Lobar pneumonia due to human metapneumovirus: a case report.

Human metapneumovirus (hMPV) is a respiratory pathogen that can cause lower respiratory tract infections and pneumonia in immunocompetent adults. Pneumonia caused by hMPV is reportedly more likely to cause bronchial wall thickening and ground-glass opacity (GGO). A 44-year-old woman with no significant medical history developed fever, cough, and nausea. Computed tomography of the chest showed scattered GGOs in the right upper lobe and infiltrating shadows with air bronchograms in the left lingual and bilateral lower lobes. The patient was admitted to our hospital for further evaluation. Atypical pneumonia was suspected and lascufloxacin (LSFX) was started. Multiplex polymerase chain reaction (PCR) detected hMPV on hospital day 2 using the FilmArray Respiratory Panel 2.1. Pneumonia due to hMPV was suspected and LSFX was discontinued. The patient subsequently showed spontaneous improvement and was discharged on hospital day 6 after admission. After discharge, pneumonia continued to improve. Early detection of respiratory pathogens using multiplex PCR can help determine the appropriate treatment strategy. As hMPV can also cause lobar pneumonia, we should consider pneumonia due to hMPV in the differential diagnosis of lobar pneumonia.

Probenecid Inhibits Human Metapneumovirus (HMPV) Replication In Vitro and in BALB/c Mice.

Human metapneumovirus (HMPV) is an important cause of acute respiratory tract infection and causes significant morbidity and mortality. There is no specific antiviral drug to treat HMPV or vaccine to prevent HMPV. This study determined if probenecid, a host-targeting antiviral drug, had prophylactic (pre-virus) or therapeutic (post-virus) efficacy to inhibit HMPV replication in LLC-MK2 cells in vitro and in the lungs of BALB/c mice. This study showed that ≥0.5 µM probenecid significantly inhibited HMPV replication in vitro, and 2-200 mg/kg probenecid prophylaxis or treatment reduced HMPV replication in BALB/c mice.

Human monoclonal antibodies protect against viral-mediated pneumococcal superinfection.

Introduction: Community-acquired pneumonia (CAP) is a global health concern, with 25% of cases attributed to Streptococcus pneumoniae (Spn). Viral infections like influenza A virus (IAV), respiratory syncytial virus (RSV), and human metapneumovirus (hMPV) increase the risk of Spn, leading to severe complications due to compromised host immunity. Methods: We evaluated the efficacy of an anti-PhtD monoclonal antibody (mAb) cocktail therapy (PhtD3 + 7) in improving survival rates in three viral/bacterial coinfection models: IAV/Spn, hMPV/Spn, and RSV/Spn. Results: The PhtD3 + 7 mAb cocktail outperformed antiviral mAbs, resulting in prolonged survival. In the IAV/Spn model, it reduced bacterial titers in blood and lungs by 2-4 logs. In the hMPV/Spn model, PhtD3 + 7 provided greater protection than the hMPV-neutralizing mAb MPV467, significantly reducing bacterial titers. In the RSV/Spn model, PhtD3 + 7 offered slightly better protection than the antiviral mAb D25, uniquely decreasing bacterial titers in blood and lungs. Discussion: Given the threat of antibiotic resistance, our findings highlight the potential of anti-PhtD mAb therapy as an effective option for treating viral and secondary pneumococcal coinfections.

The HRA2pl fusion peptide exerts in vitro antiviral activity against human respiratory paramyxoviruses and pneumoviruses.

