Comparison Between Moxifloxacin and Chloramphenicol for the Treatment of Bacterial Eye Infections.

Background: Moxifloxacin is a bactericidal methoxyquinolone used for the treatment of conjunctivitis and prophylactic therapy in cataract and refractive surgeries. Chloramphenicol is a bacteriostatic organochlorine introduced into clinical practice in 1948 and used mainly in topical preparations because of its known toxicity. Objectives: The study aimed to evaluate the in vitro antibacterial effect and the ocular cytotoxicity of these broad-spectrum antibiotics. Methods: Antimicrobic activity was tested on 4 bacteria strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis), and determined through calculation of MIC and half inhibitory concentration for each microorganism. Antibacterial activity was determined by microdilution method after 24 hours' incubation with 2-fold serial dilutions (2.5 mg/mL to 4.883 µg/mL) of moxifloxacin and chloramphenicol. Disk diffusion test were performed according to European Committee on Antimicrobial Susceptibility Testing methodology. Biofilm formation inhibition and biofilm eradication concentration assay were conducted for P aeruginosa and S epidermidis using the microdilution method. Cytotoxicity of antibiotics was evaluated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) colorimetric assay on human corneal cell. Results: Cytotoxicity of antibiotics was evaluated on human epithelial corneal cells after 4 hours treatment by viability assay. Results showed that corneal cell viability was significantly higher after moxifloxacin treatment compared with chloramphenicol (P < 0.01). Moxifloxacin is characterized by a significantly lower MIC and half inhibitory concentration values and a larger inhibition zone for all the strain tested, with high performance in controlling gram-negative growth, compared with chloramphenicol. Moreover, moxifloxacin showed higher activity compared with chloramphenicol in the inhibition of biofilm formation and in the disruption of biofilm, especially against S epidermidis biofilm. Conclusions: The lower corneal cell toxicity and the broader spectrum of antibacterial activity observed with moxifloxacin suggests its use in ophthalmic solution for the treatment of bacterial eye infections.

Ozonated Oil in Liposome Eyedrops Reduces the Formation of Biofilm, Selection of Antibiotic-Resistant Bacteria, and Adhesion of Bacteria to Human Corneal Cells.

The recent attention to the risk of potential permanent eye damage triggered by ocular infections has been leading to a deeper investigation of the current antimicrobials. An antimicrobial agent used in ophthalmology should possess the following characteristics: a broad antimicrobial spectrum, prompt action even in the presence of organic matter, and nontoxicity. The objective of this study is to compare the antimicrobial efficacy of widely used ophthalmic antiseptics containing povidone-iodine, chlorhexidine, and liposomes containing ozonated sunflower oil. We determined the minimum inhibitory concentration (MIC) on various microbial strains: Staphylococcus aureus (ATCC 6538), methicillin-resistant Staphylococcus aureus (ATCC 33591), Staphylococcus epidermidis (ATCC 12228), Pseudomonas aeruginosa (ATCC 9027), and Escherichia coli (ATCC 873). Furthermore, we assessed its efficacy in controlling antibiotic resistance, biofilm formation, and bacterial adhesion. All three antiseptic ophthalmic preparations showed significant anti-microbicidal and anti-biofilm activity, with the liposomes containing ozonated sunflower oil with the highest ability to control antibiotic resistance and bacteria adhesion to human corneal cells.

Relevance of VEGF and CD147 in different SARS-CoV-2 positive digestive tracts characterized by thrombotic damage.

Several evidence suggests that, in addition to the respiratory tract, also the gastrointestinal tract is a main site of severe acute respiratory syndrome CoronaVirus 2 (SARS-CoV-2) infection, as an example of a multi-organ vascular damage, likely associated with poor prognosis. To assess mechanisms SARS-CoV-2 responsible of tissue infection and vascular injury, correlating with thrombotic damage, specimens of the digestive tract positive for SARS-CoV-2 nucleocapsid protein were analyzed deriving from three patients, negative to naso-oro-pharyngeal swab for SARS-CoV-2. These COVID-19-negative patients came to clinical observation due to urgent abdominal surgery that removed different sections of the digestive tract after thrombotic events. Immunohistochemical for the expression of SARS-CoV-2 combined with a panel of SARS-CoV-2 related proteins angiotensin-converting enzyme 2 receptor, cluster of differentiation 147 (CD147), human leukocyte antigen-G (HLA-G), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 was performed. Tissue samples were also evaluated by electron microscopy for ultrastructural virus localization and cell characterization. The damage of the tissue was assessed by ultrastructural analysis. It has been observed that CD147 expression levels correlate with SARS-CoV-2 infection extent, vascular damage and an increased expression of VEGF and thrombosis. The confirmation of CD147 co-localization with SARS-CoV-2 Spike protein binding on gastrointestinal tissues and the reduction of the infection level in intestinal epithelial cells after CD147 neutralization, suggest CD147 as a possible key factor for viral susceptibility of gastrointestinal tissue. The presence of SARS-CoV-2 infection of gastrointestinal tissue might be consequently implicated in abdominal thrombosis, where VEGF might mediate the vascular damage.

