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Optimal Immunity

An ERC-startup project
Pathogens evolve quickly and vertebrate hosts slowly – How can we keep up with all these pathogens? One important explanation is the enormous diversity that exists in the adaptive immune system of all vertebrates, including humans. The Major Histocompatibility Complex (MHC) is a key component in the adaptive immune system. The MHC genes are the most variable genes known in vertebrates and this variation is maintained by selection from pathogens, i.e. through host-pathogen interactions.

Collage with head shots of house sparrows and their wings.
House sparrows that have been caught in mist nets at one of the European sampling sites. Photo: Helena Westerdahl

I am particularly interested in the immune system of wild passerine birds and interestingly they have many more copies of MHC genes than mammals. In order to better understand the function of the immune system in passerine birds we are taking several different approaches in the project ‘Optimal-Immunity’. 

Genome project

We characterize the MHC region in several passerine species to know the gene order and to unravel gene rearrangements and gene duplication events that have occurred over evolutionary time.

Function of MHC genes

Genes of key importance during an immune response are highly expressed. We want to know which MHC gene copies that are expressed when, and to what degree, during an infection. 

A hand is holding a bird and its wing for measuring.
Measuring and sampling of a great reed warbler. Photo: Helena Westerdahl.

Host-pathogen interactions

A strong and wide selection from pathogens will select for different patterns in the immune genes than a weak and narrow selection. We study infection status and responses in immune genes over selection gradients in resident house sparrows Passer domesticus and migratory great reed warblers Acrocephalus arundinaceus and also during natural infections in captivity. We have a particular focus on avian malaria and how it varies in time and space. 

Antigen binding

MHC proteins bind and present antigens in different ways, some bind a wide range of antigens whereas other are strict. We want to figure out details of how passerine MHC proteins bind antigens by looking at their crystal structures.

Release of a captured great reed warbler.
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A the bow of a canoe is seen against blue water with reed in the background and blue sky.
Lake Kvismaren in south central Sweden, a breeding locality for great reed warblers. Photo: Helena Westerdahl.

People involved


European Research Council ERC

A woman is taking down nets among reeds.
Maja Tarka is folding the mist net after catching a great reed warbler male. Photo: Helena Westerdahl.