Acute respiratory infections are a group of diseases caused by viruses, bacteria, and parasites that mainly affect children until the age of 5 and immunocompromised senior adults. In Mexico, these infections are the main cause of morbidity in children, with more than 26 million cases of respiratory infections reported by the Secretariat of Health, in 2019. The human respiratory syncytial virus (hRSV), the human metapneumovirus (hMPV), and the human parainfluenza-2 (hPIV-2) are responsible for many respiratory infections. Currently, palivizumab, a monoclonal antibody against the fusion protein F, is the treatment of choice against hRSV infections. This protein is being studied for the design of antiviral peptides that act by inhibiting the fusion of the virus and the host cell. Therefore, we examined the antiviral activity of the HRA2pl peptide, which competes the heptad repeat A domain of the F protein of hMPV. The recombinant peptide was obtained using a viral transient expression system. The effect of the fusion peptide was evaluated with an in vitro entry assay. Moreover, the effectiveness of HRA2pl was examined in viral isolates from clinical samples obtained from patients with infections caused by hRSV, hMPV, or hPIV-2, by evaluating the viral titer and the syncytium size. The HRA2pl peptide affected the viruses' capacity of entry, resulting in a 4-log decrease in the viral titer compared to the untreated viral strains. Additionally, a 50% reduction in the size of the syncytium was found. These results demonstrate the antiviral potential of HRA2pl in clinical samples, paving the way toward clinical trials.

Drug Repurposing for Therapeutic Discovery against Human Metapneumovirus Infection.

Human metapneumovirus (HMPV) is recognized as an important cause of pneumonia in infants, in the elderly, and in immunocompromised individuals worldwide. The absence of an antiviral treatment or vaccine strategy against HMPV infection creates a high burden on the global health care system. Drug repurposing has become increasingly attractive for the treatment of emerging and endemic diseases as it requires less research and development costs than traditional drug discovery. In this study, we developed an in vitro medium-throughput screening assay that allows for the identification of novel anti-HMPV drugs candidates. Out of ~2,400 compounds, we identified 11 candidates with a dose-dependent inhibitory activity against HMPV infection. Additionally, we further described the mode of action of five anti-HMPV candidates with low in vitro cytotoxicity. Two entry inhibitors, Evans Blue and aurintricarboxylic acid, and three post-entry inhibitors, mycophenolic acid, mycophenolate mofetil, and 2,3,4-trihydroxybenzaldehyde, were identified. Among them, the mycophenolic acid series displayed the highest levels of inhibition, due to the blockade of intracellular guanosine synthesis. Importantly, MPA has significant potential for drug repurposing as inhibitory levels are achieved below the approved human oral dose. Our drug-repurposing strategy proved to be useful for the rapid discovery of novel hit candidates to treat HMPV infection and provide promising novel templates for drug design.

Antiviral strategies against human metapneumovirus: Targeting the fusion protein.

Human metapneumoviruses have emerged in the past decades as an important global pathogen that causes severe upper and lower respiratory tract infections. Children under the age of 2, the elderly and immunocompromised individuals are more susceptible to HMPV infection than the general population due to their suboptimal immune system. Despite the recent discovery of HMPV as a novel important respiratory virus, reports have rapidly described its epidemiology, biology, and pathogenesis. However, progress is still to be made in the development of vaccines and drugs against HMPV infection as none are currently available. Herein, we discuss the importance of HMPV and review the reported strategies for anti-HMPV drug candidates. We also present the fusion protein as a promising antiviral drug target due to its multiple roles in the HMPV lifecycle. This key viral protein has previously been targeted by a range of inhibitors, which will be discussed as they represent opportunities for future drug design.

Epicatechin analogues may hinder human parainfluenza virus infection by inhibition of hemagglutinin neuraminidase protein and prevention of cellular entry.

Human parainfluenza viruses (HPIVs) are ( -)ssRNA viruses belonging to Paramyoviridaie family. They are one of the leading causes of mortality in infants and young children and can cause ailments like croup, bronchitis, and pneumonia. Currently, no antiviral medications or vaccines are available to effectively treat parainfluenza. This necessitates the search for a novel and effective treatment. Computer-aided drug design (CADD) methodology can be utilized to discover target-based inhibitors with high accuracy in less time. A library of 45 phytocompounds with immunomodulatory properties was prepared. Thereafter, molecular docking studies were conducted to characterize the binding behavior of ligand in the binding pocket of HPIV3 HN protein. The physicochemical properties for screened compounds were computed, and the top hits from docking studies were further analyzed and validated using molecular dynamics simulation studies using the Desmond module of Schrodinger Suite 2021-1, followed by MM/GBSA analysis. The compounds CID:72276 (1) and CID:107905 (2) emerged as lead compounds of our in silico investigation. Further in vitro studies will be required to prove the efficacy of lead compounds as inhibitors and to determine the exact mechanism of their inhibition. Computational studies predict three natural flavonoids to inhibit the HN protein of HPIV3.

