Adherence of B. henselae Marseille (B.h. M), B. quintana Toulouse (B.q. T), B. quintana Munich (B.q. M), B. quintana JK-31 (Vomp+) (B.q. JK-31), and B. quintana 2-D70 (Vomp−) (B.q. 2-D70) to THP-1 macrophages (A) and HeLa 229 cells (B). THP-1 cells were differentiated by treatment with PMA. Cells were infected at an MOI of 100, and adherence was determined 30 min after infection. An asterisk indicates that a value is significantly different from the value obtained for B. henselae Marseille (P < 0.05).