In the present study, two C-type lectins (designated as VpClec-3 and VpClec-4) were identified and characterized from the manila clam Venerupis philippinarum. Multiple alignment and phylogenetic relationship analysis strongly suggested that VpClec-3 and VpClec-4 belong to the C-type lectin family. In nonstimulated clams, the VpClec-3 transcript was dominantly expressed in the hepatopancreas, while the VpClec-4 transcript was mainly expressed in gill tissues. Both VpClec-3 and VpClec-4 mRNA expression was significantly upregulated following Vibrio anguillarum challenge. Recombinant VpClec-4 (rVpClec-4) was shown to bind lipopolysaccharide (LPS) and glucan in vitro, whereas recombinant VpClec-3 (rVpClec-3) only bound to glucan. In addition, rVpClec-3 and rVpClec-4 displayed broad agglutination activities towards Vibrio harveyi, Vibrio splendidus and V. anguillarum, while no agglutination activities towards Enterobacter cloacae or Aeromonas hydrophila were observed in rVpClec-3. Moreover, hemocyte phagocytosis was significantly enhanced by rVpClec-3 and rVpClec-4. All the results showed that VpClecs function as pattern recognition receptors (PRRs) with distinct recognition spectra and are potentially involved in the innate immune responses of V. philippinarum.
Bibliographical noteFunding Information:
This research was supported by grants from the Strategic Priority Research Program of the Chinese Academy of Sciences ( XDA23050303 ), the National Natural Science Foundation of China (No. 41806196 ; 41506190 ), Natural Science Foundation of Shandong Province ( ZR2019BD022 , ZR2017MC045 ), Yantai Science and Technology Development Project ( 2020MSGY066 ) and Marine and Fisheries Science and Technology Innovation Program of Shandong ( 2017YY04 ).
© 2020 Elsevier Ltd
- C-type lectin
- Immune recognition
- Molecular characterization
- Venerupis philippinarum