Structural and functional modeling of human lysozyme reveals a unique nonapeptide, HL9, with anti-HIV activity

Uncovering the antimicrobial activity of G-type lysozyme 2 derived from Cyprinus carpio mucus against bacterial and fungal pathogens

This study aimed to explore the antimicrobic potential of mucus samples collected from Cyprinus carpio and identify the specific antimicrobial peptides responsible for its activity. The crude extract was tested against various bacterial and fungal pathogens, and its protein content and profile were analyzed. Purification steps, including gel filtration chromatography, were employed to isolate the most active fraction (peak IV), which was further identified via liquid chromatography and mass spectroscopy. The results revealed varying degrees of antimicrobial activity of the crude extract against different bacterial and fungal strains, with Leclercia adecarboxylata, Candida glabrata, and Candida parapsilosis showing the highest susceptibility. SDS-PAGE analysis demonstrated the existence of multiple low molecular weight protein bands in the crude extract, while fraction IV obtained from gel filtration chromatography exhibited the strongest antimicrobial activity. Peak IV displayed a range of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) values against the tested pathogens, spanning from 0.038 to 4.960 mg/mL. Further investigation identified the purified peptide derived from peak IV as G-type lysozyme 2, characterized by a molecular weight of 21 kDa. These findings shed light on the existence of a highly effective antimicrobial peptide, G-type lysozyme 2, within the mucus of Cyprinus carpio. This peptide demonstrates notable activity against diverse bacterial and fungal pathogens. The insights from this study enhance our understanding of the fish's antimicrobial defense mechanisms and hold promise for developing novel antimicrobial agents.

Lysozyme: A Natural Product with Multiple and Useful Antiviral Properties

Lysozyme, especially the one obtained from hen's egg white, continues to show new pharmacological properties. The fact that only a few of these properties can be translated into therapeutic applications is due to the lack of suitable clinical studies. However, this lack cannot hide the evidence that is emerging from scientific research. This review for the first time examines, from a pharmacological point of view, all the relevant studies on the antiviral properties of lysozyme, analyzing its possible mechanism of action and its ability to block viral infections and, in some cases, inhibit viral replication. Lysozyme can interact with nucleic acids and alter their function, but this effect is uncoupled from the catalytic activity that determines its antibacterial activity; it is present in intact lysozyme but is equally potent in a heat-degraded lysozyme or in a nonapeptide isolated by proteolytic digestion. An analysis of the literature shows that lysozyme can be used both as a disinfectant for raw and processed foods and as a drug to combat viral infections in animals and humans. To summarize, it can be said that lysozyme has important antiviral properties, as already suspected in the initial studies conducted over 50 years ago, and it should be explored in suitable clinical studies on humans.

Pharmacological Modulation of Host Immunity with Hen Egg White Lysozyme (HEWL)-A Review

In the 100 years since its discovery, lysozyme has become an important molecule, both as model for studies in different fields and as a candidate for the therapy of various pathological conditions. Of the dozens of known lysozymes, in this review we focus on one in particular, lysozyme extracted from hen egg white (HEWL), and its interaction with the immune system when it is administered orally. Experimental data show that there is an axis that directs immune system activation from GALT (gut-associated lymphoid tissue) and the intestinal lymphocyte clusters. Although a contribution of peptidoglycans from digestion of the bacterial cell wall in the intestinal lumen cannot be excluded, immune stimulation is not dependent on the enzymatic activity of HEWL. The immune responses suggest that HEWL is able to recover from immunodepression caused by tumor growth or immunosuppressants, and that it also improves the success of chemotherapy. The positive results obtained in a small Phase 2 study in patients, the ease of oral administration of this protein, and the absence of adverse effects suggest that HEWL may play an important role in all diseases where the immune system is weakened or where its enhancement plays a critical role in the resolution of the pathology.

Deciphering the molecular details of interactions between anti-COVID drugs and functional human proteins: in silico approach

The molecular docking calculations have been employed to investigate the interactions a set of proteins with the repurposed anti-COVID drugs. The position of the therapeutic agents within the protein structure was dependent on a particular drug-protein system and varied from the binding cleft to the periphery of the polypeptide chain. Interactions involved in the drug-protein complexation includes predominantly hydrogen bonding and hydrophobic contacts. The obtained results may be of particular importance while developing the anti-COVID strategies as well as for deeper understanding of the drug pharmacodynamics and pharmacokinetics.

In vitro PCR verification that lysozyme inhibits nucleic acid replication and transcription

Lysozyme can kill bacteria by its enzymatic activity or through a mechanism involving its cationic nature, which can facilitate electrostatic interactions with the viral capsid, the negatively charged parts of nucleic acids, and polymerase, so binding to nucleic acids may be another biological function of lysozyme. Here, PCR was used as a research tool to detect the effects of lysozyme on the replication and transcription of nucleic acids after treatment in different ways. We found that lysozyme and its hydrolysate can enter cells and inhibit PCR to varying degrees in vitro, and degraded lysozyme inhibited nucleic acid replication more effectively than intact lysozyme. The inhibition of lysozyme may be related to polymerase binding, and the sensitivity of different polymerases to lysozyme is inconsistent. Our findings provide a theoretical basis for further explaining the pharmacological effects of lysozyme, such as antibacterial, antiviral, anticancer, and immune regulatory activities, and directions for the development of new pharmacological effects of lysozyme and its metabolites.

