Fig. 4

Results of histopathological examination. Piglets from sows with or without prepartum immunization with inactivated S. suis 2 + rSao were challenged with (a) heterologous S. sui serotype 1 and (b) homologous S. sui serotype 2 bacteria at the 5 weeks of age. The histopathological examination was performed on the 7^th day after the challenge. Control pigs manifested severe brain and lung lesions, including slight vascular congestion on the brain meninges and shedded epithelial cells in the lung alveolar space