Interestingly, hBD-3 liberation was not reduced in infections with type II or IVB secretion system mutant strains, suggesting that recognition of bacterial membrane component via TLR2, recognition of Legionella-flagellin via TLR5 and/or non-methylated bacterial DNA through TLR9 might be the major pathways for L. pneumophila induced hBD-3. This evidence concerns the gene TLR9 and infection.