serogeen

Serogeen, or serogroup (in Dutch: serogeen), is a classification used in microbiology to describe a group of organisms within a single species that share a common set of surface antigens. These antigens are typically polysaccharides or proteins on the cell surface and are recognized by specific antibodies. Serogeen are defined by serological testing and are used to track epidemiology, design vaccines, and study antigenic diversity.

Classification is usually determined by serological assays that detect reactions with antisera against the target surface antigen, such as agglutination tests or ELISA. In practice, molecular methods that analyze genes encoding surface structures, such as capsule (capsular polysaccharide) or O antigens, can substitute or complement traditional serology when antisera are unavailable.

Serogeen are distinct from serotypes or serovars, which refer to more specific antigenic properties within a serogroup. A single species may contain many serogeen but fewer serotypes, or vice versa, depending on the organism and the nomenclature used. In public health, serogeen information guides surveillance and vaccine strategy. For example, Neisseria meningitidis is classified into serogeen A, B, C, W, and Y based on the capsule; vaccines target several of these serogeen. Escherichia coli and Salmonella are also typed by serogeen based on O antigens, supporting outbreak investigations and prevention efforts.

Limitations include antigenic variation and cross-reactivity, which can complicate serogeen assignment. Molecular typing has become a common complement to serology, offering a more precise and stable classification.