A critical review speculating on the protective efficacies of autogenous Streptococcus suis bacterins as used in Europe

Table 1 Immunogenicities and protective efficacies of S. suis serotypes 2 and 9 bacterins after prime-boost vaccination of weaning piglets and homologous challenge experiments using the same oil-in-water adjuvant (Emulsigen) [6, 41]

Genotype of the bacterin and the challenge strain	mrp + epf + sly + cps2-		mrp* sly + cps9
Genotype of the bacterin and the challenge strain	bacterin	placebo	bacterin	placebo
MRP-ELISA^a,b	500 Units	5 Units	100 Units	25 Units
Mean bacterial survival factor in opsonophagocytosis assays^b,c	0.4	1.6	0.78	1.18
Mortality	28.6%	87.5%	22.2%	77.8%
Morbidity	28.6%	100%	77.8%	100%
Pathohistological score^d of infected piglets	1.25	3.75	2.8	3.8

^aUsing rMRP of serotype 2 strain 10 as antigen
^bThese assays were conducted with samples collected 2 weeks after the boost vaccination and prior to the experimental infection
^cSurvival factors were determined by dividing the number of colony forming units (CFUs) after a 2 h incubation period at 37 °C by the number of CFUs at t = 0
^dFor calculation of the pathohistological score the sum of the highest scores of each animal for any of the investigated organs was divided by the number of animals (ω = Σscore_max/n_animals)

ISSN: 2055-5660