Prevalence of hepatitis D virus infection in Central Italy has remained stable across the last 2 decades with dominance of subgenotypes 1 and characterized by elevated viral replication

OBJECTIVES

Here we investigate Hepatitis D virus (HDV)-prevalence in Italy and its fluctuations over time and we provide an extensive characterization of HDV-infected patients.

METHODS

The rate of HDV seroprevalence and HDV chronicity was assessed in 1579 hepatitis B surface antigen (HBsAg)+ patients collected from 2005 to 2022 in Central Italy.

RESULTS

In total, 45.3% of HBsAg+ patients received HDV screening with an increasing temporal trend: 15.6% (2005-2010), 45.0% (2011-2014), 49.4% (2015-2018), 71.8% (2019-2022). By multivariable model, factors correlated with the lack of HDV screening were alanine-aminotransferase (ALT) less than two times of upper limit of normality (<2ULN) and previous time windows (P <0.002). Furthermore, 13.4% of HDV-screened patients resulted anti-HDV+ with a stable temporal trend. Among them, 80.8% had detectable HDV-ribonucleic acid (RNA) (median [IQR]:4.6 [3.6-5.6] log copies/ml) with altered ALT in 89.3% (median [IQR]:92 [62-177] U/L). Anti-HDV+ patients from Eastern/South-eastern Europe were younger than Italians (44 [37-54] vs 53 [47-62] years, P <0.0001), less frequently nucleos(t)ide analogs (NUC)-treated (58.5% vs 80%, P = 0.026) with higher HDV-RNA (4.8 [3.6-5.8] vs 3.9 [1.4-4.9] log copies/ml, P = 0.016) and HBsAg (9461 [4159-24,532] vs 4447 [737-13,336] IU/ml, P = 0.032). Phylogenetic analysis revealed the circulation of HDV subgenotype 1e (47.4%) and -1c (52.6%). Notably, subgenotype 1e correlated with higher ALT than 1c (168 [89-190] vs 58 [54-88] U/l, P = 0.015) despite comparable HDV-RNA.

CONCLUSIONS

HDV-screening awareness is increasing over time even if some gaps persist to achieve HDV screening in all HBsAg+ patients. HDV prevalence in tertiary care centers tend to scarcely decline in native/non-native patients. Detection of subgenotypes, triggering variable inflammatory stimuli, supports the need to expand HDV molecular characterization.

Unexpected rise in the circulation of complex HBV variants enriched of HBsAg vaccine-escape mutations in HBV genotype-D: potential impact on HBsAg detection/quantification and vaccination strategies

Specific HBsAg mutations are known to hamper HBsAg recognition by neutralizing antibodies thus challenging HBV-vaccination efficacy. Nevertheless, information on their impact and spreading over time is limited. Here, we characterize the circulation of vaccine-escape mutations from 2005 to 2019 and their correlation with virological parameters in a large cohort of patients infected with HBV genotype-D (N = 947), dominant in Europe. Overall, 17.7% of patients harbours ≥1 vaccine-escape mutation with the highest prevalence in subgenotype-D3. Notably, complex profiles (characterized by ≥2 vaccine-escape mutations) are revealed in 3.1% of patients with a prevalence rising from 0.4% in 2005-2009 to 3.0% in 2010-2014 and 5.1% in 2015-2019 (P = 0.007) (OR[95%CI]:11.04[1.42-85.58], P = 0.02, by multivariable-analysis). The presence of complex profiles correlates with lower HBsAg-levels (median[IQR]:40[0-2905]IU/mL for complex profiles vs 2078[115-6037]IU/ml and 1881[410-7622]IU/mL for single or no vaccine-escape mutation [P < 0.02]). Even more, the presence of complex profiles correlates with HBsAg-negativity despite HBV-DNA positivity (HBsAg-negativity in 34.8% with ≥2 vaccine-escape mutations vs 6.7% and 2.3% with a single or no vaccine-escape mutation, P < 0.007). These in-vivo findings are in keeping with our in-vitro results showing the ability of these mutations in hampering HBsAg secretion or HBsAg recognition by diagnostic antibodies. In conclusion, vaccine-escape mutations, single or in complex profiles, circulate in a not negligible fraction of HBV genotype-D infected patients with an increasing temporal trend, suggesting a progressive enrichment in the circulation of variants able to evade humoral responses. This should be considered for a proper clinical interpretation of HBsAg-results and for the development of novel vaccine formulations for prophylactic and therapeutic purposes.