Synthesis and biological evaluation of novel rhodanine-based structures with antiviral activity towards HHV-6 virus.

An increased awareness of diseases associated with Human herpesvirus 6 (HHV-6) infection or reactivation has resulted in a growing interest in the evaluation of the best treatment options available for the clinical management of HHV-6 disease. However, no compound has yet been approved exclusively for HHV-6 infection treatment. For this reason, the identification of anti-HHV6 compounds provides a valuable opportunity for developing efficient antiviral therapies. A possible target for antiviral drugs is the virus-cell fusion step. In this study, we synthetized potential fusion intermediates inhibitors based on the rhodanine structure. The obtained derivatives were tested for cytotoxicity and for antiviral activity in human cells infected with HHV6. Level of infection was monitored by viral DNA quantification at different time points up to 7 days post infection. Among the synthetized derivatives, 9e showed a significative inhibitory effect on viral replication that lasted over 7 days, probably attributable to the particular combination of hydrophilic and hydrophobic substituents to the rhodanine moiety. Our results support the use of these amphipathic fusion inhibitors for the treatment of HHV-6 infections.

Late-onset intrauterine growth restriction and HHV-6 infection: A pilot study.

Late-onset Intrauterine growth restriction (IUGR) refers to impaired growth and development of the fetus, characterized by placental morphological abnormalities that affect the fetus's supply of nutrients. Human leukocyte antigen-G (HLA-G) is physiologically expressed during pregnancy, but decreased in normal placenta during the last weeks of gestation possibly inducing childbirth. Several viruses involved in congenital infection, such as herpesviruses, exploit HLA-G expression as an immune-escape mechanism. To date, despite different congenital herpetic infections having been associated with late IUGR, no direct implication of Human herpesvirus 6 (HHV-6) infection has been reported. We evaluated HLA-G expression and HHV-6 infection in 11 placentas from late-onset IUGR newborns and 11 placentas from uncomplicated pregnancies by histopathological and immunohistochemistry analysis. We found higher levels of HLA-G expression and HHV-6 presence in IUGR placenta samples compared with control placenta samples. We report HHV-6 staining in IUGR placenta samples, characterized by high HLA-G expression. These preliminary data suggest a possible involvement of HHV-6 infection in HLA-G deregulation that might affect vessel remodeling and prevent the correct pregnancy outcome in the IUGR condition.

Design of Liposomes Carrying HelixComplex Snail Mucus: Preliminary Studies.

In recent decades liposomes have been used in different field thanks to their ability to act as a vehicle for a wide range of biomolecules, their great versatility and their easy production. The aim of this study was to evaluate liposomes as a vehicle for the actives present in the HelixComplex (HC) snail mucus for topical delivery. Liposomes composed of a mixture of phosphatidylcholine, cholesterol and octadecylamine were prepared with and without HC (empty liposomes) and their biological efficacy was tested by evaluating cell viability and migration. HC-loaded liposomes (LHC) were stable throughout 60 days of observation, and showed interesting effects on wound healing reconstitution. In particular, we observed that 25 µg/mL LHC were already able to induce a higher cell monolayer reconstitution in comparison to the untreated samples and HC treated samples after only 4 h (28% versus 10% and 7%, p = 0.03 and p= 0.003, respectively). The effect was more evident at 24 h in comparison with the untreated control (54% versus 21.2% and 41.6%, p = 0.006 and p = NS, respectively). These results represent a preliminary, but promising, novelty in the delivery strategy of the actives present in the HelixComplex mucus.

Development, optimization and validation of an absolute specific assay for active myeloperoxidase (MPO) and its application in a clinical context: role of MPO specific activity in coronary artery disease.