Respiratory Syncytial Virus, Human Metapneumovirus, and Parainfluenza Virus Infections in Lung Transplant Recipients: A Systematic Review of Outcomes and Treatment Strategies.

BACKGROUND: Respiratory syncytial virus (RSV), parainfluenza virus (PIV), and human metapneumovirus (hMPV) are increasingly associated with chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTR). This systematic review primarily aimed to assess outcomes of RSV/PIV/hMPV infections in LTR and secondarily to assess evidence regarding the efficacy of ribavirin. METHODS: Relevant databases were queried and study outcomes extracted using a standardized method and summarized. RESULTS: Nineteen retrospective and 12 prospective studies were included (total 1060 cases). Pooled 30-day mortality was low (0-3%), but CLAD progression 180-360 days postinfection was substantial (pooled incidences 19-24%) and probably associated with severe infection. Ribavirin trended toward effectiveness for CLAD prevention in exploratory meta-analysis (odds ratio [OR] 0.61, [0.27-1.18]), although results were highly variable between studies. CONCLUSIONS: RSV/PIV/hMPV infection was followed by a high CLAD incidence. Treatment options, including ribavirin, are limited. There is an urgent need for high-quality studies to provide better treatment options for these infections.

Interactions between the Nucleoprotein and the Phosphoprotein of Pneumoviruses: Structural Insight for Rational Design of Antivirals.

Pneumoviruses include pathogenic human and animal viruses, the most known and studied being the human respiratory syncytial virus (hRSV) and the metapneumovirus (hMPV), which are the major cause of severe acute respiratory tract illness in young children worldwide, and main pathogens infecting elderly and immune-compromised people. The transcription and replication of these viruses take place in specific cytoplasmic inclusions called inclusion bodies (IBs). These activities depend on viral polymerase L, associated with its cofactor phosphoprotein P, for the recognition of the viral RNA genome encapsidated by the nucleoprotein N, forming the nucleocapsid (NC). The polymerase activities rely on diverse transient protein-protein interactions orchestrated by P playing the hub role. Among these interactions, P interacts with the NC to recruit L to the genome. The P protein also plays the role of chaperone to maintain the neosynthesized N monomeric and RNA-free (called N0) before specific encapsidation of the viral genome and antigenome. This review aims at giving an overview of recent structural information obtained for hRSV and hMPV P, N, and more specifically for P-NC and N0-P complexes that pave the way for the rational design of new antivirals against those viruses.

Highly Potent Host-Specific Small-Molecule Inhibitor of Paramyxovirus and Pneumovirus Replication with High Resistance Barrier.

Multiple enveloped RNA viruses of the family Paramyxoviridae and Pneumoviridae, like measles virus (MeV), Nipah virus (NiV), canine distemper virus (CDV), or respiratory syncytial virus (RSV), are of high clinical relevance. Each year a huge number of lives are lost as a result of these viral infections. Worldwide, MeV infection alone is responsible for over a hundred thousand deaths each year despite available vaccine. Therefore, there is an urgent need for treatment options to counteract these viral infections. The development of antiviral drugs in general stands as a huge challenge due to the rapid emergence of viral escape mutants. Here, we disclose the discovery of a small-molecule antiviral, compound 1 (ZHAWOC9045), active against several pneumo-/paramyxoviruses, including MeV, NiV, CDV, RSV, and parainfluenza virus type 5 (PIV-5). A series of mechanistic characterizations revealed that compound 1 targets a host factor which is indispensable for viral genome replication. Drug resistance profiling against a paramyxovirus model (CDV) demonstrated no detectable adaptation despite prolonged time of investigation, thereby mitigating the rapid emergence of escape variants. Furthermore, a thorough structure-activity relationship analysis of compound 1 led to the invention of 100-times-more potent-derivatives, e.g., compound 2 (ZHAWOC21026). Collectively, we present in this study an attractive host-directed pneumoviral/paramyxoviral replication inhibitor with potential therapeutic application. IMPORTANCE Measles virus, respiratory syncytial virus, canine distemper virus, and Nipah virus are some of the clinically significant RNA viruses that threaten substantial number of lives each year. Limited to no availability of treatment options for these viral infections makes it arduous to handle the outbreaks. This highlights the major importance of developing antivirals to fight not only ongoing infections but also potential future epidemics. Most of the discovered antivirals, in clinical trials currently, are virus targeted, which consequently poses the challenge of rapid emergence of escape variants. Here, we present compound 1 (ZHAWOC9045), discovered to target viral replication in a host-dependent manner, thereby exhibiting broad-spectrum activity against several members of the family Pneumo-/Paramyxoviridae. The inability of viruses to mutate against the inhibitor mitigated the critical issue of generation of escape variants. Importantly, compound 1 was successfully optimized to a highly potent variant, compound 2 (ZHAWOC21026), with a promising profile for pharmacological intervention.

