Updating the proteome of the uncultivable hemotrophic Mycoplasma suis in experimentally infected pigs.

Mycoplasma suis belongs to the hemotrophic mycoplasmas that are associated with acute and chronic anemia in a wide range of livestock and wild animals. The inability to culture M. suis in vitro has hindered its characterization at the molecular level. Since the publication of M. suis genome sequences in 2011 only one proteome study has been published. Aim of the presented study was to significantly extend the proteome coverage of M. suis strain KI_3806 during acute infection by applying three different protein extraction methods followed by 1D SDS-PAGE and LC-MS/MS. A total of 404 of 795 M. suis KI_3806 proteins (50.8%) were identified. Data analysis revealed the expression of 83.7% of the predicted ORFs with assigned functions but also highlights the expression of 179 of 523 (34.2%) hypothetical proteins with unknown functions. Computational analyses identified expressed membrane-associated hypothetical proteins that might be involved in adhesion or host-pathogen interaction. Furthermore, analyses of the expressed proteins indicated the existence of a hexose-6-phosphate-transporter and an ECF transporter. In conclusion, our proteome study provides a further step toward the elucidation of the unique life cycle of M. suis and the establishment of an in vitro culture. All MS data have been deposited in the ProteomeXchange with identifier PXD002294 (http://proteomecentral.proteomexchange.org/dataset/PXD002294).

Quantitative PCR analysis of Mycoplasma suis shedding patterns during experimental infection.

The uncultivable hemotrophic bacterium Mycoplasma suis causes infectious anemia in pigs worldwide. The mechanisms by which M. suis is transmitted from pig to pig are largely unknown. Thus, the present study aimed at investigating urine, feces, saliva, nasal and vaginal secrets as well as environmental samples for the presence of M. suis DNA to get insights into potential transmission routes. Seven pigs were experimentally infected with M. suis KI3806. Samples were taken for 8 days post infection (p.i.). A quantitative LightCycler msg1 PCR was used to detect and quantify M. suis. Shedding was found in saliva as well as nasal and vaginal secrets from day 6 p.i. on with a quantity of 3.4 × 10(2) to 2.7 × 10(5)M. suis/swab. In urine M. suis DNA could be detected in 100.0% of the samples from day 6 p.i. on with a quantity of 4.7 × 10(2) to 6.3 × 10(5)M. suis per mL. When shedding patterns were correlated to the median bacterial blood loads shedding was observed at loads of 2.0 × 10(9)-7.0 × 10(10)M. suis per mL blood. No M. suis DNA could be amplified from feces. Dust and water samples of the pig drinking troughs were positive for M. suis on days 2 and 6 post infection, air samples were M. suis-negative throughout the experiment. Our results indicate that blood independent direct transmission as well as indirect transmission via environmental contamination could play a role in the epidemiology of M. suis infections.