Genetic Studies of the Effect of Serotype Switching in O1 Vibrio cholerae
Examensarbete för masterexamen
Cholera is still today a severe disease causing millions of infections world-wide. The causative pathogenic bacteria presents as two main serotypes: Ogawa and Inaba. The serotypes differ in the methylation of a surface sugar that is mediated by the wbeT gene, with Ogawa having an active intact gene and Inaba having an inactive mutated gene, giving loss-of-function. The aim of this project was to construct an Inaba strain from an Ogawa strain, making a pair of otherwise isogenic strains. Moreover, the project aimed to use the strains to investigate differences between the serotypes. The construction of the Inaba strain was successful, and the pair of strains are now used for study. No noteworthy differences in growth rate between the serotypes was found when grown in isolation, but when grown together in liquid culture the serotypes reached an equilibrium of 80% Ogawa to 20% Inaba. One experiment to illustrate serotype switching by applying a selection pressure using antibodies was performed. The experiment generated 8 novel Inaba mutations, one of which is most likely a very stable Inaba mutant that could also be used as part of an isogenic pair together with its parent strain. Further studies into the differences between the serotypes is warranted, and the two pairs of isogenic strains can be interesting tools for such research.
Cholera , serotype , Inaba , Ogawa , genetic engineering , vibriocide , co-culture