Antivirals targeting paramyxovirus membrane fusion.

The Paramyxoviridae family includes enveloped single-stranded negative-sense RNA viruses such as measles, mumps, human parainfluenza, canine distemper, Hendra, and Nipah viruses, which cause a tremendous global health burden. The ability of paramyxoviral glycoproteins to merge viral and host membranes allows entry of the viral genome into host cells, as well as cell-cell fusion, an important contributor to disease progression. Recent molecular and structural advances in our understanding of the paramyxovirus membrane fusion machinery gave rise to various therapeutic approaches aiming at inhibiting viral infection, spread, and cytopathic effects. These therapeutic approaches include peptide mimics, antibodies, and small molecule inhibitors with various levels of success at inhibiting viral entry, increasing the potential of effective antiviral therapeutic development.

Platinum complexes act as shielding agents against virus infection.

We determine that the substitution-inert polynuclear platinum complex (PPC) TriplatinNC is an antiviral agent and protects cells from enterovirus 71 and human metapneumovirus infection. This protection occurs through the formation of adducts with cell-surface glycosaminoglycans. Our detailed mechanistic investigation demonstrates that TriplatinNC blocks viral entry by shielding cells from virus attack, opening new directions for metalloshielding antiviral drug development.

Screening interferon antagonists from accessory proteins encoded by P gene for immune escape of Caprine parainfluenza virus 3.

The Caprine parainfluenza virus 3 (CPIV3) is a novel Paramyxovirus that is isolated from goats suffering from respiratory diseases. Presently, the pathogenesis of CPIV3 infection has not yet been fully characterized. The Type I interferon (IFN) is a key mediator of innate antiviral responses, as many viruses have developed strategies to circumvent IFN response, whether or how CPIV3 antagonizes type I IFN antiviral effects have not yet been characterized. This study observed that CPIV3 was resistant to IFN-α treatment and antagonized IFN-α antiviral responses on MDBK and goat tracheal epithelial (GTE) cell models. Western blot analysis showed that CPIV3 infection reduced STAT1 expression and phosphorylation, which inhibited IFN-α signal transduction on GTE cells. By screening and utilizing specific monoclonal antibodies (mAbs), three CPIV3 accessory proteins C, V and D were identified during the virus infection process on the GTE cell models. Accessory proteins C and V, but not protein D, was identified to antagonize IFN-α antiviral signaling. Furthermore, accessory protein C, but not protein V, reduced the level of IFN-α driven phosphorylated STAT1 (pSTAT1), and then inhibit STAT1 signaling. Genetic variation analysis to the PIV3 accessory protein C has found two highly variable regions (VR), with VR2 (31-70th aa) being involved in for the CPIV3 accessory protein C to hijack the STAT1 signaling activation. The above data indicated that CPIV3 is capable of inhibiting IFN-α signal transduction by reducing STAT1 expression and activation, and that the accessory protein C, plays vital roles in the immune escape process.

Respiratory Virus Infections in Asthma: Research Developments and Therapeutic Advances.