Stabilization of Labile Lysozyme-Ligand Interactions in Native Electrospray Ionization Mass Spectrometry

Flavonoids are polyphenolic secondary metabolites with extensive biological activities and pharmacological effects. Exploring the interactions of flavonoids with proteins may be helpful for understanding their biological processes. Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool to characterize the noncovalent protein-ligand (PL) complexes. However, some protein-flavonoid complexes are labile during electrospray ionization. Here, the labile lysozyme-flavonoid (rutin, icariin, and naringin) complexes were determined by direct ESI-MS without derivation. It has been found that low amounts of N-methylpyrrolidinone and dimethylformamide can protect labile lysozyme-flavonoid complexes away from dissociation during electrospray ionization process. The intact lysozyme-flavonoid complexes were specifically observed in mass spectra, and the measured binding affinities by ESI-MS were matched with the fluorescence data. The effects of additives on the analysis of lysozyme-flavonoid complexes were investigated by ESI-MS, combined with the molecular docking and fluorescence. This strategy was helpful to investigate the labile PL interactions by direct ESI-MS.

Molecular characterization and antibacterial activities of a goose-type lysozyme gene from roughskin sculpin (Trachidermus fasciatus)

Lysozymes, acting as antimicrobial molecules, play a vital role in the host's innate immune response to pathogen infections. In the present study, a g-type lysozyme gene termed Tf-LyzG from roughskin sculpin, Trachidermus fasciatus was firstly reported. The deduced amino acid sequence of Tf-LyzG contained 188 residues and possessed conserved catalytic residues (Glu⁷¹, Asp⁸⁴, and Asp⁹⁵). Gene expression analysis revealed that Tf-LyzG was widely distributed in the tested eleven tissues with the highest expression in the gill and could be significantly induced post lipopolysaccharide (LPS) challenge. The lysozyme activity of the purified recombinant protein (rTf-LyzG) was found to be most active at pH 5.5 and 37 °C. rTf-LyzG exhibited a wide spectrum of potent bacteriolytic activity against four Gram-positive bacteria and six Gram-negative bacteria. It also displayed a high affinity to polysaccharides on bacteria surfaces including LPS, lipoteichoic acid (LTA), and peptidoglycan (PGN). rTf-LyzG was capable of binding and agglutinating all nine bacteria. Flow cytometry assay further revealed that rTf-LyzG could disrupt the membrane of Micrococcus lysodeikticus which is confirmed by scanning electron microscope (SEM) analysis that reveals blebs around the bacterial cell membrane. In summary, these data indicate that Tf-LyzG is of great importance in the fish immune response against pathogens invasion.

The Influence of Proteins on Fate and Biological Role of Circulating DNA

Circulating DNA has already proven itself as a valuable tool in translational medicine. However, one of the overlooked areas of circulating DNA research is its association with different proteins, despite considerable evidence that this association might impact DNA's fate in circulation and its biological role. In this review, we attempt to shed light on current ideas about circulating DNA origins and forms of circulation, known biological effects, and the clinical potential of circulating tumor deoxyribonucleoprotein complexes.

Crystal Structure of Human Lysozyme Complexed with N-Acetyl-α-d-glucosamine

Human lysozyme is a natural non-specific immune protein that participates in the immune response of infants against bacterial and viral infections. Lysozyme is a well-known hydrolase that cleaves peptidoglycan in bacterial cell walls. Several crystal structures of human lysozyme have been reported, but little is known regarding how it recognizes sugar molecules. In this study, the crystal structures of human lysozyme in its native and two N-acetyl-α-d-glucosamine (α-D-NAG)-bound forms were determined at 1.3 Å and 1.55/1.60 Å resolution, respectively. Human lysozyme formed a typical c-type lysozyme fold and the α-D-NAG molecule was bound to the middle of subsites C and D. The N-acetyl and glucosamine groups of α-D-NAG were stabilized by hydrophobic interactions (Val117, Ala126, and Trp127), hydrogen bonds (Asn64, Asn78, Ala126, and Val128), and water bridges. Conformational changes of Arg80, Tyr81, Val128, and Arg131 of human lysozyme were observed due to the interactions of α-D-NAG with the active-site cleft. The binding configuration of α-D-NAG in human lysozyme was distinct compared with that of other sugar-bound lysozymes. Findings from this structural analysis provide a better understanding of the sugar recognition of human lysozyme during the immune response to microbial pathogens.

Recent Insights Into the Prognostic and Therapeutic Applications of Lysozymes

Lysozymes are naturally occurring enzymes present in a variety of biological organisms, such as bacteria, fungi, and animal bodily secretions and tissues. It is also the main ingredient of many ethnomedicines. It is well known that lysozymes and lysozyme-like enzymes can be used as anti-bacterial agents by degrading bacterial cell wall peptidoglycan that leads to cell death, and can also inhibit fungi, yeasts, and viruses. In addition to its direct antimicrobial activity, lysozyme is also an important component of the innate immune system in most mammals. Increasing evidence has shown the immune-modulatory effects of lysozymes against infection and inflammation. More recently, studies have revealed the anti-cancer activities of lysozyme in multiple types of tumors, potentially through its immune-modulatory activities. In this review, we summarized the major functions and underlying mechanisms of lysozymes derived from animal and plant sources. We highlighted the therapeutic applications and recent advances of lysozymes in cancers, hypertension, and viral diseases, aiming toseeking alternative therapies for standard medical treatment bypassing side effects. We also evaluated the role of lysozyme as a promising cancer marker for prognosis to indicate the outcomes recurrence for patients.

