Evidence indicating the existence of a novel family of serine protease inhibitors that may be involved in marine invertebrate immunity

Transcriptomics of In Vitro Immune-Stimulated Hemocytes from the Manila Clam Ruditapes philippinarum Using High-Throughput Sequencing

“…Because protease inhibitors play important roles in invertebrate immunity by protecting hosts through the direct inactivation of pathogen proteases, many bivalves have developed protease inhibitors to regulate the activities of pathogen proteases [1]. Some genes encoding protease inhibitors were identified in C. gigas [57], A. irradians [58], C. farreri [59] and C. virginica; in the latter a novel family of serine protease inhibitors was also characterized [60][61][62].…”

Upregulation in response to infection and antibacterial activity of oyster histone H4

“…Other antimicrobial molecules discovered in oysters include C. virginica plasma lysozyme [12], C. gigas bactericidal/permeability-increasing protein [13], and peptidoglycan recognition proteins, which are speculated to have antimicrobial properties [14]. Serine protease inhibitors cvSI-1 and cvSI-2 may also play a role in C. virginica host defense against P. marinus proliferation [15,16].…”

Disk abalone (Haliotis discus discus) expresses a novel antistasin-like serine protease inhibitor: Molecular cloning and immune response against bacterial infection

“…SPIs in mollusks were identified in hemolymph as a group of humoral factors of the Pacific oyster, Crassostrea gigas, Eastern oyster, Crassostrea virginica [30], softshell clam, Mya arenaria [31] and surf clam, Spisula solidissima [32]. There is also evidence supporting the role of SPIs in immunity, such as is exhibited by cvSI-1 and cvSI-2 from C. virginica [28,29] and Argopecten irradians AISPI [33]. Even though a few mollusk SPIs have been isolated and characterized at the molecular and functional level, no evidence of an antistasin-like protease inhibitor has been reported.…”