Characterization of a Mycoplasma Pneumoniae CARDS Toxin Mutant

Mycoplasma pneumoniae is a high-burden pathogen which causes mild to significant infections of the respiratory system. According to the CDC, an estimated two million cases occur yearly in the United States alone, demonstrating the widespread effect of the pathogen. In addition to being the cause of respiratory infections, M. pneumoniae has also been implicated in exacerbating pre-existing asthma conditions. These morbidities make finding a vaccine candidate a vital part of easing the healthcare burden caused by the pathogen. The current mechanism of infection is unknown, but recent evidence points to the Community Acquired Respiratory Distress Syndrome (CARDS) toxin as being involved in that mechanism. We believe that if a mutant was created that was attenuated for the CARDS toxin, then the virulence will be diminished. This will provide further evidence to the theory that the CARDS toxin is responsible for the pathogenesis of the bacteria. In this experiment, we isolated a M. pneumoniae mutant and placed it in a mouse model to test for virulence. After using transposon insertion to find a possible mutant, polymerase chain reaction (PCR) was run to confirm the insertion of the transposon. The mutant was then placed in a mouse model to compare its virulence with that of wild-type M. pneumoniae. When placed in the model, the mutant M. pneumoniae-infected mice had lower lesion scoring and lower bacterial counts in serial dilutions than those of the wild-type M. pneumoniae. This gave proof that the isolated mutant was in fact attenuated for virulence. Further steps must be taken to ascertain the identity of the mutant, such as DNA sequencing and in vitro studies. Given the results, this experiment was a success in isolating a virulence-attenuated M. pneumoniae mutant, and is a step closer to finding a possible vaccine for the disease