Cover photograph (Copyright © 2008, American Society for Microbiology. All Rights Reserved.): Group A Streptococcus interaction with a human polymorphonuclear leukocyte. The scanning electron microscopic image shows a strain of serotype M1 group A Streptococcus (maize) interacting with the surface of a human polymorphonuclear leukocyte (blue). Group A Streptococcus produces an extracellular protease that cleaves granulocyte chemotactic protein 2 (GCP-2) and growth-related oncogene alpha (GROα), two potent chemokines made abundantly in human tonsils. Cleavage of GCP-2 and GROα by the Streptococcus pyogenes cell envelope protease abrogates their ability to prime leukocytes for activation, detrimentally altering the innate immune response. (Image courtesy of David R. Dorward and Anita Mora, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana.) (Related paper is on p. 978.)