Antiviral activity of nitazoxanide against Morbillivirus infections

The measles virus (MeV) and canine distemper virus (CDV) belong to the genus Morbillivirus of the Paramyxoviridae family. They are enveloped viruses harboring a non-segmented negative-sense RNA. Morbilliviruses are extremely contagious and transmitted through infectious aerosol droplets. Both MeV and CDV may cause respiratory infections and fatal encephalitis, although a high incidence of brain infections is unique to CDV. Despite the availability of a safe and effective vaccine against these viruses, in recent years we are witnessing a strong resurgence of Morbillivirus infection. Measles still kills more than 100,000 people each year, and CDV causes widespread outbreaks, especially among wild animals, including non-human primates. No drugs are currently approved for MeV and CDV. Therefore, the identification of effective antiviral agents represents an unmet medical need. Here, we have investigated the potential antiviral properties of nitazoxanide (NTZ) against MeV and CDV. Antiviral activity was explored with live virus and cell-based assays. NTZ is a thiazolide that is approved by the FDA as an antiprotozoal agent for the treatment of Giardia intestinalis and Cryptosporidium parvum. Further, nitazoxanide and its metabolite tizoxanide have recently emerged as broad-spectrum antiviral agents. We found that NTZ blocks the MeV and CDV replication, acting at the post-entry level. Moreover, we showed that NTZ affects the function of the viral fusion protein (F), impairing viral spread. Our results indicate that NTZ should be further explored as a therapeutic option in measles and canine distemper virus treatment.

The FDA-approved drug nitazoxanide is a potent inhibitor of human seasonal coronaviruses acting at postentry level: effect on the viral spike glycoprotein

Coronaviridae is recognized as one of the most rapidly evolving virus family as a consequence of the high genomic nucleotide substitution rates and recombination. The family comprises a large number of enveloped, positive-sense single-stranded RNA viruses, causing an array of diseases of varying severity in animals and humans. To date, seven human coronaviruses (HCoV) have been identified, namely HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, which are globally circulating in the human population (seasonal HCoV, sHCoV), and the highly pathogenic SARS-CoV, MERS-CoV and SARS-CoV-2. Seasonal HCoV are estimated to contribute to 15-30% of common cold cases in humans; although diseases are generally self-limiting, sHCoV can sometimes cause severe lower respiratory infections and life-threatening diseases in a subset of patients. No specific treatment is presently available for sHCoV infections. Herein we show that the anti-infective drug nitazoxanide has a potent antiviral activity against three human endemic coronaviruses, the Alpha-coronaviruses HCoV-229E and HCoV-NL63, and the Beta-coronavirus HCoV-OC43 in cell culture with IC50 ranging between 0.05 and 0.15 μg/mL and high selectivity indexes. We found that nitazoxanide does not affect HCoV adsorption, entry or uncoating, but acts at postentry level and interferes with the spike glycoprotein maturation, hampering its terminal glycosylation at an endoglycosidase H-sensitive stage. Altogether the results indicate that nitazoxanide, due to its broad-spectrum anti-coronavirus activity, may represent a readily available useful tool in the treatment of seasonal coronavirus infections.

Thiazolide Prodrug Esters and Derived Peptides: Synthesis and Activity

Amino acid ester prodrugs of the thiazolides, introduced to improve the pharmacokinetic parameters of the parent drugs, proved to be stable as their salts but were unstable at pH > 5. Although some of the instability was due to simple hydrolysis, we have found that the main end products of the degradation were peptides formed by rearrangement. These peptides were stable solids: they maintained significant antiviral activity, and in general, they showed improved pharmacokinetics (better solubility and reduced clearance) compared to the parent thiazolides. We describe the preparation and evaluation of these peptides.