Background Myeloperoxidase (MPO) is an enzyme with a recognized prognostic role in coronary artery disease (CAD), which is also emerging as a promising biomarker for cardiac risk stratification. However, the lack of a consensus method for its quantification has hindered its implementation in clinical practice. The aim of our work was to optimize an absolute sensitive assay for active MPO without external standards, to validate the method in the clinical context of CAD patients, and to estimate the enzyme specific activity. Methods In order to determine the MPO concentration using fluorescence readings, this ELISA assay exploits the activity of the enzyme recognized by specific antibodies. The assay was validated in a small cohort of patients that included: healthy subjects (n=60); patients with acute myocardial infarction (AMI, n=25); patients with stable CAD (SCAD, n=25) and a concomitant chronic obstructive pulmonary disease (COPD). Then, total MPO concentration and specific activity (activity/total MPO) were determined. Results The assay showed an intra- and inter-assay coefficient of variation of 5.8% and 10.4%, respectively, with a limit of detection (LoD) of 0.074 µU. Both AMI and SCAD patients had higher active and total MPO than controls (p<0.0001 and p<0.01, respectively). The specific activity of MPO was higher in SCAD patients compared to both controls and AMI (p<0.0001). Conclusions The study presents a robust and sensitive method for assaying MPO activity in biological fluids with low variability. Moreover, the determination of the specific activity could provide novel insight into the role of MPO in cardiovascular diseases (CVDs).

Detection of inherited chromosomally integrated HHV-6 (ciHHV-6) in a marker chromosome.

OBJECTIVES: Inherited chromosomally integrated human herpesvirus-6 (ciHHV-6) is characterised by the complete HHV-6 genome integration into the host germ line genome and is vertically transmitted with a Mendelian inheritance. By now, the only relationship between ciHHV-6 and diseases seems to be with angina pectoris. METHODS: We report a case of an 82-year-old man diagnosed with diffuse large B-cell lymphoma (DLBCL) on October 2014. To substantiate the suspicion of ciHHV-6, we analysed peripheral blood mononuclear cells, bone marrow biopsy and pleural effusion-derived mesothelial cells with PCR, RT-PCR and FISH. RESULTS: Virological routine screening by PCR showed the absence of HHV-8 and EBV infections, while the presence of HHV-6 DNA (ie, U22, U42 and U94 HHV-6 genes), with a viral load of about 1.0 genome per cell, strongly suggests ciHHV-6. The RT-PCR showed the positivity only for the immediate-early U94, at low levels of transcription (100±15 transcripts/1 µg RNA). FISH analysis reported a case of inherited ciHHV-6 in 17p chromosome region and, for the first time, in a marker chromosome. CONCLUSIONS: This is the first case of inherited ciHHV-6 in a marker chromosome, possibly elucidating the role of this abnormality in the biology of DLBCL.

Cerebrospinal fluid amounts of HLA-G in dimeric form are strongly associated to patients with MRI inactive multiple sclerosis.

BACKGROUND: The relevance of human leukocyte antigen (HLA)-G in dimeric form in multiple sclerosis (MS) is still unknown. OBJECTIVE: To investigate the contribution of cerebrospinal fluid (CSF) HLA-G dimers in MS pathogenesis. METHODS: CSF amounts of 78-kDa HLA-G dimers were measured by western blot analysis in 80 MS relapsing-remitting MS (RRMS) patients and in 81 inflammatory and 70 non-inflammatory controls. RESULTS: CSF amounts of 78 kDa HLA-G dimers were more frequent in RRMS than in inflammatory (p<0.01) and non-inflammatory controls (p<0.001) and in magnetic resonance imaging (MRI) inactive than in MRI active RRMS (p<0.00001). CONCLUSION: Our findings suggest that HLA-G dimers may be implicated in termination of inflammatory response occurring in MS.

Acute human herpesvirus-6A infection of human mesothelial cells modulates HLA molecules.

Human herpesvirus 6A (HHV-6A) causes ubiquitous infections and has been associated with several diseases in immunosuppressed and immune dysregulated individuals. Although considered a lymphotropic virus, HHV-6A has the potential to infect many cell types, inducing important alterations in the infected cell. In our search for additional potential targets for HHV-6A infection, we analyzed the susceptibility of human mesothelial cells to viral infection. HHV-6A infection was performed and analyzed on primary human mesothelial cells isolated from serous cavity fluid, infected in vitro with a cell-free HHV-6A inoculum. The results demonstrated that mesothelial cells are susceptible to in vitro HHV-6A infection, and more importantly, that the virus induces an alteration of HLA expression on the cell surface, inducing HLA class II and HLA-G de novo expression. Since mesothelial cells play a pivotal role in many processes, including inflammation and antigen presentation, we speculate that, in vivo, this virus-induced perturbation might be correlated to alterations in mesothelium functions.

