Aug 2026· Fishes· Vol 11, pp. 480· 0 citations· 44 references
TL;DR
Results demonstrate that LvCTL functions as an important immune recognition molecule and contributes to antibacterial defense against V. parahaemolyticus in L. vannamei.
Abstract
C-type lectins (CTLs) are important pattern recognition receptors (PRRs) involved in innate immune defense in crustaceans. In this study, a novel C-type lectin, designated LvCTL, was identified and functionally characterized from Litopenaeus vannamei. Sequence analysis revealed that the open reading frame (ORF) of LvCTL is 495 bp in length and encodes a 164-amino acid polypeptide containing a typical C-type lectin-like domain but lacking the classical carbohydrate-binding motifs. Notably, two novel EPF motifs were identified in the CTLD region, suggesting a potential non-canonical ligand recognition pattern. Phylogenetic analysis revealed that LvCTL clustered with other crustacean CTLs. Tissue expression analysis revealed that LvCTL exhibited the highest transcript level in the hepatopancreas. After immune stimulation, LvCTL expression in the hepatopancreas was significantly regulated by LPS, Vibrio parahaemolyticus, Staphylococcus aureus, WSSV and Poly(I: C), indicating its involvement in antimicrobial immune responses. RNA interference assays showed that knockdown of LvCTL significantly increased the bacterial burden and reduced the survival rate of shrimp after V. parahaemolyticus infection. Furthermore, recombinant LvCTL displayed broad bacterial binding activity to Gram-negative and Gram-positive bacteria and induced calcium-dependent agglutination of V. parahaemolyticus and S. aureus. Taken together, these results demonstrate that LvCTL functions as an important immune recognition molecule and contributes to antibacterial defense against V. parahaemolyticus in L. vannamei. These findings broaden our understanding of the functional diversity of shrimp CTLs and their contributions to crustacean innate immunity.
C-type lectins (CTLs) are vital pattern-recognition receptors (PRRs) that mediate innate immune responses in mollusks, yet their characterization in Caenogastropoda, the largest gastropod group, remains limited. This study characterizes LitCTL1, a novel secreted single-domain C-type lectin from the common periwinkle, Littorina littorea. The 199-amino acid polypeptide contains a conserved carbohydrate recognition domain with canonical QPD and WND motifs and is predicted to form a homodimer. Uniquely, LitCTL1 was localized in both circulating hemocytes and mucus-secreting epithelial cells of the foot, mantle, and hypobranchial gland - the first report of such dual localization for a molluscan lectin, linking systemic and mucosal defense. Expression analysis revealed that LitCTL1 is constitutively expressed in hemocytes. Functional assays with recombinant LitCTL1 demonstrated its role as a potent opsonin with hemagglutinating activity, significantly enhancing hemocyte spreading and the phagocytosis of zymosan. Genomic analysis reveals that LitCTL1 belongs to a rapidly diversifying, genus-specific expansion distinct from conserved perlucin-like lineages. These results identify LitCTL1 as a key effector molecule in both systemic and mucosal innate immunity, likely reflecting an evolutionary adaptation to the microbial challenges of the intertidal environment.
Alexander Gorbushin, E. Borisova· Fish and Shellfish Immunolog...· 0 citations
A novel piscidin was identified in largemouth bass that contained an active peptide of 25 aa with an amphipathic helix possessing distinct hydrophobic and positively charged regions, and was significantly up-regulated in spleen from 6 h to 24 h post-lipopolysaccharide (LPS) stimulation.
Five core genes associated with the NLRP3 inflammasome pathway in golden pompano showed inducible and tissue-dependent expression patterns, supporting their involvement in the antibacterial immune response, and provide a basis for understanding inflammasome-related immunity in golden pompano.
Zheng-Jing Lin, Xue-Mei Mou, Peng Xu et al.· Fish and Shellfish Immunolog...· 0 citations
Results demonstrate that LcELAVL1a functions as an immune-active protein in large yellow croaker and provide new insights into the functional diversity of the ELAVL family in teleost fish.
Jiaxin Song, Rumeng Zhai, Dianyang Zhou et al.· Fish and Shellfish Immunolog...· 0 citations
The RelA subunit is a core component of the nuclear factor-kappa B (NF-κB) family and plays a pivotal role in regulating immune and inflammatory responses across vertebrates and invertebrates. However, its functional role remains poorly defined in marine bivalves. In this study, a RelA homolog (RpRelA) was identified and functionally characterized in the Manila clam (Ruditapes philippinarum). The full-length cDNA of RpRelA is 2055 bp, encoding a 684-amino acid protein containing a conserved Rel homology domain (RHD) and an IPT domains. Both its tertiary structure and amino acid sequence are highly conserved across species. Phylogenetic analysis indicated that RpRelA clusters with invertebrate Rel family members. Quantitative real-time PCR (qRT-PCR) revealed that RpRelA is ubiquitously expressed in all examined tissues, with the highest expression levels detected in haemocytes and gills. Following V. parahaemolyticus challenge, both the mRNA and protein levels of RpRelA were significantly upregulated. Consistently, nuclear-cytoplasmic fractionation Western blot and immunofluorescence analyses confirmed its robust nuclear translocation upon bacterial infection. Furthermore, overexpression of RpRelA significantly upregulated pro-inflammatory genes (RpIL-17 and RpTNF) and caused severe gill inflammation, whereas its silencing suppressed their expression and alleviated the inflammatory response. Collectively, these results demonstrate that RpRelA, as a core NF-κB subunit, positively regulates the inflammatory response during V. parahaemolyticus infection in Manila clam, and provide new insights into the immune regulatory mechanism of bivalves against bacterial infection.
Hao-Dong Feng, Tian Yu, Jia-Xi Liang et al.· Fish and Shellfish Immunolog...· 0 citations
To investigate the pathogen-associated molecular recognition characteristics and immune response of Toll-like receptor 22 (TLR22) in Micropterus salmoides, sequence characterization was performed, and its potential immune functions were further evaluated through tissue expression profiling, pathogen-associated stimulation response analysis, recombinant protein binding assays, and in vivo challenge experiments. The results showed that the open reading frame of TLR22 in M. salmoides was 2880 bp in length and encoded 959 amino acids. The deduced protein exhibited the typical structural features of teleost TLR22 and showed high sequence homology with TLR22 from other teleost species. TLR22 was expressed in all examined tissues, with relatively high expression levels in the head kidney and spleen. Stimulation with poly(I:C), lipopolysaccharide (LPS), and Aeromonas hydrophila significantly induced temporal changes in TLR22 expression in the head kidney, liver, and spleen. Recombinant TLR22 protein was able to bind multiple bacterial species and pathogen-associated molecular patterns, and displayed differential binding activities toward different ligands. In vivo challenge experiments showed that pretreatment with recombinant TLR22 protein enhanced the expression responses of immune-related genes, including TLR22, traf6, IL-6, IL-1β, and hepcidin, in relevant tissues following A. hydrophila infection. The TLR22-Ah group also exhibited a numerically higher final survival rate than the PBS-Ah and TrxA-Ah groups, although the pairwise differences were not statistically significant. Collectively, these results suggest that TLR22 in M. salmoides may participate in pathogen stimulus-induced innate immune responses and play important roles in pathogen recognition and immune regulation. This study provides a basis for further elucidating the immunological function of TLR22 in M. salmoides.
Ke Wang, Ling-Yun Lu, Yu Liu et al.· Developmental and Comparativ...· 0 citations
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