondrial disease

September 20, 2018
A rapid genetic test developed by Newcastle researchers has identified the first patients with inherited mutations in a new disease gene.

Test could detect patients at risk from lethal fungal spores

September 20, 2018
Scientists at The University of Manchester have discovered a genetic mutation in humans linked to a 17-fold increase in the amount of dangerous fungal spores in the lungs.

Why some human genes are more popular with researchers than others

September 18, 2018
Historical bias is a key reason why biomedical researchers continue to study the same 10 percent of all human genes while ignoring many genes known to play roles in disease, according to a study publishing September 18 in ...

Class of neurological disorders share 3-D genome folding pattern, study finds

September 18, 2018
In a class of roughly 30 neurological disorders that includes ALS, Huntington's Disease and Fragile X Syndrome, the relevant mutant gene features sections of repeating base pair sequences known as short tandem repeats, or ...

Researchers resolve decades-old mystery about the most commonly mutated gene in cancer

September 18, 2018
The most commonly mutated gene in cancer has tantalized scientists for decades about the message of its mutations. Although mutations can occur at more than 1,100 sites within the TP53 gene, they arise with greatest frequency ...

Study of one million people leads to world's biggest advance in blood pressure genetics

September 17, 2018
Over 500 new gene regions that influence people's blood pressure have been discovered in the largest global genetic study of blood pressure to date, led by Queen Mary University of London and Imperial College London.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.