Early antiretroviral therapy initiation effect on metabolic profile in vertically HIV-1-infected children

BACKGROUND

Early combined antiretroviral treatment (cART) in perinatally acquired HIV-1 children has been associated with a rapid viral suppression, small HIV-1 reservoir size and reduced mortality and morbidity. Immunometabolism has emerged as an important field in HIV-1 infection offering both relevant knowledge regarding immunopathogenesis and potential targets for therapies against HIV-1.

OBJECTIVES

To characterize the proteomic, lipidomic and metabolomic profile of HIV-1-infected children depending on their age at cART initiation.

PATIENTS AND METHODS

Plasma samples from perinatally HIV-1-infected children under suppressive cART who initiated an early cART (first 12 weeks after birth, EARLY, n = 10) and late cART (12-50 weeks after birth, LATE, n = 10) were analysed. Comparative plasma proteomics, lipidomics and metabolomics analyses were performed by nanoLC-Orbitrap, UHPLC-qTOF and GC-qTOF, respectively.

RESULTS

Seven of the 188 proteins identified exhibited differences comparing EARLY and LATE groups of HIV-1-infected children. Despite no differences in the lipidomic (n = 115) and metabolomic (n = 81) profiles, strong correlations were found between proteins and lipid levels as well as metabolites, including glucidic components and amino acids, with clinical parameters. The ratio among different proteins showed high discriminatory power of EARLY and LATE groups.

CONCLUSIONS

Protein signature show a different proinflammatory state associated with a late cART introduction. Its associations with lipid levels and the relationships found between metabolites and clinical parameters may potentially trigger premature non-AIDS events in this HIV-1 population, including atherosclerotic diseases and metabolic disorders. Antiretroviral treatment should be started as soon as possible in perinatally acquired HIV-1-infected children to prevent them from future long-life complications.

Antiviral Properties of Human Milk

Humans have always coexisted with viruses, with both positive and negative consequences. Evolutionary pressure on mammals has selected intrinsic properties of lactation and milk to support the relatively immunocompromised neonate from environmental pathogens, as well as support the normal development of diverse immune responses. Human milk supports both adaptive and innate immunity, with specific constituents that drive immune learning and maturation, and direct protection against microorganisms. Viruses constitute one of the most ancient pressures on human evolution, and yet there is a lack of awareness by both public and healthcare professionals of the complexity of human milk as an adaptive response beyond the production of maternal antibodies. This review identifies and describes the specific antiviral properties of human milk and describes how maternal support of infants through lactation is protective beyond antibodies.

Development and evaluation of inhalable composite niclosamide-lysozyme particles: A broad-spectrum, patient-adaptable treatment for coronavirus infections and sequalae

Niclosamide (NIC) has demonstrated promising in vitro antiviral efficacy against SARS-CoV-2, the causative agent of the COVID-19 pandemic. Though NIC is already FDA-approved, administration of the currently available oral formulation results in systemic drug levels that are too low for the inhibition of SARS-CoV-2. We hypothesized that the co-formulation of NIC with an endogenous protein, human lysozyme (hLYS), could enable the direct aerosol delivery of the drug to the respiratory tract as an alternative to oral delivery, thereby effectively treating COVID-19 by targeting the primary site of SARS-CoV-2 acquisition and spread. To test this hypothesis, we engineered and optimized composite particles containing NIC and hLYS suitable for delivery to the upper and lower airways via dry powder inhaler, nebulizer, and nasal spray. The novel formulation demonstrates potent in vitro and in vivo activity against two coronavirus strains, MERS-CoV and SARS-CoV-2, and may offer protection against methicillin-resistance staphylococcus aureus pneumonia and inflammatory lung damage occurring secondary to SARS-CoV-2 infections. The suitability of the formulation for all stages of the disease and low-cost development approach will ensure rapid clinical development and wide-spread utilization.

Production of an invertebrate lysozyme of Scylla paramamosain in E.coli and evaluation of its antibacterial, antioxidant and anti-inflammatory effects

Lysozymes, which are secreted in many organisms, including invertebrates, mammals, plants, bacteria and fungus, exhibit antimicrobial, antiviral, antioxidant, and anti-inflammatory activities. Splys-i is an invertebrate-type (i-type) lysozyme isolated from Scylla paramamosain in 2017 and is involved in immune defense against bacteria. However, the antibacterial, antioxidant, and anti-inflammatory activities of Splys-i remain to be elucidated. In the current study, the expression parameters (including IPTG concentration, induction temperature, and induction duration) of Splys-i in Escherichia coli were optimized to achieve high-level yield through shake-flask cultivation with approximately 120 mg of Splys-i obtained from 1 L of LB medium. The purified Splys-i displayed low cytotoxicity to RAW264.7 macrophage cells and low hemolytic activity against erythrocytes of mouse, rat, and rabbit, respectively, and exhibited potent antibacterial activity against both Gram-positive and -negative bacteria with minimum concentrations ranging from 15 to 90 μg/mL. The antibacterial property of Splys-i was also unaffected when treated with various temperature, pHs, and salinity, respectively, and Splys-i showed resistance to proteinase digestion. Radical-scavenging rate assay (including ABTS⁺, DPPH, hydroyl free radical, and superoxide anion) indicated that Splys-i was an efficient antioxidant. Splys-i also exerted anti-inflammatory effect through the inhibition of IκBα and NF-κB(P65) phosphorylation, thereby reducing the secretion of pro-inflammatory cytokines. All these results suggested that Splys-i can be prepared from E. coli with potent biological property.

