Streptococcus suis isolates from porcine endocarditis

Streptococcus suis is a zoonotic pathogen that causes a wide range of clinical disease syndromes in pigs, other animals, and humans. This bacterium affects pigs in farms causing meningitis, pneumonia, septicemia, arthritis, etc., whereas clinically healthy pigs were sometimes found in slaughter houses to be suffering from endocarditis. S. suis produces polysaccharide capsule (cap) which is synthesized by series of enzymes encoded on capsular polysaccharide synthesis (cps) genes. Cap of S. suis confers an ability to resist phagocytosis during the development of diseases. Therefore, cap is believed to be one of the important virulence factors of S. suis. However, we have found that both cap-positive and -negative isolates were found in porcine endocarditis and cap-negative isolates showed a high degree of ability to adhere to platelets. Here we compared genome sequences of multiple numbers of cap-negative isolates from the lesions of endocarditis. Comparisons of the cps genes and whole genome sequences enabled us to speculate how these mutants arose and why they still inhabited in there.