Fig. 4
Protectiveness of vaccine samples at different doses in guinea pigs. a–c Colonization of B. melitensis in organs and tissues of prime-boost vaccinated guinea pigs and c index of Brucella infection upon challenge with B. melitensis 16 M. Guinea pigs were immunized twice i.n. 21 days apart with a new vaccine candidate at dose 105 EID50, 106 EID50 and 107 EID50 or a single delivery of commercial vaccine B. melitensis Rev.1. via s.c. immunization. Guinea pigs of positive control groups were injected with PBS. Animals challenged with virulent strain of B. melitensis 16 M at a dose of 20 CFU/animal using s.c. route. Bacteriological evaluation was assessed by counting Brucella colonies in tissues, where data is expressed as log10 CFU/g and the index of infection of infected animals and compared to the control groups (the arithmetic mean ± standard error was given for each group; number of tissues from where Brucella was isolated for each animal). Statistical analysis for (A-C) was performed using a one-way ANOVA followed by Dunnett's multiple comparisons test and for (D) using two-way ANOVA, Tukey’s multiple comparisons test