The potential of lactoferrin, ovotransferrin and lysozyme as antiviral and immune-modulating agents in COVID-19

Coronavirus disease 2019 (COVID-19), caused by SARS coronavirus 2 (SARS-CoV-2), is spreading rapidly with no established effective treatments. While most cases are mild, others experience uncontrolled inflammatory responses with oxidative stress, dysregulation of iron and coagulation as features. Lactoferrin, ovotransferrin and lysozyme are abundant, safe antimicrobials that have wide antiviral as well as immunomodulatory properties. In particular, lactoferrin restores iron homeostasis and inhibits replication of SARS-CoV, which is closely related to SARS-CoV-2. Ovotransferrin has antiviral peptides and activities that are shared with lactoferrin. Both lactoferrin and lysozyme are ‘immune sensing’ as they may stimulate immune responses or resolve inflammation. Mechanisms by which these antimicrobials may treat or prevent COVID-19, as well as sources and forms of these, are reviewed.

Synthesis and Characterization of Selenium Nanoparticles-Lysozyme Nanohybrid System with Synergistic Antibacterial Properties

In the light of promising potency of selenium nanoparticles in biomedical applications, this is the first study to report the synergistic antibacterial activity of these nanoparticles and lysozyme. The nanohybrid system was prepared with various concentrations of each component. Resistance of Escherichia coli and Staphylococcus aureus was compared in the presence of individual Nano and Bio counterparts as well as the nanohybrid system. Upon interaction of SeNPs with Lysozyme, the nanohybrid system efficiently enhanced the antibacterial activity compared to the protein. Therefore, SeNPs play an important role in inhibition of bacterial growth at very low concentrations of protein; whereas very high amount of the protein is required to inhibit bacterial growth individually. On the other hand, lysozyme has also played a vital role in antibacterial property of SeNPs, inducing 100% inhibition at very low concentration of each component. Hence, presence of both nano and bio counterparts induced vital interplay in the Nanohybrid system. The aged samples also presented good stability of SeNPs both as the intact and complex form. Results of this effort highlight design of nanohybrid systems with synergistic antibacterial properties to overcome the emerging antibiotic resistance as well as to define fruitful applications in biomedicine and food safety.

Discovery of High Abundances of Aster-Like Nanoparticles in Pelagic Environments: Characterization and Dynamics

This study reports the discovery of Aster-Like Nanoparticles (ALNs) in pelagic environments. ALNs are pleomorphic, with three dominant morphotypes which do not fit into any previously defined environmental entities [i.e., ultramicro-prokaryotes, controversed nanobes, and non-living particles (biomimetic mineralo-organic particles, natural nanoparticles or viruses)] of similar size. Elemental composition and selected-area electron diffraction patterns suggested that the organic nature of ALNs may prevail over the possibility of crystal structures. Likewise, recorded changes in ALN numbers in the absence of cells are at odds with an affiliation to until now described viral particles. ALN abundances showed marked seasonal dynamics in the lakewater, with maximal values (up to 9.0 ± 0.5 × 10⁷ particles·mL⁻¹) reaching eight times those obtained for prokaryotes, and representing up to about 40% of the abundances of virus-like particles. We conclude that (i) aquatic ecosystems are reservoirs of novel, abundant, and dynamic aster-like nanoparticles, (ii) not all virus-like particles observed in aquatic systems are necessarily viruses, and (iii) there may be several types of other ultra-small particles in natural waters that are currently unknown but potentially ecologically important.

Multi-spectroscopic and molecular dynamics simulations investigation of the binding mechanism of polybrominated diphenyl ethers to hen egg white lysozyme

Three PBDEs (BDE25, BDE47, and BDE154) were selected to investigate the interactions between PBDEs and hen egg white lysozyme (HEWL) by molecular modeling, fluorescence spectroscopy, and FT-IR spectra. The docking results showed that hydrogen bonds were formed between BDE25 and residue TRP63 and between BDE47 and TRP63 with bond lengths of 2.178 Å and 2.146 Å, respectively. The molecular dynamics simulations indicated that van der Waals forces played a predominant role in the binding of three PBDEs to HEWL. The observed fluorescence quenching can be attributed to the formation of complexes between HEWL and PBDEs, and the quenching mechanism is a static quenching. According to Förster's non-radiative energy transfer theory, the binding distances r were < 7 nm, indicating a high probability of energy transfer from HEWL to the three PBDEs. The synchronous fluorescence showed that the emission maximum wavelength of tryptophan (TRP) residues emerged a red-shift. FT-IR spectra indicated that BDE25, BDE47 and BDE154 induced the α-helix percentage of HEWL decreased from 32.70% ± 1.64% to 28.27% ± 1.41%, 27.50% ± 1.38% and 29.78% ± 1.49%, respectively, whereas the percentage of random coil increased from 26.67% ± 1.33% to 27.60% ± 1.38%, 29.18% ± 1.46% and 30.59% ± 1.53%, respectively.

