Abstract
Lectin sensitivity of the recent pandemic influenza A virus (H1N1-2009) was screened for 12 lectins with various carbohydrate specificity by a neutral red dye uptake assay with MDCK cells. Among them, a high mannose (HM)-binding anti-HIV lectin, ESA-2 from the red alga Eucheuma serra, showed the highest inhibition against infection with an EC50 of 12.4 nM. Moreover, ESA-2 exhibited a wide range of antiviral spectrum against various influenza strains with EC50s of pico molar to low nanomolar levels. Besides ESA-2, HM-binding plant lectin ConA, fucose-binding lectins such as fungal AOL from Aspergillus oryzae and AAL from Aleuria aurantia were active against H1N1-2009, but the potency of inhibition was of less magnitude compared with ESA-2. Direct interaction between ESA-2 and a viral envelope glycoprotein, hemagglutinin (HA), was demonstrated by ELISA assay. This interaction was effectively suppressed by glycoproteins bearing HM-glycans, indicating that ESA-2 binds to the HA of influenza virus through HM-glycans. Upon treatment with ESA-2, no viral antigens were detected in the host cells, indicating that ESA-2 inhibited the initial steps of virus entry into the cells. ESA-2 would thus be useful as a novel microbicide to prevent penetration of viruses such as HIV and influenza viruses to the host cells.
Highlights
Influenza viruses cause annual epidemics and occasional global pandemics
We employed neutral red (NR) dye uptake assay using the clinical isolates of H1N1-2009 virus, A/Oita/OU1 P3-3/09
We have previously demonstrated that ESA-2 has four binding sites in its molecule that are built from four tandem repeats with characteristic homologous sequence in this lectin family [13]
Summary
Influenza viruses cause annual epidemics and occasional global pandemics. The viral envelope glycoprotein HA (hemagglutinin) functions to bind to cellular receptors and mediate fusion with endosomal membranes [1]. The recently discovered HM-binding lectin family from lower organisms such as bacteria, cyanobacteria, and marine algae represents a novel class of antiviral compounds This family includes cyanobacterial lectin: OAA from Oscillatoria agardhii [7,8,9,10] and its homologous proteins such as bacterial lectin: PFL from Pseudomonas fluorescens Pf0-1 [11] and BOA from Burkholderia oklahomensis [12], red algal lectins: ESA-2 from Eucheuma serra [13] and KAA-2 from Kappaphycus alvarezii [14]. The molecular basis of anti-influenza activity of ESA-2 was evaluated from the aspects of lectin-envelope glycoprotein interactions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
