OmpH cross-reacted with one of the Legionella pneumonia or streptococcal pneumonia patient sera; GroEL cross-reacted with one of the Legionella pneumonia and two of the rickettsial spotted fever patient sera; RplL cross-reacted with two of the Legionella pneumonia and three of the streptococcal pneumonia patient sera (Table 3). This evidence concerns the gene HSPD1 and Legionnaires' disease.