Impact of soluble HLA-G levels and endometrial NK cells in uterine flushing samples from primary and secondary unexplained infertile women.

The aim of this research was to determine the levels of human leukocyte antigen G (HLA-G) and endometrial Natural Killer ((e)NK) cell percentages in uterine flushing samples from primary and secondary infertile women. sHLA-G levels were lower in the uterine flushing samples from primary infertile women in comparison with women with secondary infertility. Lower CD56+KIR2DL4+ (e)NK cell percentages were detected in primary infertile women compared with secondary infertile women. This is the first study demonstrating that primary and secondary unexplained infertilities are characterized by different basal sHLA-G levels and CD56+KIR2DL4+ (e)NK cell percentages.

SARS-CoV-2 presence in recreational seawater and evaluation of intestine permeability: experimental evidence of low impact on public health.

Introduction: Coastal seawater pollution poses a public health risk due to the potential ingestion of contaminated water during recreational activities. Wastewater-based epidemiology has revealed the abundant presence of SARS-CoV-2 in seawater emitted from wastewater outlets. The objective of this research was to investigate the impact of seawater on SARS-CoV-2 infectivity to assess the safety of recreational activities in seawater. Methods: Wild SARS-CoV-2 was collected from oral swabs of COVID-19 affected patients and incubated for up to 90 min using the following solutions: (a) standard physiological solution (control), (b) reconstructed seawater (3.5% NaCl), and (c) authentic seawater (3.8%). Samples were then exposed to two different host systems: (a) Vero E6 cells expressing the ACE2 SARS-CoV-2 receptor and (b) 3D multi-tissue organoids reconstructing the human intestine. The presence of intracellular virus inside the host systems was determined using plaque assay, quantitative real-time PCR (qPCR), and transmission electron microscopy. Results: Ultrastructural examination of Vero E6 cells revealed the presence of virus particles at the cell surface and in replicative compartments inside cells treated with seawater and/or reconstituted water only for samples incubated up to 2 min. After a 90-min incubation, the presence of the virus and its infectivity in Vero E6 cells was reduced by 90%. Ultrastructural analysis performed in 3D epi-intestinal tissue did not reveal intact viral particles or infection signs, despite the presence of viral nucleic acid detected by qPCR. Indeed, viral genes (Orf1ab and N) were found in the intestinal luminal epithelium but not in the enteric capillaries. These findings suggest that the intestinal tissue is not a preferential entry site for SARS-CoV-2 in the human body. Additionally, the presence of hypertonic saline solution did not increase the susceptibility of the intestinal epithelium to virus penetration; rather, it neutralized its infectivity. Conclusion: Our results indicate that engaging in recreational activities in a seawater environment does not pose a significant risk for COVID-19 infection, despite the possible presence of viral nucleic acid deriving from degraded and fragmented viruses.

Effects of Sulforaphane on SARS­CoV­2 infection and NF­κB dependent expression of genes involved in the COVID­19 'cytokine storm'.

Since its spread at the beginning of 2020, the coronavirus disease 2019 (COVID­19) pandemic represents one of the major health problems. Despite the approval, testing, and worldwide distribution of anti­severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) vaccines, the development of specific antiviral agents targeting the SARS­CoV­2 life cycle with high efficiency, and/or interfering with the associated 'cytokine storm', is highly required. A recent study, conducted by the authors' group indicated that sulforaphane (SFN) inhibits the expression of IL­6 and IL­8 genes induced by the treatment of IB3­1 bronchial cells with a recombinant spike protein of SARS­CoV­2. In the present study, the ability of SFN to inhibit SARS­CoV­2 replication and the expression of pro­inflammatory genes encoding proteins of the COVID­19 'cytokine storm' was evaluated. SARS­CoV­2 replication was assessed in bronchial epithelial Calu­3 cells. Moreover, SARS­CoV­2 replication and expression of pro­inflammatory genes was evaluated by reverse transcription quantitative droplet digital PCR. The effects on the expression levels of NF­κB were assessed by western blotting. Molecular dynamics simulations of NF­kB/SFN interactions were conducted with Gromacs 2021.1 software under the Martini 2 CG force field. Computational studies indicated that i) SFN was stably bound with the NF­κB monomer; ii) a ternary NF­kB/SFN/DNA complex was formed; iii) the SFN interacted with both the protein and the nucleic acid molecules modifying the binding mode of the latter, and impairing the full interaction between the NF­κB protein and the DNA molecule. This finally stabilized the inactive complex. Molecular studies demonstrated that SFN i) inhibits the SARS­CoV­2 replication in infected Calu­3 cells, decreasing the production of the N­protein coding RNA sequences, ii) decreased NF­κB content in SARS­CoV­2 infected cells and inhibited the expression of NF­kB­dependent IL­1ß and IL­8 gene expression. The data obtained in the present study demonstrated inhibitory effects of SFN on the SARS­CoV­2 life cycle and on the expression levels of the pro­inflammatory genes, sustaining the possible use of SFN in the management of patients with COVID­19.

