Introduction on the Features and Functions of Down Syndrome Cell Adhesion Molecule (Dscam) in Crustacean Immune System as a Quasi-Specific Humoral Agent

Acquired immunity is reported only in vertebrates. However, nowadays, the available evidence shows that a kind of quasi-specific immunity and also an immune memory exists in crustaceans. This process is explained by several mechanisms, the most important of which are some humoral immune factors such as lectin and Dscam. Down syndrome cell adhesion molecules (Dscam) are kinds of pathogen-dependent molecules that are produced during exposure of some invertebrates to pathogens (antigens). Vaccine-like agents may be synthesized to act as activators and activate this immune mechanism in shrimp through antigens, and consequently, make a kind of immunogenicity. It is not as accurate as vertebrates’ immune system and the secretion of antibodies and can lead to relatively specific immunizations in crustaceans. Nevertheless, the corresponding immunization practically decreases the economic losses of the shrimp industry. Hence, we recommend the health management of the shrimp farms should not focus only on the production of specific pathogen-free larvae by relevant institutions or the implementation of biosecurity guidelines by farmers, but in order to prevent the infectious agents in shrimp farms, the novel solutions in this context should be developed.