Chemokines and viruses: friends or foes?

The chemokine-mediated movement of leukocytes from peripheral blood into tissues is essential for immunity in higher organisms. In addition, chemokines play crucial roles in controlling the development and functional aspects of leukocytes, and it is now apparent that their role is not only restricted to cell attraction. Recent in vitro and in vivo findings support the contribution of the chemokine system in the resolution of viral infections. However, the chemokine response to other viral infections can be detrimental to the host because of aberrant cellular activity. This review aims to provide insights into both sides of the chemokine spectrum, and will touch on aspects of chemokine mimicry by RNA viruses and the possible implication for disease outcome.