To investigate further the role of S. aureus proteases during influenza coinfection, we repeated the protocol employed by Tashiro et al. and fractionated culture supernatants of S. aureus strains Wood 46 (Fig. 1A), USA300 LAC and a deletion mutant of USA300 LAC deficient in the production of all known secreted proteases (20) (see Fig. S1A and B in the supplemental material) by size exclusion chromatography (SEC). This evidence concerns the gene LCT and influenza.