A Novel Natural Influenza A H1N1 Virus Neuraminidase Inhibitory Peptide Derived from Cod Skin Hydrolysates and Its Antiviral Mechanism

Abstract

In this paper, a novel natural influenza A H1N1 virus neuraminidase (NA) inhibitory peptide derived from cod skin hydrolysates was purified and its antiviral mechanism was explored. From the hydrolysates, novel efficient NA-inhibitory peptides were purified by a sequential approach utilizing an ultrafiltration membrane (5000 Da), sephadex G-15 gel column and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequence of the pure peptide was determined by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was PGEKGPSGEAGTAGPPGTPGPQGL, with a molecular weight of 2163 Da. The analysis of the Lineweacer–Burk model indicated that the peptide was a competitive NA inhibitor with Ki of 0.29 mM and could directly bind free enzymes. In addition, docking studies suggested that hydrogen binding might be the driving force for the binding affinity of PGEKGPSGEAGTAGPPGTPGPQGL to NA. The cytopathic effect reduction assay showed that the peptide PGEKGPSGEAGTAGPPGTPGPQGL protected Madin–Darby canine kidney (MDCK) cells from viral infection and reduced the viral production in a dose-dependent manner. The EC50 value was 471 ± 12 μg/mL against H1N1. Time-course analysis showed that PGEKGPSGEAGTAGPPGTPGPQGL inhibited influenza virus in the early stage of the infectious cycle. The virus titers assay indicated that the NA-inhibitory peptide PGEKGPSGEAGTAGPPGTPGPQGL could directly affect the virus toxicity and adsorption by host cells, further proving that the peptide had an anti-viral effect with multiple target sites. The activity of NA-inhibitory peptide was almost inactivated during the simulated in vitro gastrointestinal digestion, suggesting that oral administration is not recommended. The peptide PGEKGPSGEAGTAGPPGTPGPQGL acts as a neuraminidase blocker to inhibit influenza A virus in MDCK cells. Thus, the peptide PGEKGPSGEAGTAGPPGTPGPQGL has potential utility in the treatment of the influenza virus infection.

Advances in the stability challenges of bioactive peptides and improvement strategies

“…Many peptides will be digested into inactive peptide fragments or free amino acids and lose activity in vivo after oral administration; however, these same peptides may have significant biological activity in vitro . For example, Li et al (2018) identified a novel H1N1 virus neuraminidase inhibitory peptide, PGEKGPSGEAGTAGPPGTPGPQGL, from cod skin hydrolysates, and this peptide was almost inactivated after simulated gastrointestinal digestion. Most bioactive peptide drugs, such as insulin, have to be administered by parenteral routes, which is inconvenient and painful ( Di, 2015 ).…”

Antiviral Peptides as Anti-Influenza Agents

“…Moreover, time-course analysis showed that it inhibited Influenza virus in the early stage of the infectious cycle. Unfortunately, it was observed that the activity of the peptide was inactivated during the simulated in vitro gastrointestinal digestion, suggesting that oral administration was not recommended [ 152 ]. Recently, Chen et al identified an octapeptide, errKPAQP (P2), from a small library of 20 peptides, designed from the binding pocket of oseltamivir in neuraminidase.…”

Comprehensive overview of COVID ‐19 based on current evidence

“…HA proteins are used to bind to sialic acids and then genetic material penetrates into the target cell through the material transport channel, combines with the DNA and finally many progeny viruses are formed 10‐13 . NA is responsible for catalyzing the hydrolysis of glycoside bond so that the mature virus particles eventually leave the host cells and infect new epithelial cells 14‐18 . Compared with coronavirus, S protein exists in the form of homologous trimer and its monomer can be recognized by protease.…”