Although binding of pili to the complement regulatory protein, CD46, initiated infection in various cell types in vitro (Källström et al., 1997; Gill et al., 2003; Gill and Atkinson, 2004), and CD46 expression has been demonstrated in female genital tissue (Edwards et al., 2002), to date no pilus-CD46 interaction has been shown in vivo in male exudates (Edwards and Apicella, 2005). This evidence concerns the gene CD46 and infection.