Characterisation of a chikungunya virus from a German patient returning from Mauritius and development of a serological test

We have isolated a Chikungunya (Chik) virus from a patient who returned to Germany after a three-month visit to Mauritius in spring 2006. Upon return she developed a transient fever up to 40 degrees C. This was followed by myalgia and joint pain. IgG antibodies in serum to Chik virus were undetectable. Virus (Chik-Wu1) was isolated on Vero cells. We molecularly cloned the whole genome of Chik-Wu1 from viral RNA by RT-PCR. The complete sequence was determined and functional domains of the genome were assigned. Chik-Wu1 clearly belongs to the group of viruses analysed from the recent Indian Ocean outbreak. In order to develop tools useful for further characterization of Chik-Wu1 we bacterially expressed and purified the capsid (C) and envelope (E) proteins and established an immunoblot assay. Twenty-two of 30 serum samples from Chik virus-infected patients that scored positive in indirect immunofluorescence previously were also reactive in immunoblot analysis with recombinant C and E2 antigens.