HIV infection and the European Defense
A group of biologists at the University of Liverpool may have discovered the reason why as many as 10% of Europeans exhibit a natural resistance to HIV.
The human immunodeficiency virus (HIV) pandemic has caused over 25 million deaths since its formal discovery in 1981. HIV leads to acquired immunodeficiency syndrome (AIDS), whereby one’s helper T cells diminish to the point of considerable vulnerability to opportunistic infection. AIDS-related death — for several reasons — has been disproportionately high in Africa, though its effect is undeniable worldwide and made notorious by its transmission vectors of choice, including needle sharing, unprotected sex, blood transfusion, and perinatal infection.
Once diagnosed, antiviral therapy can be effective in reducing and delaying the severity of AIDS-related symptoms, though this varies from person to person. Similarly, the genetic resistance described by this study only lends its protection to a fraction of the (mostly European) population.
CCR5-delta 32 is a genetic mutation that runs interception against oncoming HIV presence, preventing the virus from squatting inside targeted helper T cells. This mutation has been identified in the past, but its very presence has been puzzling. Why would this mutation be so much higher in Scandanavian areas yet so much lower outside of the Mediterranean?
Remember, too, that HIV was formally diagnosed in 1981 — far too recent for a complex mutation to selectively spread through an area based on this virus alone.
Duncan and Scott suggest that this mutation actually formed out of response to severe illnesses of the past — including, chiefly, smallpox. “The plagues were confined to Europe, persisted for more than 300 years and had a 100% case mortality,” Duncan explains.
In 2004, the authors investigated the nature of and mechanisms by which the historic plagues of Europe wrought such considerable destruction. The various epidemics of years past — most a variant of viral, hemorrhagic (and always lethal) fever — used CCR5, the non-mutated counterpart, as a method of infection. Given the lethality of these plagues (along with sophisticated computer modeling), it makes sense that this mutation grew from 1 in 20,000 people (historically) to closer to 1 in 10 today.
It’s less clear whether this possible viral history — or the nature of the genetic mutation itself — will lend itself particularly well to future preventative medications, but in the case of lethal viral infections, knowing is half the battle.
University Of Liverpool (2005, April 3). Biologists Discover Why 10 Percent Of Europeans Are Safe From HIV Infection. ScienceDaily. Retrieved May 24, 2011, from http://www.sciencedaily.com/releases/2005/03/050325234239.htm
Global HIV Prevalence map (2001). World Health Organization. Retrieved May 24, 2011, from http://gamapserver.who.int/mapLibrary/app/searchResults.aspx
HIV virus spreading from infected CD4 cell (cover image). Retrieved May 24, 2011, from http://hiv.boehringer-ingelheim.com/com/HIV/Information_material/Images3.jsp