Allestimento e test in vivo di un vaccino a DNA contro l'Agalassia Contagiosa

<i>Mycoplasma agalactiae</i> is the aetiological agent of Contagious Agalactia (CA), an economically detrimental disease affecting small ruminants worldwide. The control of <i>M. agalactiae</i> through vaccination is an increasing challenge. Although several inactivated vaccines have proved effective in conferring protection against CA, they carry intrinsic disadvantages and only produce a short-lived humoral immune response. A DNA vaccine against CA has been developed encoding the P48eof Mycoplasma agalactiae inducing the immune responses in BALB/c mice (Chessa <i>et al</i>., 2009). In this study, the vaccinal plasmid pJW/tPA/rP48 expressing the P48 of <i>M. agalactiae</i> in fusion with the signal peptide of tissue plasminogen activator (tPA) was designed and evaluated <i>in vivo</i>. Initially, the production of P48 was evaluated in HEK 293 cells by rtPCR and by Western blotting. A field trial was performed by immunizing sheep by injecting them both with recombinant P48 protein and the plasmid pJW/tPA/rP48. Results demonstrated the production of P48-specific antibodies in immunized sheep, confirming that P48 was expressed and induced significant immune responses. Also we showed that immunization can negatively affect milk-shedding of microorganisms, especially when a prime boost strategy is used. Concluding, it has been demonstrated that even if immunization against rP48 alone induce a significant immune response it does not protect sheep against CA.