Medieval Plague May Explain Resistance to HIV

LONDON (Agence de Presse Medicale) - The persistent epidemics of hemorrhagic fever that struck Europe during the Middle Ages provided the selection pressures that have made 10 percent of Europeans resistant to HIV infection, according to a UK study.

A mutation called delta-32 in the cellular receptor dubbed CCR5 protects against HIV infection, and is found more often in Europeans than other populations.

Scientists have previously suggested that the genetic mutation became common because it protected people against the Black Death or smallpox epidemics, while those with normal CCR5 were wiped out.

But researchers at the University of Liverpool in England said computer modeling, based on the changing demographics of Europe from 1000 to 1800 AD, showed how hemorrhagic fever forced up the frequency of this mutation from 1 in 20,000 at the time of the Black Death to values today of 1 in 10.

The researchers note in the Journal of Medical Genetics that lethal, viral hemorrhagic fevers were recorded in the Nile valley from 1500 BC and were followed by the plagues of Mesopotamia (700-450 BC), the plague of Athens (430 BC), the plague of Justinian (AD 541-700) and the plagues of the early Islamic empire (AD 627-744).

The European plagues from 1347 to 1665 were also a continuing series of hemorrhagic infections caused by a virus that used the CCR5 as an entry port into the immune system, the researchers explain.

Although plague passed its peak after the Great Plague of London in 1665, the researchers said it did not disappear completely.

Professor Christopher Duncan, from the University's School of Biological Sciences, added: "Hemorrhagic 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 hemorrhagic plague provided continuing selection pressure on the mutation and explains why it (the CCR5-delta-32 mutation) occurs today at its highest frequency in Scandinavia and Russia."

I have avoided using the word 'frequency' in my comments on this thread. I also think that it might be a case of the immune systems generally being weakened in those who succombed to the plague, and this is not necessarily genetics at play. There also are those with stronger immune systems who survived the plague, perhaps being exposed to the virus without becoming ill. We know this happens with many diseases today, and it is not necessarily conditional on 'vaccination'. Is this genetics?

If it is genetics, I might suggest that a strong immune system was the 'original' condition in humans, and that the weakened immune system is the 'mutation'.

Today our immune systems are weakened by many factors. Vaccines tend to have an adverse effect to the overall health of the immune system. Antibiotics are now working against us by creating resistant strains of bacteria and viruses. Our overall health is also a factor. This can relate to such basic things as dietary habits and environment.

There are also naturally occurring substances that can be used to strengthen our overall immune quotient. I believe that we can do some things to consciously strength our immune systems, even to the point of dealing with these 'new' or 'more potent' microbes that may be on the attack.

I also believe that in some cases our immune systems can be 'educated' to attack and eliminate serious diseases that are already at work in our bodies - such things as cardiovascular disease and other disorders of imflamatory origin, even cancer. However, when we do this by 'educating' our immune system, we are not changing our genetics.

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