Andersen Lab

We are using infectious disease genomics to investigate the interaction between the human host and highly pathogenic viruses such as Zika, Ebola, and Lassa. Our goal is to understand how these viruses evolve in response to selection pressures imposed by the host immune system. Using a combination of computational biology, experimentation, and field work in West Africa our hope is to change the way we develop vaccines and therapeutics for these and other emerging pathogens.


Positions available

Come join us at the beautiful Scripps Research Institute campus in La Jolla, California. We are currently looking to hire wet lab and computational postdocs.


Origin and intrahost evolution of Lassa virus

Cover of CellThe ongoing epidemic of Ebola virus disease in West Africa reminds us how little is known about biosafety level-4 viruses. Like Ebola virus (EBOV), Lassa virus (LASV) can cause hemorrhagic fever with case fatality rates in excess of 50%. Unlike EBOV, however, LASV is endemic in Nigeria, Sierra Leone, Guinea, and Liberia, leading to severe disease in tens of thousands of people each year.

In a recently released study in the journal Cell, we generated a genomic catalog of almost 200 LASV sequences collected from clinical and rodent reservoir samples. Based on this dataset, we obtained unique insights into the origins and evolutionary dynamics of this devastating virus. We show that while Ebola epidemics are usually sustained by human-to-human transmissions, LASV infections mainly result from reservoir-to-human infections. In other words, whereas most Ebola patients get infected from other Ebola patients, Lassa patients are mostly the result of independent spill-over events from the rodent reservoir.

We also used this data to elucidate the likely spread of LASV across West Africa and show that this migration was accompanied by changes in LASV genome abundance, fatality rates, codon adaptation, and translational efficiency. By investigating intrahost evolution, we found that mutations accumulate in epitopes of viral surface proteins, suggesting selection for immune escape. It is our hope that this genomic catalog will serve as a foundation for the development of vaccines and diagnostics.

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Zika virus pilot

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We recently received plasma samples from Zika virus (ZIKV) patients in Colombia. We performed QC on the samples and unfortunately very few had detectable levels of ZIKV by qPCR. We extracted RNA from two of these patient samples (Z184 and Z186), as well as a positive control (seed stock of the Malaysian strain P6-740 passaged once on BHK-21 cells) kindly provided by Nathan Grubaugh and Greg Ebel at Colorado State.

Feature in Politiken

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The leading Danish newspaper Politiken had a feature on our work in the September 20th 2015 Sunday section. The article discusses our past and ongoing work with Lassa and Ebola. The full feature describes how we have investigated both Lassa and Ebola virus evolution based on our most recent papers in Cell and Science.

Lassa paper on the front page of Cell

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In a large multi-disciplinary collaboration between partners in Sierra Leone, Nigeria, USA, and Europe, we have published our first study on Lassa virus evolution. The paper – which appears on the front page of the August issue of Cell – is the result of seven years of work on Lassa fever across West Africa.