HIV-1 protecting CCR5-Delta32 allele in medieval Poland.

CCR5-Delta32 is the mutation in the chemokine receptor CCR5 that gives its homozygous carriers nearly complete protections from HIV-1 infection. Restricted almost exclusively to Europe, the mutation is thought to have originated in the continent and risen in frequency to the present-day value of approximately 10% due to a selective advantage it gave its carriers. The mutation bearing allele was initially calculated to be approximately 1000 years old and pandemic diseases, such as Bubonic Plague or smallpox were postulated to have selected it. However, new reports appear, that question these hypotheses. Data from ancient DNA (aDNA) studies prove the mutation to be much older, as suggested by calculations based on newer genetic maps. In order to investigate if the plagues of the last millennium selected the allele, and add to the discussion on CCR5-Delta32 origin and age, we searched for the mutation in aDNA isolated from individuals whose skeletal remains were collected at archaeological sites in Poland, dated back to 11-14th centuries. The calculated mean frequency of the allele in medieval Poland (5.06% as compared to contemporary 10.26%), implies its longer than previously believed presence in European populations, and suggests that historic pandemics had little effect on its present-day frequency.