Mycoplasma gallisepticum is the primary etiological agent of chronic respiratory disease in chickens. Live attenuated vaccines are most commonly used in the field to control the disease, but current vaccines have some limitations. Vaxsafe MG (strain ts-304) is a new vaccine candidate that is efficacious at a lower dose than the current commercial vaccine strain ts-11, from which it is derived. In this study, the transcriptional profiles of the trachea of unvaccinated chickens and chickens vaccinated with strain ts-304 were compared 2 weeks after challenge with M. gallisepticum strain Ap3AS during the chronic stage of infection. After challenge, genes, gene ontologies, pathways, and protein classes involved in inflammation, cytokine production and signaling, and cell proliferation were upregulated, while those involved in formation and motor movement of cilia, formation of intercellular junctional complexes, and formation of the cytoskeleton were downregulated in the unvaccinated birds compared to the vaccinated birds, reflecting immune dysregulation and the pathological changes induced in the trachea by infection with M. gallisepticum. Vaccination appears to protect the structural and functional integrity of the tracheal mucosa 2 weeks after infection with M. gallisepticum.

The survival, replication, and virulence of mycoplasmas depend on their ability to capture and import host-derived nutrients using poorly characterized membrane proteins. Previous studies on the important bovine pathogen Mycoplasma bovis demonstrated that the amino-terminal end of an immunogenic 226-kDa (P226) protein, encoded by milA (the full-length product of which has a predicted molecular weight of 303 kDa), had lipase activity. The predicted sequence of MilA contains glycosaminoglycan binding motifs, as well as multiple copies of a domain of unknown function (DUF445) that is also found in apolipoproteins. We mutagenized the gene to facilitate expression of a series of regions spanning the gene in Escherichia coli. Using monospecific antibodies against these recombinant proteins, we showed that MilA was proteolytically processed into 226-kDa and 50-kDa fragments that were both partitioned into the detergent phase by Triton X-114 phase fractionation. Trypsin treatment of intact cells showed that P226 was surface exposed. In vitro, the recombinant regions of MilA bound to 1-anilinonaphthalene-8-sulfonic acid and to a variety of lipids. The MilA fragments were also shown to bind heparin. Antibody against the carboxyl-terminal fragment inhibited the growth of M. bovis in vitro. This carboxyl end also bound and hydrolyzed ATP, suggestive of a potential role as an autotransporter. Our studies have demonstrated that DUF445 has lipid binding activity and that MilA is a multifunctional protein that may play multiple roles in the pathogenesis of infection with M. bovis.

No abstract

No abstract

Tracheitis associated with the chronic respiratory disease in chickens caused by Mycoplasma gallisepticum is marked by infiltration of leukocytes into the mucosa.Although cytokines/chemokines are known to play a key role in the recruitment, differentiation, and proliferation of leukocytes, those that are produced and secreted