A balanced game: chicken macrophage response to ALV-J infection

Avian leukosis virus subgroup J (ALV-J) infection can cause tumors and immunosuppression in infected chickens. Macrophages play a central role in host defense against invading pathogens. In this study, we discovered an interesting phenomenon: ALV-J replication is weakened from 3 hours post-infection (hpi) to 36 hpi, which was verified using Western blotting and RT-PCR. To further investigate the interaction between ALV-J and macrophages, transcriptome analysis was performed to analyze the host genes’ function in chicken primary monocyte-derived macrophages (MDM). Compared to the uninfected control, 624 up-regulated differentially expressed genes (DEG) and 341 down-regulated DEG at 3 hpi, and 174 up-regulated DEG and 87 down-regulated DEG at 36 hpi were identified in chicken MDM, respectively. ALV-J infection induced strong innate immune responses in chicken MDM at 3 hpi, instead of 36 hpi, according to the analysis results of Gene Ontology and KEGG pathway. Importantly, the host factors, such as up-regulated MIP-3α, IL-1β, iNOS, K60, IRG1, CH25H, NFKBIZ, lysozyme and OASL were involved in the host defense response during the course of ALV-J infection. On the contrary, up-regulated EX-FABP, IL4I1, COX-2, NFKBIA, TNFAIP3 and the Jak STAT pathway inhibitors including CISH, SOCS1 and SOCS3 are beneficial to ALV-J survival in chicken macrophages. We speculated that ALV-J tropism for macrophages helps to establish a latent infection in chicken MDM from 6 to 36 hpi. The present study provides a comprehensive view of the interactions between macrophages and ALV-J. It suggests the mechanisms of defense of chicken macrophages against ALV-J invasion and how ALV-J escape the host innate immune responses.

A facile electrochemical aptasensor for lysozyme detection based on target-induced turn-off of photosensitization

The quantification of proteins is essential in fundamental research or clinical applications. Here, we developed a facile electrochemical aptasensor based on target-induced turn-off of photosensitization for label-free and ultrasensitive detection of protein (exemplified by lysozyme). EB (ethidium bromide) molecules that were embedded in dsDNA between lysozyme binding aptamer and complementary DNA immobilized on the electrode, could photo-cleave the dsDNA via singlet oxygen (O₂¹) during photosensitization, resulting in a high voltammetry current of the [Fe(CN)₆]^3-/4-. Upon recognition of the lysozyme by aptamer, the EB molecules were released from dsDNA, and its photosensitization activity was turned off. As a result, more amount of complementary DNA was retained on the Au nanoparticles modified carbon nanotube paste electrode (AuNPs-CNPE), leading to a declined voltammetry current. Such a sensing strategy allowed detection of 10 pM-1 µM lysozyme with a low detection limit (about 2 pM). Besides, the sensor was free of labeling procedure as well as extra signal amplification step, and the CNPE modification was quite simple, only with AuNPs. The sensor also showed excellent selectivity toward lysozyme in the presence of interfering proteins, such as thrombin, bovine serum albumin, myoglobin, etc. The proposed sensor was applied to the determination of lysozyme in urine samples with the recoveries ranging from 96.6% to 101%. The proposed biosensor holds a great promise in developing other electrochemical sensors based on photosensitization.

C-lysozyme contributes to antiviral immunity in Bombyx mori against nucleopolyhedrovirus infection

Lysozymes is a ubiquitous immune effector that is widely distributed in both vertebrates and invertebrates. Previous reports have shown that lysozymes significantly inhibit viral infections in vertebrates. However, the antiviral effects of lysozymes in invertebrates remain unclear. Here, we investigated the role of lysozymes in Bombyx mori (B. mori) response to viral infection by overexpressing B. mori C-lysozyme (BmC-LZM) in larvae and cells. We found that BmC-LZM was up-regulated in cells in response to viral infection. Indeed, the overexpressing of BmC-LZM significantly inhibited viral replication in cells during late-stage infection. However, this effect was reversed by BmC-LZM mRNA. BmC-LZM was successfully overexpressed in B. mori strain 871 using Baculovirus Expression Vector System (BEVS). This overexpression markedly reduced viral proliferation and increased larval survival percentage. Thus, BmC-LZM inhibited viral replication both in vivo and in vitro, indicating that BmC-LZM is involved in the insect immune response to viral infection. Our results provide a basis for further applications of lysozymes.

Lysozyme's lectin-like characteristics facilitates its immune defense function

Interactions between human lysozyme (HL) and the lipopolysaccharide (LPS) of Klebsiella pneumoniae O1, a causative agent of lung infection, were identified by surface plasmon resonance. To characterize the molecular mechanism of this interaction, HL binding to synthetic disaccharides and tetrasaccharides representing one and two repeating units, respectively, of the O-chain of this LPS were studied. pH-dependent structural rearrangements of HL after interaction with the disaccharide were observed through nuclear magnetic resonance. The crystal structure of the HL-tetrasaccharide complex revealed carbohydrate chain packing into the A, B, C, and D binding sites of HL, which primarily occurred through residue-specific, direct or water-mediated hydrogen bonds and hydrophobic contacts. Overall, these results support a crucial role of the Glu35/Asp53/Trp63/Asp102 residues in HL binding to the tetrasaccharide. These observations suggest an unknown glycan-guided mechanism that underlies recognition of the bacterial cell wall by lysozyme and may complement the HL immune defense function.

