More recently it has also been suggested that the 19 kDa protein acts an adhesin [21]. Many of the above studies of the

19 kDa were performed with purified or recombinant protein that may not fully reflect the role of the molecule in the context Go6983 of natural infection. In particular expression in E. coli is unlikely to reproduce native patterns of post-translational modiufication. We have previously reported the effect of deletion and overexpression of the 19 kDa on the innate immune response [22]. We found that the deletion mutant (Δ19) was moderately impaired in its ability to multiply in human monocyte-derived macrophages (MDM). Surface expression of MHC class II molecules was reduced in phagocytes infected with

MTB; this effect was not seen in cells infected with Δ19. Δ19 induced lower IL-1β secretion from monocytes and MDM. Overexpression of the 19 kDa increased IL-1β, IL-12p40 and TNF-α secretion irrespective of phagocyte maturity. These findings confirmed the 19 kDa protein to be an important mediator of the innate immune response in the context of the whole bacillus. In addition to being acylated, the 19 kDa protein is glycosylated [23, 24]. Earlier work in our laboratories established that poly threonine motifs towards the N-terminal of the molecule selleck chemicals llc form a

major glycosylation site [23, 24]. The aim of this study was therefore to evaluate the innate immune response to Δ19 mutants that had been complemented with a single copy of mutagenised 19 kDa molecules lacking the motifs for acylation and O-glycosylation respectively. Methods Generation of recombinant strains of M. tuberculosis The 19 kDa gene was deleted from M. tuberculosis (MTB) H37Rv to produce the Δ19 strain as previously described [22]. Complementation of the Δ19 strain by the native and modified (non-acylated NA, and non-O-glycosylated Adenosine triphosphate NOG) 19 kDa genes led to the strains Δ19::19, Δ19::19NA and Δ19::19NOG. For complementation, the native sequence (including the entire intergenic region and part of upstream Rv3762 ORF) was amplified by PCR from H37Rv DNA. The site-directed mutagenised genes were amplified from previous episomal constructs [24, 25] engineered to come under the control of the endogenous 19 kDa promoter. Complementation was performed using the integrating vector pKINTA, based on the L5 phage integration system [26], which reintroduces a single copy of the 19 kDa gene into the chromsome under the control of its own promoter at the attB site [27].