Pathogens maketh man 7 January 2004 9:00 GMT by Jane Bradbury
The infectious activity of pathogens over the centuries has left an indelible mark on the human
genome, report evolutionary biologists. Now, protection that evolved against pathogens that blighted
human populations hundreds of years ago appears to have evolved into protection against more recent
arrivals, such as HIV.
Researchers at Duke University in Durham, North Carolina have found that infection throughout
history may have driven the selection of a single nucleotide polymorphism in the promoter of the
gene encoding the cytokine interleukin 4 (IL-4).
Gene variants like this that regulate the expression of genes particularly interest Duke
evolutionary biologist Matthew Rockman. Many of them are present at varying frequencies in different
human populations, he explains. "As evolutionary biologists, we want to understand how these
different frequencies arise."
High IL-4 expression, which shifts T-cells towards the so-called Th2 phenotype and induces B cells
to secrete IgE, is associated with allergies and some respiratory infections. Nevertheless, the -
524T allele of IL-4, which increases IL-4 expression threefold compared with the -524C allele, is
common in some human populations.
Read the rest at BioMedNet gateways.bmn.comstoryOpen ↗
Posted by Robert Karl Stonjek.