Dextran-Conjugated Lysozymes Inhibit the Growth of Shigella sonnei and Viral Hemorrhagic Septicemia Virus

Lysozyme is well known as a natural antimicrobial agent, but its function is limited in that it only combats Gram-positive bacteria. We investigated the inhibitory effects of dextran-conjugated lysozymes (DLs) against some strains of Gram-negative bacteria and viral hemorrhagic septicemia virus (VHSV). The Maillard reactions of the DL were performed at various pHs (3.0, 7.0, and 8.5) in the presence of saturated KBr solution for 1, 3, 5, 7, and 9 days. The growth inhibition effects against Gram-negative bacterial strains, such as Escherichia coli, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Shigella sonnei, and Shigella flexneri were found only in some DLs. DLs incubated at pH 7.0 for 9 days strongly inhibited growth of S. sonnei (92.9%). Fathead minnow (FHM) cells were infected with VHSV. DLs treated at all pHs for 1 day resulted in more than 80% viability of VHSV-infected FHM cells. The results of this study suggest that our DLs can be useful in food preservatives, pharmaceuticals, or aquatic feed due to their inhibitory effects against pathogenic bacteria and viral infections.

Binding of naringin and naringenin with hen egg white lysozyme: A spectroscopic investigation and molecular docking study

The interactions of naringenin (NG) and naringin (NR) with Hen Egg White Lysozyme (HEWL) in aqueous medium have been investigated using UV-vis spectroscopy, steady-state fluorescence, circular dichroism (CD), Fourier Transform infrared spectroscopy (FT-IR) and molecular docking analyses. Both NG and NR can quench the intrinsic fluorescence of HEWL via static quenching mechanism. At 300K, the value of binding constant (K_b) of HEWL-NG complex (5.596±0.063×10⁴M^-1) was found to be greater than that of HEWL-NR complex (3.404±0.407×10⁴M^-1). The negative ΔG° values in cases of both the complexes specify the spontaneous binding. The binding distance between the donor (HEWL) and acceptor (NG/NR) was estimated using the Försters theory and the possibility of non-radiative energy transfer from HEWL to NG/NR was observed. The presence of metal ions (Ca²⁺, Cu²⁺ and Fe²⁺) decreased the binding affinity of NG/NR towards HEWL. Synchronous fluorescence studies indicate the change in Trp micro-environment due to the incorporation of NG/NR into HEWL. CD and FT-IR studies indicated that the α-helicity of the HEWL was slightly enhanced due to ligand binding. NG and NR inhibited the enzymatic activity of HEWL and exhibited their affinity for the active site of HEWL. Molecular docking studies revealed that both NG and NR bind in the close vicinity of Trp 62 and Trp 63 residues which is vital for the catalytic activity.

Ru(bpy)32+-Silica@Poly-L-lysine-Au as labels for electrochemiluminescence lysozyme aptasensor based on 3D graphene

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)₃²⁺-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)₃²⁺-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10^-12 to 5.0 × 10^-8 mol L^-1, and the detection limit was estimated to 7.5 × 10^-13 mol L^-1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.

Inhibition of Human Immunodeficiency Type 1 Virus (HIV-1) Life Cycle by Different Egg White Lysozymes

Lysozyme is a relatively small enzyme with different biological activities, which is found in tears, saliva, egg white, and human milk. In the study, the anti-HIV-1 activity of lysozymes purified from quail, Meleagris, and hen egg white has been determined. For this end, a time-of-drug-addition assay was performed to identify the target of anti-HIV-1 agents and for determination of probable anti HIV-1 mechanism of the studied lysozyme, the binding affinity of the lysozymes to the human CD4 receptor was studied by molecular docking method. To define structural differences between studied lysozymes, structural motifs of them were predicted by MEME tool. Quail, hen, and Meleagris lysozymes showed potent anti-HIV-1 activity with EC₅₀ of 7.5, 10, and 55 nM, respectively. The time-of-drug-addition study demonstrated that the inhibitory effect of all purified lysozymes is before HIV-1 infection. The frequency and intensity of CD4 expression in PBMCs decreased in the presence of all mentioned lysozymes. Also, the expression level of C-C chemokine receptor type 5 (CCR5) and chemokine receptor type 4 (CXCR4) on CD4+ T cells was not changed in cells treated with these lysozymes. The results of in silico study confirmed that the binding energy of quail lysozyme with CD4 was more than that of other studied lysozymes. The results revealed that these lysozymes restrict HIV-1 attachment to host cell CD4.

HIV-Enhancing and HIV-Inhibiting Properties of Cationic Peptides and Proteins

Cationic antimicrobial peptides and proteins have historically been ascribed roles in innate immunity that infer killing of microbial and viral pathogens and protection of the host. In the context of sexually transmitted HIV-1, we take an unconventional approach that questions this paradigm. It is becoming increasingly apparent that many of the cationic polypeptides present in the human genital or anorectal mucosa, or human semen, are capable of enhancing HIV-1 infection, often in addition to other reported roles as viral inhibitors. We explore how the in vivo environment may select for or against the HIV-enhancing aspects of these cationic polypeptides by focusing on biological relevance. We stress that the distinction between enhancing and inhibiting HIV-1 infection is not mutually exclusive to specific classes of cationic polypeptides. Understanding how virally enhancing peptides and proteins act to promote sexual transmission of HIV-1 would be important for the design of topical microbicides, mucosal vaccines, and other preventative measures.

