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Doser, Susanne (2008): Untersuchung zur Möglichkeit einer Vakzination gegen Mycoplasma suis. Dissertation, LMU München: Faculty of Veterinary Medicine
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Abstract

Investigation for the possibility of a vaccination against Mycoplasma suis Porcine eperythrozoonosis caused by Mycoplasma suis is a globally distributed disease of economic impact. Since M. suis cannot be cultivated in vitro the development of suitable vaccines is difficult. In this work, an M. suis vaccination study was performed using recombinant MSG1 (rMSG1), one of three major M. suis immunogens. Since non-adhesive E. coli gain adhesive properties through MSG1 expression, recombinant E. coli were used as vaccine antigens too. Two test groups with rMSG1, one with singular (MSG1Prot1) and one with double the amount of proteins (MSG1Prot2), as well as two test groups with recombinant E. coli serving as a vaccine antigen in singular (MSG1Coli1) and double dosis (MSG1Coli2) were applied. Control vaccination groups received purified control protein (pBAD_without insert, purified), an E. coli control (E. coli_pBAD_without insert) and adjuvans alone. Twenty five experimental pigs were vaccinated at an age of three weeks (day 0) and at an age of six weeks (day 21). For the first vaccination complete Freund adjuvant and for the second vaccination incomplete Freund adjuvant was used. All animals were splenectomised between day 29 and 32. To check protection potential of the vaccination the pigs were given a challenge infection on day 35. During said test phase the pigs were tested weekly up to the 84th test day. Besides clinical examinations temperature was measured twice daily in order to determine their health status. Furthermore, local irritation and damage due to vaccination were measured by adspection and palpation. Tissue irritations and damage were the same for all animal groups. These changes were obviously stronger after the second vaccination than after the first vaccination. The humoral immune response was determined by recombinant ELISA systems. MSG1 specific antibodies were determined for all immunisation groups 21 days after the first vaccination at latest. After the second vaccination the immune response was boostered. In addition, a cellular immune response was determined by applying a T-cell proliferation test. The test infection caused an acute eperythrozoonosis with the vaccinated as well as with the non-vaccinated pigs. Haematologic results and the M. suis-load/ ml blood do not show significant differences amongst the individual test groups and control groups. Merely the MSG1Coli2 vaccination group tends to show protection potency due to the vaccination and antigen used. This work represents the foundation for further studies towards developing a vaccine against M. suis. Now the initial aim must focus on searching for further vaccine candidates and state-of-the-art strategies.