Thesis (M.Sc.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

In the present work Streptococcus species have been isolated from horses clinically suffering from strangles disease. The isolated streptococci were identified using bacteriological and molecular techniques. One isolate was identified as S. equi subsp. equi and the other 4 isolates were identified as streptococcus equi subsp. zooepidemicus. The isolated streptococcal species were used to develop vaccine against strangles disease. Also two types of adjuvants were investigated and compared as immuno-potentiating agents, namely montanide gel and ISA 70. Four vaccine formulations were prepared and its immunizing efficacy was investigated. The first two vaccine formulations were composed only from streptococcus equi subsp. equi; the first one was adjuvanted with Montanide gel and the second with ISA70. The other two vaccine formulations were combined vaccines composed from both the Streptococcus equi subsp. equi and streptococcus equi subsp. zooepidemicus. These 2 vaccine formulations were adjuvanted with montanide gel (the third vaccine formulation) or with ISA70 (the fourth formulation). Using passive hemagglutination test and ELISA significant specific antibody titers have been measured in the immunized mice, rabbits and donkeys. The combined vaccine proved more effective than the monovalent one. Also ISA 70 adjuvant was better than the Montanide gel one. In challenge test in immunized mice with virulent S. equi subsp. equi, 55% protection rate was recorded

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