Molecular and Structural Aspects of Clinically Relevant Mutations of SARS-CoV-2 RNA-Dependent RNA Polymerase in Remdesivir-Treated Patients

(1) Background: SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) is a promising therapeutic target to fight COVID-19, and many RdRp inhibitors nucleotide/nucleoside analogs, such as remdesivir, have been identified or are in clinical studies. However, the appearance of resistant mutations could reduce their efficacy. In the present work, we structurally evaluated the impact of RdRp mutations found at baseline in 39 patients treated with remdesivir and associated with a different degree of antiviral response in vivo. (2) Methods: A refined bioinformatics approach was applied to assign SARS-CoV-2 clade and lineage, and to define RdRp mutational profiles. In line with such a method, the same mutations were built and analyzed by combining docking and thermodynamics evaluations with both molecular dynamics and representative pharmacophore models. (3) Results: Clinical studies revealed that patients bearing the most prevalent triple mutant P323L+671S+M899I, which was present in 41% of patients, or the more complex mutational profile P323L+G671S+L838I+D738Y+K91E, which was found with a prevalence of 2.6%, showed a delayed reduced response to remdesivir, as confirmed by the increase in SARS-CoV-2 viral load and by a reduced theoretical binding affinity versus RdRp (ΔGbindWT = -122.70 kcal/mol; ΔGbindP323L+671S+M899I = -84.78 kcal/mol; ΔGbindP323L+G671S+L838I+D738Y+K91E = -96.74 kcal/mol). Combined computational approaches helped to rationalize such clinical observations, offering a mechanistic understanding of the allosteric effects of mutants on the global motions of the viral RNA synthesis machine and in the changes of the interactions patterns of remdesivir during its binding.

Deciphering the Broad Antimicrobial Activity of Melaleuca alternifolia Tea Tree Oil by Combining Experimental and Computational Investigations

Tea Tree Oil (TTO) is an essential oil obtained from the distillation of Melaleuca alternifolia leaves and branches. Due to its beneficial properties, TTO is widely used as an active ingredient in antimicrobial preparations for topical use or in cosmetic products and contains about 100 different compounds, with terpinen-4-ol, γ-terpinene and 1,8-cineole (or eucalyptol) being the molecules most responsible for its biological activities. In this work, the antimicrobial activity of whole TTO and these three major components was evaluated in vitro against fungi, bacteria and viruses. Molecular dynamics simulations were carried out on a bacterial membrane model and a Coxsackievirus B4 viral capsid, to propose an atomistic explanation of their mechanism of action. The obtained results indicate that the strong antimicrobial activity of TTO is attributable to the induction of an altered membrane functionality, mediated by the incorporation of its components within the lipid bilayer, and to a possible ability of the compounds to bind and alter the structural properties of the viral capsid.

The second-generation thiazolide haloxanide is a potent inhibitor of avian influenza virus replication

The emergence of new avian influenza virus (AIV) strains able to infect humans represents a serious threat to global human health. In addition to surveillance and vaccine development, antiviral therapy remains crucial for AIV control; however, the increase in drug-resistant AIV strains underscores the need for novel approaches to anti-influenza chemotherapy. We have previously shown that the thiazolide anti-infective nitazoxanide (NTZ) inhibits influenza A/PuertoRico/8/1934(H1N1) virus replication, and this effect was associated with inhibition of viral hemagglutinin (HA) maturation. Herein we investigated the activity of the second-generation thiazolide haloxanide (HLN) against H5N9, H7N1 and H1N1 AIV infection in vitro, and explored the mechanism of the antiviral action. Using the A/chicken/Italy/9097/1997(H5N9) AIV as a model, we show that HLN and its precursor p-haloxanide are more effective than NTZ against AIV, with IC₅₀ ranging from 0.03 to 0.1 μg/ml, and SI ranging from 200 to >700, depending on the multiplicity of infection. Haloxanide did not affect AIV entry into target cells and did not cause a general inhibition of viral protein expression, whereas it acted at post-translational level by inhibiting HA maturation at a stage preceding resistance to endoglycosidase-H digestion. Importantly, this effect was independent of the AIV-HA subtype and the host cell. Immunomicroscopy and receptor-binding studies confirmed that HLN-induced alterations impair AIV-HA trafficking to the host cell plasma membrane, a key step for viral morphogenesis. The results indicate that haloxanide could provide a new tool for treatment of avian influenza virus infections.