Structural and functional analysis of lysozyme after treatment with dielectric barrier discharge plasma and atmospheric pressure plasma jet

The variation in the biological function of proteins plays an important role in plasma medicine and sterilization. Several non-thermal plasma sources with different feeding gases are used worldwide for plasma treatment, including dielectric barrier discharge (DBD) and atmospheric-pressure plasma jet (APPJ) as the most commonly used sources. Therefore, in the present work, we used both DBD and APPJ plasma sources with N2 and air as feeding gases to evaluate the effects on the structural, thermodynamic, and activity changes of enzymes. In the current work, we used lysozyme as a model enzyme and verified the structural changes using circular dichroism (CD), fluorescence, and X-ray crystallography. In addition, we investigated the lysozyme thermodynamics using CD thermal analysis and changes in the B-factor from X-ray crystallography. The results showed that lysozyme activity decreased after the plasma treatment. From these analyses, we concluded that N2-feeding gas plasma disturbs the structure and activity of lysozyme more than Air feeding gas plasma in our experimental studies. This study provides novel fundamental information on the changes to enzymes upon plasma treatment, which has been absent from the literature until now.

Human Antimicrobial Peptides in Bodily Fluids: Current Knowledge and Therapeutic Perspectives in the Postantibiotic Era

Antimicrobial peptides (AMPs) are an integral part of the innate immune defense mechanism of many organisms. Due to the alarming increase of resistance to antimicrobial therapeutics, a growing interest in alternative antimicrobial agents has led to the exploitation of AMPs, both synthetic and isolated from natural sources. Thus, many peptide-based drugs have been the focus of increasing attention by many researchers not only in identifying novel AMPs, but in defining mechanisms of antimicrobial peptide activity as well. Herein, we review the available strategies for the identification of AMPs in human body fluids and their mechanism(s) of action. In addition, an overview of the distribution of AMPs across different human body fluids is provided, as well as its relation with microorganisms and infectious conditions.

Molecular characterization, transcriptional profiling, and antibacterial potential of G-type lysozyme from seahorse (Hippocampus abdominalis)

Lysozymes are a family of enzymes that catalyze the hydrolysis of bacterial cell wall, acting as antimicrobial effectors of the innate immune system. In the present study, an ortholog of goose-type lysozyme (ShLysG) from the big-belly seahorse (Hippocampus abdominalis) was identified and characterized structurally and functionally. The full-length cDNA sequence (1213 bp) of ShLysG is comprised of an open reading frame made up of 552 bp, encoding a polypeptide of 184 amino acid (aa) with a predicted molecular mass of 20 kDa. In silico analysis of ShLysG revealed the absence of signal peptide and the presence of a characteristic bacterial soluble lytic transglycosylase (SLT) domain bearing three catalytic residues (Glu⁷¹, Asp⁸⁴, and Asp⁹⁵) and seven N-acetyl-d-glucosamine binding sites (Glu⁷¹, Asp⁹⁵, Tyr⁹⁸, His⁹⁹, Ile¹¹⁷, Tyr¹⁴⁵, and Asn¹⁴⁶). Homology analysis demonstrated that the aa sequence of ShLysG shared 60.7-67.4% identity and 72.6-79.3% similarity with the orthologs of other teleosts. Phylogenetic analysis of ShLysG indicated a closest relationship with the ortholog from Gadus morhua. In healthy seahorse, ShLysG mRNA showed a constitutive expression in all the tissues examined, with the highest expression in kidney and the least expression in liver. The ShLysG mRNA levels were also shown significant elevation upon the bacterial and pathogen-associated molecular pattern (PAMPs) challenges. Furthermore, lytic activities of ShLysG recombinant protein were detected against several Gram-negative and Gram-positive bacterial species. Taken together, these results suggest that ShLysG might possess a potential immune defensive role against invading microbial pathogens in seahorse.

Interfacial and Wetting Behavior of Cationic, Anionic and Nonionic Surfactants in the Absence and Presence of Lysozyme

Herein, we discuss various physicochemical properties of cationic (CTAB), anionic (SDBS) and nonionic (TX-100) surfactants in the presence and absence of lysozyme, at different temperatures by using tensiometery. The surface excess (Γmax) decreases with the increase in temperature for all three kinds of surfactants in the presence and absence of lysozyme, but the most prominent decrease is to be observed for SDBS as compared to CTAB and TX-100 in the presence of lysozyme. The minimum area per molecule (Amin) follows the opposite trend as expected. In addition, contact angle analysis was also done to observe the wettability of poly(methyl methacrylate) (PMMA) surface by these surfactants in the presence and absence of lysozyme.

Breast Milk and Solid Food Shaping Intestinal Immunity

After birth, the intestinal immune system enters a critical developmental stage, in which tolerogenic and pro-inflammatory cells emerge to contribute to the overall health of the host. The neonatal health is continuously challenged by microbial colonization and food intake, first in the form of breast milk or formula and later in the form of solid food. The microbiota and dietary compounds shape the newborn immune system, which acquires the ability to induce tolerance against innocuous antigens or induce pro-inflammatory immune responses against pathogens. Disruption of these homeostatic mechanisms might lead to undesired immune reactions, such as food allergies and inflammatory bowel disease. Hence, a proper education and maturation of the intestinal immune system is likely important to maintain life-long intestinal homeostasis. In this review, the most recent literature regarding the effects of dietary compounds in the development of the intestinal immune system are discussed.