Natural Killer Cells in SARS-CoV-2-Vaccinated Subjects with Increased Effector Cytotoxic CD56dim Cells and Memory-Like CD57+NKG2C+CD56dim Cells.

BACKGROUND: The infection and negative effects of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus) virus are mitigated by vaccines. It is unknown whether vaccination has worked by eliciting robust protective innate immune responses with high affinity. METHODS: Twenty healthy volunteers received three doses of Comirnaty (Pfizer Australia Pty Ltd.) and were evaluated 9 months after the second vaccination and 1 month after the booster dose. The exclusion criteria were the presence of adverse effects following the vaccination, a history of smoking, and heterologous immunization. The inclusion criteria were the absence of prior Coronavirus Disease (COVID)-19 history, the absence of adverse effects, and the absence of comorbidities. Specific phenotype and levels of CD107a and granzyme production by blood NK (natural killer) cells were analyzed after exposure to SARS-CoV-2 spike antigen (Wuhan, Alpha B.1.1.7, Delta B.1.617.2, and Omicron B1.1.529 variants), and related with anti-SARS-CoV-2 antibody production. RESULTS: The booster dose caused early NK CD56dim subset activation and memory-like phenotype. CONCLUSIONS: We report the relevance of the innate immune response, especially NK cells, to SARS-CoV-2 vaccines to guarantee efficient protection against the infection following a booster dose.

Non-classical HLA class I molecules and their potential role in viral infections.

Human Leukocyte Antigens (HLA) are classified in three different classes I, II and III, and represent the key mediators of immune responses, self-tolerance development and pathogen recognition. Among them, non-classical subtypes (HLA-Ib), e.g. HLA-E and HLA-G, are characterize by tolerogenic functions that are often exploited by viruses to evade the host immune responses. In this perspective, we will review the main current data referred to HLA-G and HLA-E and viral infections, as well as the impact on immune response. Data were selected following eligibility criteria accordingly to the reviewed topic. We used a set of electronic databases (Medline/PubMed, Scopus, Web of Sciences (WOS), Cochrane library) for a systematic search until November 2022 using MeSH keywords/terms (i.e. HLA, HLA-G, HLA-E, viral infection, SARS-CoV-2, etc.…). Recent studies support the involvement of non-classical molecules, such as HLA-E and HLA-G, in the control of viral infection. On one side, viruses exploit HLA-G and HLA-E molecule to control host immune activation. On the other side, the expression of these molecules might control the inflammatory condition generated by viral infections. Hence, this review has the aim to summarize the state of art of literature about the modulation of these non-classical HLA-I molecules, to provide a general overview of the new strategies of viral immune system regulation to counteract immune defenses.

Dihydroartemisinin-Ursodeoxycholic Bile Acid Hybrids in the Fight against SARS-CoV-2.

Here, we propose the molecular hybridization of dihydroartemisinin (DHA) and ursodeoxycholic bile acid (UDCA), approved drugs, for the preparation of antiviral agents against SARS-CoV-2. DHA and UDCA were selected on the basis of their recently demonstrated in vitro activity against SARS-CoV-2. A selection of DHA-UDCA-based hybrids obtained by varying the nature of the linkage and the bile acid conjugation point as well as unconjugated DHA and UDCA were tested in vitro for cytotoxicity and anti-SARS-CoV-2 activity on Vero E6 and Calu-3 human lung cells. The hybrid DHA-t-UDCMe, obtained by conjugation via click chemistry on a gram scale, was identified as a potential candidate for SARS-CoV-2 infection treatment due to significant reduction of viral replication, possibly involving ACE2 downregulation, no cytotoxicity, and chemical stability.