Inhibition of viral protein translation by indomethacin in vesicular stomatitis virus infection: role of eIF2α kinase PKR

Indomethacin, a cyclooxygenase‐1 and ‐2 inhibitor widely used in the clinic for its potent anti‐inflammatory/analgesic properties, possesses antiviral activity against several viral pathogens; however, the mechanism of antiviral action remains elusive. We have recently shown that indomethacin activates the double‐stranded RNA (dsRNA)‐dependent protein kinase R (PKR) in human colon cancer cells. Because of the important role of PKR in the cellular defence response against viral infection, herein we investigated the effect of indomethacin on PKR activity during infection with the prototype rhabdovirus vesicular stomatitis virus. Indomethacin was found to activate PKR in an interferon‐ and dsRNA‐independent manner, causing rapid (< 5 min) phosphorylation of eukaryotic initiation factor‐2 α‐subunit (eIF2α). These events resulted in shutting off viral protein translation and blocking viral replication (IC₅₀ = 2 μM) while protecting host cells from virus‐induced damage. Indomethacin did not affect eIF2α kinases PKR‐like endoplasmic reticulum‐resident protein kinase (PERK) and general control non‐derepressible‐2 (GCN2) kinase, and was unable to trigger eIF2α phosphorylation in the presence of PKR inhibitor 2‐aminopurine. In addition, small‐interfering RNA‐mediated PKR gene silencing dampened the antiviral effect in indomethacin‐treated cells. The results identify PKR as a critical target for the antiviral activity of indomethacin and indicate that eIF2α phosphorylation could be a key element in the broad spectrum antiviral activity of the drug.

Prostaglandin A1 inhibits avian influenza virus replication at a postentry level: Effect on virus protein synthesis and NF-κB activity

Influenza A viruses (IAV) have the potential to cause devastating pandemics. In recent years, the emergence of new avian strains able to infect humans represents a serious threat to global human health. The increase in drug-resistant IAV strains underscores the need for novel approaches to anti-influenza chemotherapy. Herein we show that prostaglandin-A1 (PGA1) possesses antiviral activity against avian IAV, including H5N9, H7N1 and H1N1 strains, acting at a level different from the currently available anti-influenza drugs. PGA1 acts at postentry level, causing dysregulation of viral protein synthesis and preventing virus-induced disassembly of host microtubular network and activation of pro-inflammatory factor NF-κB. The antiviral activity is dependent on the presence of a cyclopentenone ring structure and is associated with activation of a cytoprotective heat shock response in infected cells. The results suggest that cyclopentenone prostanoids or prostanoids-derived molecules may represent a new tool to combat avian influenza virus infection.

The proteasome inhibitor bortezomib is a potent inducer of zinc finger AN1-type domain 2a gene expression: role of heat shock factor 1 (HSF1)-heat shock factor 2 (HSF2) heterocomplexes

The zinc finger AN1-type domain 2a gene, also known as arsenite-inducible RNA-associated protein (AIRAP), was recently identified as a novel human canonical heat shock gene strictly controlled by heat shock factor (HSF) 1. Little is known about AIRAP gene regulation in human cells. Here we report that bortezomib, a proteasome inhibitor with anticancer and antiangiogenic properties used in the clinic for treatment of multiple myeloma, is a potent inducer of AIRAP expression in human cells. Using endothelial cells as a model, we unraveled the molecular mechanism regulating AIRAP expression during proteasome inhibition. Bortezomib induces AIRAP expression at the transcriptional level early after treatment, concomitantly with polyubiquitinated protein accumulation and HSF activation. AIRAP protein is detected at high levels for at least 48 h after bortezomib exposure, together with the accumulation of HSF2, a factor implicated in differentiation and development regulation. Different from heat-mediated induction, in bortezomib-treated cells, HSF1 and HSF2 interact directly, forming HSF1-HSF2 heterotrimeric complexes recruited to a specific heat shock element in the AIRAP promoter. Interestingly, whereas HSF1 has been confirmed to be critical for AIRAP gene transcription, HSF2 was found to negatively regulate AIRAP expression after bortezomib treatment, further emphasizing an important modulatory role of this transcription factor under stress conditions. AIRAP function is still not defined. However, the fact that AIRAP is expressed abundantly in primary human cells at bortezomib concentrations comparable with plasma levels in treated patients suggests that AIRAP may participate in the regulatory network controlling proteotoxic stress during bortezomib treatment.

