Molecular bases of interactions between hosts and pathogenic microorganisms

Despite of advances in prevention, diagnosis and treatment of infectious diseases, pathogenic micro organisms remain the most important threat to humans and animals. Recent investigations provided some general data that enable better understanding of host pathogen interactions. A key role in the recognition of pathogen (and its antigens like LPS, lipoproteins, RNA, DNA etc.) play so-called TLR (Toll-Like Receptors) which are present on the surface of cells like macrophages, dendritic cells (DC) and on other cells. TLR (TLR1-TLR9) enable activation of the innate immunity effectors, as well as signals that activate an adaptive immunity. Actually, there are many other proteins which enable the transfer of the signal from TLR to the nuclear factor kappa B (NF-kB), which is responsible for induction of expression of several genes being involved in inflammatory and immune response.In chicken a lower number of TLR (TLR1, TLR2, TLR3) than mammals has been found. In addition, recent search of chicken EST sequences identified genes for proteins with known involvement in the TLR pathway (IRAK4, MAL, MyD88, TRAF6), but did not find homologues of some TLRs, or IRAK1, IRAK2 and IRAK9 as well as other proteins of TLR signalling pathway. So, those novel data enable more targeted investigations of interactions between chicken cells (or tissues) and the selected pathogen.It seems that, generally, chicken TLR2 can recognize lipoproteins which are major but variably expressed antigens in several Mycoplasma spp. It is known that hemagglutinins of MG and MS are lipoproteins but their interactions with chicken cells e.g. macrophages, DC, lymphocytes (B and T) and other cells are not known. Using modern tools of functional genomics (microarrays, RT-PCR, mAbs) we will investigate host pathogen interactions in the chicken model during the MG and MS infection.