SARS-CoV-2 infection as a model to study the effect of cinnamaldehyde as adjuvant therapy for viral pneumonia.

BACKGROUND: The recent pandemic outbursts, due to SARS-CoV-2, have highlighted once more the central role of the inflammatory process in the propagation of viral infection. The main consequence of COVID-19 is the induction of a diffuse pro-inflammatory state, also defined as a cytokine storm, which affects different organs, but mostly the lungs. We aimed to prove the efficacy of cinnamaldehyde, the active compound of cinnamon, as an anti-inflammatory compound, able to reduce SARS-CoV-2 induced cytokine storm. RESULTS: We enrolled 53 COVID-19 patients hospitalized for respiratory failure. The cohort was composed by 39 males and 13 females, aged 65.0 ± 9.8 years. We reported that COVID-19 patients have significantly higher IL-1ß and IL-6 plasma levels compared to non-COVID-19 pneumonia patients. In addition, human mononuclear cells (PBMCs) isolated from SARS-CoV-2 infected patients are significantly more prone to release pro-inflammatory cytokines upon stimuli. We demonstrated, using in vitro cell models, that macrophages are responsible for mediating the pro-inflammatory cytokine storm while lung cells support SARS-CoV-2 replication upon viral infection. In this context, cinnamaldehyde administration significantly reduces SARS-CoV-2-related inflammation by inhibiting NLRP3 mediated IL-1ß release in both PBMCs and THP-1 macrophages, as well as viral replication in CaLu-3 epithelial cells. Lastly, aerosol-administered cinnamaldehyde was able to significantly reduce IL-1ß release in an in vivo lung-inflammatory model. CONCLUSION: The obtained results suggest the possible use of cinnamaldehyde as a co-adjuvant preventive treatment for COVID-19 disease together with vaccination, but also as a promising dietary supplement to reduce, more broadly, viral induced inflammation.

SARS-CoV-2 viral entry and replication is impaired in Cystic Fibrosis airways due to ACE2 downregulation.

As an inherited disorder characterized by severe pulmonary disease, cystic fibrosis could be considered a comorbidity for coronavirus disease 2019. Instead, current clinical evidence seems to be heading in the opposite direction. To clarify whether host factors expressed by the Cystic Fibrosis epithelia may influence coronavirus disease 2019 progression, here we describe the expression of SARS-CoV-2 receptors in primary airway epithelial cells. We show that angiotensin converting enzyme 2 (ACE2) expression and localization are regulated by Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Consistently, our results indicate that dysfunctional CFTR channels alter susceptibility to SARS-CoV-2 infection, resulting in reduced viral entry and replication in Cystic Fibrosis cells. Depending on the pattern of ACE2 expression, the SARS-CoV-2 spike (S) protein induced high levels of Interleukin 6 in healthy donor-derived primary airway epithelial cells, but a very weak response in primary Cystic Fibrosis cells. Collectively, these data support that Cystic Fibrosis condition may be at least partially protecting from SARS-CoV-2 infection.

Characterization of Neochloris oleoabundans under Different Cultivation Modes and First Results on Bioactivity of Its Extracts against HCoV-229E Virus.

Microalgae are proposed in several biotechnological fields because of their ability to produce biomass enriched in high-value compounds according to cultivation conditions. Regarding the health sector, an emerging area focuses on natural products exploitable against viruses. This work deals with the characterization of the green microalga Neochloris oleoabundans cultivated under autotrophic and mixotrophic conditions as a source of whole aqueous extracts, tested as antivirals against HCoV-229E (Coronaviridae family). Glucose was employed for mixotrophic cultures. Growth and maximum quantum yield of photosystem II were monitored for both cultivations. Algae extracts for antiviral tests were prepared using cultures harvested at the early stationary phase of growth. Biochemical and morphological analyses of algae indicated a different content of the most important classes of bioactive compounds with antiviral properties (lipids, exo-polysaccharides, and total phenolics, proteins and pigments). To clarify which phase of HCoV-229E infection on MRC-5 fibroblast cells was affected by N. oleoabundans extracts, four conditions were tested. Extracts gave excellent results, mainly against the first steps of virus infection. Notwithstanding the biochemical profile of algae/extracts deserves further investigation, the antiviral effect may have been mainly promoted by the combination of proteins/pigments/phenolics for the extract derived from autotrophic cultures and of proteins/acidic exo-polysaccharides/lipids in the case of mixotrophic ones.