Thiazolides, a new class of antiviral agents effective against rotavirus infection, target viral morphogenesis, inhibiting viroplasm formation

Rotaviruses, nonenveloped viruses presenting a distinctive triple-layered particle architecture enclosing a segmented double-stranded RNA genome, exhibit a unique morphogenetic pathway requiring the formation of cytoplasmic inclusion bodies called viroplasms in a process involving the nonstructural viral proteins NSP5 and NSP2. In these structures the concerted packaging and replication of the 11 positive-polarity single-stranded RNAs take place to generate the viral double-stranded RNA (dsRNA) genomic segments. Rotavirus infection is a leading cause of gastroenteritis-associated severe morbidity and mortality in young children, but no effective antiviral therapy exists. Herein we investigate the antirotaviral activity of the thiazolide anti-infective nitazoxanide and reveal a novel mechanism by which thiazolides act against rotaviruses. Nitazoxanide and its active circulating metabolite, tizoxanide, inhibit simian A/SA11-G3P[2] and human Wa-G1P[8] rotavirus replication in different types of cells with 50% effective concentrations (EC50s) ranging from 0.3 to 2 μg/ml and 50% cytotoxic concentrations (CC50s) higher than 50 μg/ml. Thiazolides do not affect virus infectivity, binding, or entry into target cells and do not cause a general inhibition of viral protein expression, whereas they reduce the size and alter the architecture of viroplasms, decreasing rotavirus dsRNA formation. As revealed by protein/protein interaction analysis, confocal immunofluorescence microscopy, and viroplasm-like structure formation analysis, thiazolides act by hindering the interaction between the nonstructural proteins NSP5 and NSP2. Altogether the results indicate that thiazolides inhibit rotavirus replication by interfering with viral morphogenesis and may represent a novel class of antiviral drugs effective against rotavirus gastroenteritis.

Thiazolides, a new class of anti-influenza molecules targeting viral hemagglutinin at the post-translational level

The emergence of highly contagious influenza A virus strains, such as the new H1N1 swine influenza, represents a serious threat to global human health. Efforts to control emerging influenza strains focus on surveillance and early diagnosis, as well as development of effective vaccines and novel antiviral drugs. Herein we document the anti-influenza activity of the anti-infective drug nitazoxanide and its active circulating-metabolite tizoxanide and describe a class of second generation thiazolides effective against influenza A virus. Thiazolides inhibit the replication of H1N1 and different other strains of influenza A virus by a novel mechanism: they act at post-translational level by selectively blocking the maturation of the viral hemagglutinin at a stage preceding resistance to endoglycosidase H digestion, thus impairing hemagglutinin intracellular trafficking and insertion into the host plasma membrane, a key step for correct assembly and exit of the virus from the host cell. Targeting the maturation of the viral glycoprotein offers the opportunity to disrupt the production of infectious viral particles attacking the pathogen at a level different from the currently available anti-influenza drugs. The results indicate that thiazolides may represent a new class of antiviral drugs effective against influenza A infection.

Antiviral Activity of Proteasome Inhibitors in Herpes Simplex Virus-1 Infection: Role of Nuclear Factor-κB

Background

Herpes simplex virus type 1 (HSV-1) is a potent inducer of nuclear factor-κB (NF-κB), a cellular transcription factor with a crucial role in promoting inflammation and controlling cell proliferation and survival.

Objectives

On the basis of the recent demonstration that HSV-1-induced NF-κB is actively recruited to κB-binding sites in the HSV-1 infected-cell protein 0 (ICP0) promoter enhancing viral transcription and replication, we investigated the effect of proteasome inhibitors MG132, MG115 and epoxomicin, which block NF-κB function by preventing the degradation of the inhibitory proteins IκBα, on HSV-1-induced NF-κB activation and viral replication.

Methods

Antiviral activity of proteasome inhibitors was analysed in HSV-1-infected HEp2 cells by determining infective virus titres by CPE50%, viral RNA synthesis by RT-PCR, and viral protein synthesis by immunoblot analysis or immunofluorescence. ICP0 transcription was studied in transient transfection experiments using the ICP0 promoter-luciferase IE1-Luc construct. IκBα degradation and NF-κB activity were determined by immunoblot analysis and EMSA, respectively.

