A review of vaccine development and research for industry animals in Korea

Lee, Nak-Hyung; Lee, Jung-Ah; Park, Seung-Yong; Song, Chang-Seon; Choi, In-Soo; Lee, Joong-Bok

Conjugated vaccines are somewhat similar to recombinant subunit vaccines, which are usually composed of two different components. They have been generated against pathogens whose polysaccharide capsule protect them from the phagocytosis. Since the polysaccharide is poorly immunogenic, linking the polysaccharide to immunogenic protein enables the immune system to recognize them as if they were protein antigens. They are produced by chemically linking the polysaccharide to a carrier protein, which creates stronger, combined immune responses to the piece derived from bacteria as well as the carrier protein. Immunity to a piece of the bacteria can protect from future infection. Such types of vaccines are currently in use for Streptococcus pneumoniae. In contrast, some bacterial diseases are not directly caused by bacteria themselves but by a toxin produced by the bacteria. Tetanus is caused by neurotoxin that is produced by Clostridium tetani, rather than bacterial infection. Vaccines for this type of pathogen can be generated by inactivating the toxin responsible for causing clinical signs. As with the other pathogens used for killed vaccines, the inactivation process can be performed via treatment with heat or chemicals, or other suitable means. Although inactivated toxin could be considered a killed vaccine, sometimes it should be in its own category to highlight that it contains an inactivated toxin but not bacteria.