ANTIVIRAL ACTIVITY OF GALECTIN-1 FROM ROCK BREAM Oplegnathus fasciatus AGAINST TWO POTENTIAL PISCINE VIRUSES

Galectins are a family of lectins characterized by their affinity to β-galactosides. Among the galectin family members, galectin-1 from mammals is reported to directly bind with several enveloped viruses and thereby facilitate or inhibit the infectivity of virus. In the present study, we identified a galectin-1 from rock bream Oplegnathus fasciatus designated as OfGal-1 and tested its antiviral activity against two enveloped piscine viruses, rock bream irido virus (RBIV) and virus hemorrhagic septicemia virus (VHSV).

The open reading frame of the OfGal-1 was identified from the cDNA library, cloned into pMALc2x protein expression vector, and the maltose binding protein (MBP)-fused recombinant protein (rOfGal-1) was purified by column chromatography. Carbohydrate specificity of rOfGal-1 was tested by inhibition of hemagglutination. Antiviral activity of the rOfGal-1was tested by treating the rock bream heart cells and FHM cells with RBIV and VHSV, respectively with rOfGal-1. Recombinant MBP was used as control. Inhibition of cytopathic activity was observed under microscope and the cell viability was estimated spectrophotometrically using WST-1 cell-proliferation assay kit 72 h post viral treatment.

The rOfGal-1 showed strong hemagglutination with human erythrocytes and showed high affinity to α-lactose and β-galactose. When the heart cells treated with RBIV, no significant difference (p < 0.05) was observed between (virus-treated) control and MBP (25 µg/ mL); meanwhile, treatment with RBIV along with rOfGal-1 (25 µg/ mL) showed significant protective activity (p < 0.05) (Fig. 1A). Meanwhile, treatment with VHSV on FHM cells along with rOfGal-1 (25 µg/ mL) also showed a significant (p < 0.05) protective activity or inhibition of cytopathic activity, however the viability was less than the untreated FHM cells.

The results from the present study suggests that similar to other vertebrate galectin-1 homologs, OfGal-1 might bound with these two enveloped viruses and hence play a significant role on the pathogenicity of RBIV and VHSV.