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Background: Chronic liver disease is often associated with the infection by hepatitis C virus (HCV), which is an enveloped RNA virus belonging to the Flaviviridae family. Many studies found that milk proteins, such as lactoferrin, might have profound antiviral activity against HCV. Various secretory fluids ranging from milk, to tears, saliva, and nasal secretion, and to bile and pancreatic juice, as well as neutrophils, mucosal surfaces, and blood contain a widely spread multifunctional glycoprotein, lactoferrin (Lf), structure of which can be depicted as two homologous domains connected by the short spacer peptide., Objective: This study aimed to understand the effectiveness of the synthetic peptides cLfsp, bLfsp, hLfsp1, and hLfsp2 corresponding to the spacer peptides of camel, bovine, and human Lfs, respectively, against HCV in in vitro settings., Method: We used RT-nested PCR to evaluate the antiviral activity of the synthesized spacer peptides against HCV infectivity in PBMC and HepG2 cells looking at their neutralization, protection, and intracellular treatment potentials., Results and Conclusion: We show that direct interaction of hLfsp1, hLfsp2, and bLfsp with viral particles is able to neutralize the HCV entry into HepG2 cells (with hLfsp2 being more potent neutralizer than hLfsp1 and bLfsp), whereas cLfsp does not show any neutralizing potential. Therefore, our analysis revealed that different spacer peptides are characterized by different antiviral potentials and use different mechanisms for antiviral protection., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

This article continues a series of reviews on the abundance and roles of intrinsic disorder in milk proteins. Besides caseins, which are the major proteinaceous constituents of any milk that can be isolated by isoelectric precipitation, milk contains a set of soluble whey proteins, such as β-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulins, lactoferrin, lactoperoxidase, glycomacropeptide, and proteose peptone (the last two are soluble casein derivatives). Lactoferrin and lactoperoxidase (LPO) are known to possess prominent biocidal activity, serving as efficient antibiotics and antiviral agents against a wide spectrum of bacteria, fungi, and viruses. LPO is a heme-containing peroxidase expressed as preproprotein. The mature protein has a single catalytic domain, structure of which is known for a protein isolated from several species. Functionally, LPO is a crucial component of the LPO system that includes LPO, hydrogen peroxide (H2O2), and thiocyanate (SCN(-)), being a well-studied, naturally occurring antimicrobial system in milk that is effective against many microorganisms and some viruses. Although various aspects of LPO structure and function are rather well studied and were subjects of several recent reviews, the abundance and potential functional roles of intrinsically disordered regions in this protein have never being addressed as of yet. The major goal of this article is to fill this gap and to show how intrinsic disorder is encoded in the amino acid sequence of LPO, and how intrinsic disorder is related to functions of this important milk protein.

There is no protective vaccine or effective drug against hepatitis C virus (HCV). Sustained virological response to INF/ribavirin treatment regimen has an efficiency of about 50%. Many patients worldwide have used traditional medicines and herbal medicine in particular. A laccase has been purified from oyster mushroom (Pleurotus ostreatus) to homogeneity by DEAE Affi-gel blue gel, CM-Sephadex G-50 and Sephadex G-100. The molecular weight of the laccase was about 58 kDa in SDS-PAGE. The optimum pH and temperature of the laccase activity were pH 4.0 and 60 degrees C, respectively. The activity of the enzyme increased steadily from 20 to 40 degrees C, then very slowly from 40 degrees to 60 degrees C, while the enzyme activity decreased to 9% at 90 degrees C. The activity of the laccase changed gradually over the pH range 2.0-4.0. However, the enzyme activity was totally abrogated at the pH 8 and above. Incubation of peripheral blood cells PBCs and hepatoma HepG2 cells with laccase which were then infected with HCV did not protect the cells from HCV attack and entry, while direct interaction between HCV and the laccase at the concentrations of 2.0 and 2.5 mg/ml led to a complete inhibition of virus entry after seven days of incubation. Meantime, the laccase at the concentrations of 1.0 and 1.5 mg/ml did not display any blocking activity. The potential activity of the laccase on intracellular HCV replication in infected HepG2 cells has been examined. The laccase was capable of inhibiting HCV replication at the concentrations of 1.25 and 1.5 mg/ml after first dose of treatment for four days and at the concentrations of 0.75, 1.0, 1.25 and 1.5 mg/ml after the second dose of treatment for another four days.