Experimental vaccination against Mycoplasma agalactiae using different inactivated vaccines

Five sets of vaccines were prepared using Mycoplasma agalactine washed cult ures inactivated with phenol (1), formalin (2), heat-treatment (3), sodium hypochlorite (4) and saponin (5). All sets, except for saponin-vaccine, wer e adjuvated with aluminium hydroxide. Five groups of six sar ewes were inoc ulated twice before pregnancy, once during pregnancy and challenged during the lactation period. Monthly blood samples were taken from the vaccinated sheep and from 12 controls: sera were assayed by immunoblotting, ELISA and growth inhibition tests. Four control sheep were infected by intracanalicul ar route with pooled mycoplasmas at concentrations of 10(4), 10(5), 10(6) a nd 10(7) CCU. The challenge involved using infested milk to contaminate the remaining sheep. All the controls and some ewes from groups 2, 3 and 4 dev eloped contagious agalactia. Ewes vaccinated with phenol- and saponin-inact ivated mycoplasmas resisted experimental challenge. These results suggest t hat these two vaccines are effective and that their use could limit the dif fusion of M. agalactiae infection. (C) 1999 Elsevier Science Ltd. All right s reserved.