Researchers have found a further reason for the severity of dual infection by influenza and Streptococcus pneumonia -- a new virulence mechanism for a surface protein on the pneumonia-causing bacteria S. pneumoniae. This insight comes 30 years after discovery of that surface protein, called pneumococcal surface protein A. This mechanism had been missed in the past because it facilitates bacterial adherence only to dying lung epithelial cells, not to living cells.