Antiviral activities of whey proteins

Milk contains an array of proteins with useful bioactivities. Many milk proteins encompassing native or chemically modified casein, lactoferrin, alpha-lactalbumin, and beta-lactoglobulin demonstrated antiviral activities. Casein and alpha-lactalbumin gained anti-HIV activity after modification with 3-hydroxyphthalic anhydride. Many milk proteins inhibited HIV reverse transcriptase. Bovine glycolactin, angiogenin-1, lactogenin, casein, alpha-lactalbumin, beta-lactoglobulin, bovine lactoferrampin, and human lactoferrampin inhibited HIV-1 protease and integrase. Several mammalian lactoferrins prevented hepatitis C infection. Lactoferrin, methylated alpha-lactalbumin and methylated beta-lactoglobulin inhibited human cytomegalovirus. Chemically modified alpha-lactalbumin, beta-lactoglobulin and lysozyme, lactoferrin and lactoferricin, methylated alpha-lactalbumin, methylated and ethylated beta-lactoglobulins inhibited HSV. Chemically modified bovine beta-lactoglobulin had antihuman papillomavirus activity. Beta-lactoglobulin, lactoferrin, esterified beta-lactoglobulin, and esterified lactoferrindisplayed anti-avian influenza A (H5N1) activity. Lactoferrin inhibited respiratory syncytial virus, hepatitis B virus, adenovirus, poliovirus, hantavirus, sindbis virus, semliki forest virus, echovirus, and enterovirus. Milk mucin, apolactoferrin, Fe³⁺-lactoferrin, beta-lactoglobulin, human lactadherin, bovine IgG, and bovine kappa-casein demonstrated antihuman rotavirus activity.

Expression of recombinant human lysozyme in egg whites of transgenic hens

Chicken egg lysozyme (cLY) is an enzyme with 129 amino acid (AA) residue enzyme. This enzyme is present not only in chicken egg white but also in mucosal secretions such as saliva and tears. The antibacterial properties of egg white can be attributed to the presence of lysozyme, which is used as an anti-cancer drug and for the treatment of human immunodeficiency virus (HIV) infection. In this study, we constructed a lentiviral vector containing a synthetic cLY signal peptide and a 447 bp synthetic human lysozyme (hLY) cDNA sequence driven by an oviduct-specific ovalbumin promoter, and microinjected into the subgerminal cavity of stage X chick embryos to generate transgenic chicken. The transgene inserted in the chicken chromosomes directs the synthesis and secretion of hLY which has three times higher specific activity than cLY. Three G₁ transgenic chickens were identified, the only female of which expressed recombinant human lysozyme (rhLY) at 57.66 ± 4.10 μg/ml in the egg white and the G₂ transgenic hens of the G₁ transgenic cock A011 expressed rhLY at 48.72 ± 1.54 μg/ml. This experiment demonstrated that transgenic hens with stable oviduct-specific expression of recombinant human lysozyme proteins can be created by microinjection of lentiviral vectors. The results of this research could be contribute to the technological development using transgenic hens as a cost-effective alternative to other mammalian systems, such as cow, sheep and goats, for the production of therapeutic proteins and other applications.

The Role of Cationic Polypeptides in Modulating HIV-1 Infection of the Cervicovaginal Mucosa

The mucosa and overlying fluid of the female reproductive tract (FRT) are portals for the heterosexual transmission of HIV-1. Toward the ongoing development of topically applied microbicides and mucosal vaccines against HIV-1, it is evermore important to understand how the dynamic FRT mucosa is involved in controlling transmission and infection of HIV-1. Cationic peptides and proteins are the principal innate immune effector molecules of mucosal surfaces, and interact in a combinatorial fashion to modulate HIV-1 infection of the cervix and vagina. While cationic peptides and proteins have historically been categorized as antimicrobial or have other host-benefitting roles, an increasing number of these molecules have been found to augment HIV-1 infection and potentially antagonize host defense. Complex environmental factors such as hormonal fluctuations and/or bacterial and viral co-infections provide additional challenges to both experimentation and interpretation of results. In the context of heterosexual transmission of HIV-1, this review explores how various cationic peptides and proteins participate in modulating host defense against HIV-1 of the cervicovaginal mucosa.

Identification and characterization of a novel phage-type like lysozyme from Manila clam, Ruditapes philippinarum

A novel lysozyme gene (RpLysPh) with high similarity to the bacteriophage lysozymes was identified in Manila clam, Ruditapes philippinarum. The full length cDNA of RpLysPh is 828bp and contains a 462bp open reading frame (ORF) that codes for a 154 amino acid protein. Multiple sequence alignment analysis revealed that the three residues essential for catalytic activity in phage-type lysozyme (Glu(20), Asp(29), and Thr(35)) are conserved in RpLysPh. The comparison of the 3D models of RpLysPh and Coxiella burnetii lysozyme also suggested that the active sites involved in the binding of substrate have similar conformations. Phylogenetic analysis suggested that RpLysPh shares a similar origin with the bacterial phage-type lysozyme group. The highest level of expression of RpLysPh was observed in hemocytes, followed by mantle. Induction of RpLysPh expression was observed in gills in response to lipopolysaccharide (LPS), peptidoglycan (PGN), polyinosinic-polycytidylic acid (Poly(I:C)), and whole glucan particles (WGP) challenge. The recombinant protein of RpLysPh showed antibacterial activity against both Gram-positive and Gram-negative bacteria.