ImportanceNovel SARS-CoV-2 virus has infected nearly half a billion people across the world and is highly contagious. There is a need for a novel mechanism to block viral entry and stop its replication.BackgroundSpike protein N terminal domain (NTD) of the novel SARS-CoV-2 is essential for viral entry and replication in human cell. Thus the S1 NTD of human coronavirus family, which is similar to a galectin binding site - human galactose binding lectins, is a potential novel target for early treatment in COVID-19.ObjectivesTo study the feasibility of performing a definitive trial of using galectin antagonist – Prolectin-M as treatment for mild, symptomatic, rRT-PCR positive, COVID-19.Main outcomes and measuresCycle threshold (Ct) value is number of cycles needed to express fluorescence, on real time reverse transcriptase polymerase chain reaction. Ct values expressed for RNA polymerase (Rd/RP) gene +Nucleocapsid gene and the small envelope (E) genes determine infectivity of the individual. A digital droplet PCR based estimation of the Nucleocapid genes (N1+N2) in absolute copies/μL determines active viral replication.Design and interventionPilot Feasibility Randomised Controlled Open-Label, parallel arm, study. Oral tablets of Prolectin-M were administered along with the best practice, Standard of Care (SoC) and compared against SoC. Voluntarily, consenting individuals, age >18 years, and able to provide frequent nasopharyngeal and oropharyngeal swabs were randomly allocated by REDCap software.The intervention, Prolectin-M was administered as a multi dose regime of 4 gram tablets. Each tablet contained 2 grams of (1-6)-Alpha-D-mannopyranosil mixed with 2 grams of dietary fibre. Each participant took a single chewable tablet every hour, to a maximum of 10 hours in a day. Tablets were administered only during the daytime, for total of 5 days.ResultsThis pilot trial demonstrated the feasibility to recruit and randomize participants. By day 7, following treatment with Prolectin-M, Ct value of Rd/Rp + N gene increased by16.41 points, 95% (CI – 0.3527 to 32.48, p=0.047). Similarly, small envelope (E) gene also increased by 17.75 points (95% CI;-0.1321 to 35.63, p = 0.05). The expression of N1, N2 genes went below detectable thresholds by day 3 (Mann Whitney U = 0.000, p<0.029).rRT-PCR testing done in the clinic on day 1, 7, and 14 had 3 participants (60%) turn negative by day 7 and all turned negative by day 14 and stayed negative until day 28. In the SoC group 2 participants had zero detectable viral loads at baseline, 2 participants tested negative on day 14, and the last participant tested remained positive on day 28. There were no serious adverse events, and all participants were clinically asymptomatic before day 28 with reactive immunoglobulin G (IgG).Trial relevanceThis pilot study proves that it is feasible and safe to perform a trial using a Galectin antagonist in COVID-19. This is a novel mechanism for blocking viral entry and its subsequent replication.Trial RegistrationClinical Trials.gov identifier NCT04512027; CTRI ref. CTRI/2020/09/027833

The SARS-COV-2 (severe acute respiratory syndrome coronavirus 2) virus binds to human lectins to gain entry into cells to replicate. Blocking the virus’s entry using a complex polysaccharide component of [a (1-6)- D-mannopyranose termed “ProLectin M” has an effect on viral replication as a therapeutic tool and a safe alternative to existing antiviral therapies. Little is known about how galectin-3 inhibits viral entry into cells and its impact on the course of viral infection. Here, we investigated the effect of these non-cytotoxic polysaccharides on Vero cells infected with SARS-CoV-2 and demonstrated a dose-dependent reduction in viral load over a 48-hour viral incubation period. A pilot clinical study in five patients with laboratory-confirmed COVID-19 disease was treated with an oral formulation of ProLectin M, and all patients achieved complete disease remission with zero hospitalization or need for oxygen support. Moreover, the viral load was significantly lowered within 2 days of drug administration. On the viral envelope, glycans often play a crucial role in enabling pathogen transmission and/or entry into susceptible target cells. On the molecular level, our NMR spectroscopic studies show that ProLectin M binds relatively strongly to galectin-3, supporting the idea of an antagonist effect on the lectin.

The SARS-COV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) virus binds to human lectins to gain entry into cells to replicate. Blocking the virus’s entry using a complex polysaccharide component of pectin [α (1–6)- D-mannopyranose termed “ProLectin M” and Rhamnogalacturonan-II (RG-II)] that has an effect on viral replication as a therapeutic tool and a safe alternative to existing anti-viral therapies. Little is known about antagonizing galectin-3 viral-blocking activity by inhibiting viral entry into cells and subsequent viral replication, and its impact on the course of infection. Here, we investigated the effect of these non-cytotoxic polysaccharides on Vero cells infected with SARS-CoV-2 virus and demonstrated a dose-dependent reduction in viral load over a 48-hour incubation period with the virus. A pilot clinical study in five patients with laboratory-confirmed COVID-19 disease were treated with an oral formulation of α(1–6)-D-mannopyranose (ProLectin M). All patients achieved complete disease remission with zero hospitalisation or need for oxygen support. Moreover, viral load was significantly lowered within 2 days of drug administration. On the viral envelope, glycans often play a crucial role in enabling transmission of the pathogen and/or entry into its susceptible target cells. In this regard, our NMR spectroscopic studies showed on the molecular level that ProLectin M binds relatively strongly to galectin-3, supporting the idea of an antagonist effect on the lectin. Overall, our study demonstrates that blocking the viral envelope glycans can compromise entry of the virus into susceptible target cells that may translate into a positive clinical effect on the course of infection.

