<strong></strong>Evaluation of Complex Carbohydrates Showing Broad-Spectrum Antiviral Activity against SARS-CoV-2, Influenza-a (H1N1) and Human Respiratory Syncytial Virus (hRSV) Strain A2 in ‘In Vitro’ Setting
Authors: Platt David , Sigamani Alben , Shah Nehal 
Published: September 2023

ntroduction: Respiratory tract Infections are the greatest cause of death worldwide. Since its outbreak in 2019, the coronavirus pandemic (COVID-19) has been a challenge to humans in terms of treatment and prevention of this respiratory viral infection. The re-emergence of respiratory viral infections like influenza, pose a serious hazard to global public health because they occur seasonally. Creating broad-spectrum antiviral compounds for rapid action in the case of an outbreak crisis, as well as bioweapon defences, is critical. Human galectin-3 is found in high concentrations in activated T lymphocytes, epithelial and endothelial cells, and fibroblasts. ProLectin -I and ProLectin -M are both galectin antagonists. Blocking viral entry with a complex polysaccharide component "ProLectin-M" has downstream effects on viral reproduction enabling it to be used as a therapeutic tool and a safe alternative to conventional anti-viral medicines. Methods: In total, 3 cell based assays have been conducted to evaluate antiviral efficacy of ProLectin&ndash;I and ProLectin-M against SARS-CoV-2 virus, Influenza-A (H1N1), and human respiratory syncytial virus (hRSV) strain A2. ProLectin-M and ProLectin-I were evaluated for their anti-viral potency using SARS-CoV2 virus strain by viral RNA Extraction and qRT-PCR assays. The plaque assays were carried out to determine the antiviral activity of the test products (ProLectin-I and ProLectin-M) against &lsquo;Influenza-A (H1N1)-A/PR/8/34 (TC adapted)&rsquo; and &lsquo;Human respiratory syncytial virus (hRSV) strain A2&rsquo; in a cell based in vitro setting. As eference standard, "Oseltamivir Phosphate" and "Remdesivir" were used to determine antiviral activity of test products against H1N1 and hRSV strains respectively.Results: The IC50 of ProLectin-M and ProLectin-I against SARS-CoV-2 virus was found to be 6248 ng/ml (6.2&micro;g/ml) and 4207 ng/ml (4.2&mu;g/ml) respectively. The CC50 value was similar in both the test products i.e. &gt;100 &micro;g/ml. Against Influenza A (H1N1) strain, ProLectin-M exhibited 95 % reduction in the viral load at the test concentration of 21.8 &micro;g/mL with an IC50 value of 5.4 &micro;g/mL whereas, ProLectin-I did not show any cytotoxicity till 250 &micro;g/mL concentration. Against 'human respiratory syncytial virus (hRSV) strain A2, ProLectin-M exhibited 65 % reduction in the viral load at the test concentration of 43.75 &micro;g/mL with an IC50 value of 27.41 &micro;g/mL whereas, ProLectin- I did not show any cytotoxicity till 250 &micro;g/mL concentration. Conclusion: Both ProLectin-I and ProLectin-M have been reported to exhibit broad-spectrum antiviral activity in &lsquo;in-vitro&rsquo; setting. ProLectin-M reducing influenza-A virus by 95% and hRSC strain A2 by 65%. To better understand broad spectrum antiviral activity of ProLectin-I and ProLectin-M, further pre-clinical research is warranted.