Results

Proteasome inhibitors were found to prevent HSV-1-induced NF-κB activation in the early phase of infection. Block of virus-induced NF-κB activation resulted in inhibiting HSV-1 ICP0 gene expression, in decreasing the level of immediate-early and late viral proteins, and ultimately in greatly suppressing viral replication. The antiviral effect was lost if treatment was started after NF-κB activation, and appeared to be independent of the HSV-1-induced activation of the JNK pathway.

Conclusions

Proteasome inhibitors possess NF-κB-dependent antiherpetic activity. The results described further identify the IKK/NF-κB pathway as a suitable target for novel antiherpetic drugs.

Antiviral activity of proteasome inhibitors in herpes simplex virus-1 infection: role of nuclear factor-kappaB

BACKGROUND

Herpes simplex virus type 1 (HSV-1) is a potent inducer of nuclear factor-KB (NF-kappaB), a cellular transcription factor with a crucial role in promoting inflammation and controlling cell proliferation and survival.

OBJECTIVES

On the basis of the recent demonstration that HSV-1-induced NF-kappaB is actively recruited to KB-binding sites in the HSV-1 infected-cell protein 0 (ICPO) promoter enhancing viral transcription and replication, we investigated the effect of proteasome inhibitors MG132, MG115 and epoxomicin, which block NF-kappaB function by preventing the degradation of the inhibitory proteins IkappaBalpha, on HSV-1-induced NF-kappaB activation and viral replication.

METHODS

Antiviral activity of proteasome inhibitors was analysed in HSV-1-infected HEp2 cells by determining infective virus titres by CPE50%, viral RNA synthesis by RT-PCR, and viral protein synthesis by immunoblot analysis or immunofluorescence. ICPO transcription was studied in transient transfection experiments using the ICPO promoter-luciferase IE1-Luc construct. IkappaBalpha degradation and NF-kappaB activity were determined by immunoblot analysis and EMSA, respectively.

RESULTS

Proteasome inhibitors were found to prevent HSV-1-induced NF-kappaB activation in the early phase of infection. Block of virus-induced NF-kappaB activation resulted in inhibiting HSV-1 ICPO gene expression, in decreasing the level of immediate-early and late viral proteins, and ultimately in greatly suppressing viral replication. The antiviral effect was lost if treatment was started after NF-kappaB activation, and appeared to be independent of the HSV-1-induced activation of the JNK pathway.

CONCLUSIONS

Proteasome inhibitors possess NF-kappaB-dependent antiherpetic activity. The results described further identify the IKK/NF-kappaB pathway as a suitable target for novel antiherpetic drugs.

The IkappaB kinase is a key factor in triggering influenza A virus-induced inflammatory cytokine production in airway epithelial cells

Influenza A viruses continue to represent a severe threat worldwide, causing large epidemics and pandemics responsible for thousands of deaths every year. Excessive inflammation due to overabundant production of proinflammatory cytokines by airway epithelial cells is considered an important factor in disease pathogenesis. Here we report that influenza A virus induced IkappaB kinase (IKK) activity in human airway epithelial A549 cells, resulting in persistent activation of nuclear factor-kappaB (NF-kappaB), a critical regulator of the inflammatory response. Although lung epithelial cells are highly sensitive to stimulation of the IKK/NF-kappaB pathway by influenza virus infection, NF-kappaB was not activated in several non-pulmonary cells permissive to the virus, indicating a cell-specific response. Moreover, NF-kappaB was not essential for virus replication but triggered the expression of proinflammatory cytokines in infected lung cells and was directly responsible for production of high levels of interleukin-8, a chemokine associated with influenza-induced inflammation and airway pathology. We also report that 9-deoxy-delta9,delta12-13,14-dihydro-prostaglandin D2, a cyclopentenone prostanoid with therapeutic efficacy against influenza in preclinical studies, was a powerful inhibitor of influenza virus-induced IKK activity and interleukin-8 production by human pulmonary cells. The results identify IKK as an important factor in triggering influenza virus-induced inflammatory reactions in pulmonary epithelium, suggesting novel therapeutic approaches in the treatment of influenza.