Background: SARS-CoV-2 vaccines play an important role in reducing disease severity, hospitalization, and death, although they failed to prevent the transmission of SARS-CoV-2 variants. Therefore, an effective inhibitor of galectin-3 (Gal-3) could be used to treat and prevent the transmission of COVID-19. ProLectin-M (PL-M), a Gal-3 antagonist, was shown to interact with Gal-3 and thereby prevent cellular entry of SARS-CoV-2 in previous studies. Aim: The present study aimed to further evaluate the therapeutic effect of PL-M tablets in 34 subjects with COVID-19. Methods: The efficacy of PL-M was evaluated in a randomized, double-blind, placebo-controlled clinical study in patients with mild to moderately severe COVID-19. Primary endpoints included changes in the absolute RT-PCR Ct values of the nucleocapsid and open reading frame (ORF) genes from baseline to days 3 and 7. The incidence of adverse events, changes in blood biochemistry, inflammatory biomarkers, and levels of antibodies against COVID-19 were also evaluated as part of the safety evaluation. Results: PL-M treatment significantly (p = 0.001) increased RT-PCR cycle counts for N and ORF genes on days 3 (Ct values 32.09 ± 2.39 and 30.69 ± 3.38, respectively) and 7 (Ct values 34.91 ± 0.39 and 34.85 ± 0.61, respectively) compared to a placebo treatment. On day 3, 14 subjects in the PL-M group had cycle counts for the N gene above the cut-off value of 29 (target cycle count 29), whereas on day 7, all subjects had cycle counts above the cut-off value. Ct values in placebo subjects were consistently less than 29, and no placebo subjects were RT-PCR-negative until day 7. Most of the symptoms disappeared completely after receiving PL-M treatment for 7 days in more patients compared to the placebo group. Conclusion: PL-M is safe and effective for clinical use in reducing viral loads and promoting rapid viral clearance in COVID-19 patients by inhibiting SARS-CoV-2 entry into cells through the inhibition of Gal-3.

Background: SARS-CoV-2 vaccines play an important role in reducing disease severity, hospitalization, and death, although they failed to prevent the transmission of SARS-CoV-2 variants. Therefore, an effective antiviral such as a Galectin-3 (Gal-3) antagonist might have the potential to prevent viral transmission. ProLectin-M (PL-M), a Gal-3 antagonist, has been shown to have anti-SARS-CoV-2 activity in previous studies. Aim: The present study aimed to further evaluate the antiviral effect of PL-M tablets in 34 subjects with COVID-19 disease, in addition to determining the antiviral mechanisms of PL-M by NMR studies. Methods: The efficacy of PL-M was evaluated in a randomized, double-blind, placebo-controlled clinical study in patients with mild to moderately severe COVID-19. Primary endpoints included changes in absolute RT-PCR Ct values of the nucleocapsid and open reading frame (ORF) genes from baseline to days 3 and 7. The incidence of adverse events, changes in blood biochemistry, inflammatory biomarkers, and levels of antibodies against COVID-19 were also evaluated as part of the safety evaluation. In vitro 1H-15N HSQC NMR spectroscopy studies were also performed to determine the interactions of PL-M with Gal-3 and the S1 spike protein of SARS-CoV-2. Results: PL-M treatment significantly (p = 0.001) increased RT-PCR cycle counts for N and ORF genes on days 3 (Ct values 32.09 and 30.69 +/- 3.38, respectively) and 7 (Ct values 34.91 +/- 0.39 and 34.85 +/- 0.61, respectively) compared to placebo. All subjects were RT-PCR negative for both genes in the PL-M treatment group from day 3 onwards. The Ct values in the placebo group were consistently less than 29 (target cycle count 29) for both genes until day 7, and no placebo subjects were negative by RT-PCR. 1H-15N HSQC NMR spectroscopy revealed that PL-M specifically binds Gal-3 in the same way as the structurally similar NTD of the SARS-CoV-2 S1 subunit. Conclusion: PL-M is safe and effective for clinical use in reducing viral load and promoting rapid viral clearance in COVID-19 patients by inhibiting SARS-CoV-2 entry into cells through inhibition of Gal-3. Keywords: Galectin-3, ProLectin-M, SARS-CoV-2, Clinical Trial, NMR, Spike protein.