Fig. 3.

Experimental evolution in tick cells. A Tick cells offer a versatile system in which selected pathogens could be cultured under single and different modes of co-infections (i.e. simultaneous or sequential). The same tick cell line can be infected with several pathogens which can be continuously subcultured to assess short-term (e.g. 3–5 passages) and/or long-term evolution (e.g. 10–15 passages). B Pathogen fitness under single infections and co-infections can be measured by real time PCR and compared between groups and modes of evolution or coevolution (i.e. fluctuating selection and arms race) can be assessed (C). D Comparative systems biology approaches such as genomics, transcriptomics, and proteomics can be used following bouts of evolution to measure genetic and phenotypic changes of pathogens during co-infections. The same approaches (e.g. transcriptomics and proteomics) can be used to test the response of tick cell to multi-pathogen infection.