July 14, 2004
HIV Resistance Mutation in the Bronze Age
Detection of the Δ32ccr5 HIV resistance gene in Bronze Age skeletons
Susanne Hummel et al.
Introduction
A mutant allele (Δ32ccr5) of the chemokine receptor CCR5 which confers resistance to HIV infection is believed to have originated from a single mutation event in historic times and expanded rapidly in Caucasian populations caused by an unknown selective advantage. In particular the Yersinia pestis bacillus is discussed as a source of strong selective pressure on European populations in medieval times. Due to the specific allele frequency gradient in Europe and STR linkage analysis the first occurrence of the mutation is dated back to approx. 700-3000 yrs ago in North Eastern Europe (Libert et al.1998, Stephens et al.1998). Our study reports amplifications of the mutant allele from four different burial sites in Germany and one in Southern Italy dating back as far as 3000 years indicating the first mutation to have happened much earlier as calculated from the modern population studies.
Material and Methods
The frequencies of the Δ32ccr5 allele were determined for 19 individuals of an Early modern times burial site in Central Germany, 19 individuals of an Early modern times burial site in Southern Italy, 14 individuals of a plague mass grave (14th century) from Northern Germany, 20 individuals of a famine mass grave (14th century) from Northern Germany, and 17 individuals of a Bronze Age burial site (900 B.C.) from Central Germany. The amplifications of the bi-allelic immunogenetic marker were carried out in multiplex PCRs which amplifies autosomal STR markers for individual specific typing simultaneously in order to ensure the authenticity of the results.
Results and Conclusions
In contrast to the current hypothesis our findings indicate that the mutation was already present in a considerable frequency (4 out of 17 individuals revealed the mutant allele) among prehistoric Europeans dating back to approx. 3000 years. Also, there is no statistically provable difference in the allele frequencies for the pre- and post plague mass graves from Lübeck (14th cent., Northern Germany) arguing against Y. pestis to have represented a strong selective force in the spread of the Δ32ccr5 mutation. Further, by comparing the findings from the German and Italian burial site from early modern times a considerable North south gradient, as revealed by modern population studies is seen.
HIV resistance is actually most common today in eastern Poland, the Baltic states and western Finland.
Posted by: Polak at July 15, 2004 07:35 PMPerhaps this mutation is how a population of (semi) hunter-gatherers adapted to diseases which formerly prevented them from living in permanent villages, such as salmonella or hepatitis. The timing could be similar to the spread of agriculture on to the coastline in the high-incidence districts. Maybe permanent seafront villages, appearing around that time, that far north, allowed for more sea-borne commerce in these regions, if the inhabitants who had the mutation were spared from disease, which otherwise would wipe out the bases of such commerce, or of a newly advanced fishing.
Posted by: John S Bolton at July 25, 2004 08:24 PM