The MHC (Major Histocompatibility Complex) molecules play a crucial role in our immune system and MHC genes are the most variable genes known in vertebrates. This high variation is believed to be maintained by selection from a wide range of parasites and pathogens. The pathogen composition is changing both in time and space and hence has the potential to maintain a lot of diversity in the MHC genes.
We study several different natural parasite-host systems and try to understand how MHC varieties are selected for and against in natural populations depending on present and past selection from parasites/pathogens. We work with both MHC class I and II. MHC class I is primarily important for intra cellular pathogens, like viruses, and MHC class II for extra cellular pathogens, like many bacteria. We use several avian malaria-songbird systems and a Borreliarodent system to investigate how parasite-mediated selection acts on MHC.