Bivalves Humoral Immunity: Key Molecules and Their Functions

This review presents the basic concepts and knowledge about the immunity of Bivalvia with an emphasis on humoral factors and a more detailed analysis of carbohydrate-binding and effector molecules, an assessment of the influence of environmental factors on their activity, and a description of application of some of them. Cellular responses and hemocytes are briefly considered as a key component of the bivalve immune system and the main source of protective molecules. Various types of classification of humoral immunity factors are provided with their further description for groups based on functional activity. Carbohydrate-binding proteins that recognize foreign components and play the role of agglutinins and opsonins, general regulatory mechanisms and signal molecules, as well as effector molecules such as lysins, antimicrobial peptides, etc. are considered in detail.