In this review, we discuss the latest developments in research pertaining to virus-induced asthma exacerbations and consider recent advances in treatment options. Asthma is a chronic disease of the airways that continues to impose a substantial clinical burden worldwide. Asthma exacerbations, characterised by an acute deterioration in respiratory symptoms and airflow obstruction, are associated with significant morbidity and mortality. These episodes are most commonly triggered by respiratory virus infections. The mechanisms underlying the pathogenesis of virus-induced exacerbations have been the focus of extensive biomedical research. Developing a robust understanding of the interplay between respiratory viruses and the host immune response will be critical for developing more efficacious, targeted therapies for exacerbations. CONCLUSION: There has been significant recent progress in our understanding of the mechanisms underlying virus-induced airway inflammation in asthma and these advances will underpin the development of future clinical therapies.

Hemophilus influenzae and Parainfluenza Virus Pneumonia in a Patient with AIDS.

BACKGROUND Parainfluenza viruses (PIV) are known to cause mild respiratory tract infections in immunocompetent patients but can cause severe infections in immune-compromised patients such as transplant recipients and children with HIV. PIV infection in HIV-infected adults has rarely been reported. We report a case of PIV pneumonia in an adult with AIDS who was successfully treated with oral ribavirin. CASE REPORT A 64-year-old man with history of acquired immune deficiency syndrome (AIDS) was admitted to the hospital with shortness of breath that began 3 days before. He was in respiratory distress and required mechanical ventilation on arrival. A bronchoalveolar lavage (BAL) culture was positive for Hemophilus influenzae and a respiratory viral panel was positive for Parainfluenza virus. The patient was initially started on Cefepime and Trimethoprim- Sulfamethoxazole and later changed to Ceftriaxone based on culture results. As the patient's condition did not improve after 48 h, oral ribavirin was added to treat PIV. The patient subsequently improved and was extubated after 72 h. CONCLUSIONS Oral ribavirin can have a beneficial effect in AIDS patients who have PIV-associated pneumonia. Further investigation of the benefit of oral ribavirin in similar cases is warranted.

Structural Insight into Paramyxovirus and Pneumovirus Entry Inhibition.

Paramyxoviruses and pneumoviruses infect cells through fusion (F) protein-mediated merger of the viral envelope with target membranes. Members of these families include a range of major human and animal pathogens, such as respiratory syncytial virus (RSV), measles virus (MeV), human parainfluenza viruses (HPIVs), and highly pathogenic Nipah virus (NiV). High-resolution F protein structures in both the metastable pre- and the postfusion conformation have been solved for several members of the families and a number of F-targeting entry inhibitors have progressed to advanced development or clinical testing. However, small-molecule RSV entry inhibitors have overall disappointed in clinical trials and viral resistance developed rapidly in experimental settings and patients, raising the question of whether the available structural information may provide a path to counteract viral escape through proactive inhibitor engineering. This article will summarize current mechanistic insight into F-mediated membrane fusion and examine the contribution of structural information to the development of small-molecule F inhibitors. Implications are outlined for future drug target selection and rational drug engineering strategies.

Co-infection with SARS-CoV-2 and Human Metapneumovirus.

The novel coronavirus (now called SARS-CoV-2) initially discovered in Wuhan, China, has now become a global pandemic. We describe a patient presenting to an Emergency Department in Rhode Island on March 12, 2020 with cough and shortness of breath after a trip to Jamaica. The patient underwent nasopharyngeal swab for a respiratory pathogen panel as well as SARS-CoV-2 RT-PCR. When the respiratory pathogen panel was positive for human metapneumovirus, the patient was treated and discharged. SARS-CoV-2 RT-PCR came back positive 24 hours later. Although respiratory viral co-infection is thought to be relatively uncommon in adults, this case reflects that SARS-CoV-2 testing algorithms that exclude patients who test positive for routine viral pathogens may miss SARS-CoV-2 co-infected patients.

Respiratory syncytial virus and human metapneumovirus after allogeneic hematopoietic stem cell transplantation: Impact of the immunodeficiency scoring index, viral load, and ribavirin treatment on the outcomes.

INTRODUCTION: Respiratory viral infections are a major cause of morbidity and mortality among stem cell transplant recipients. While there is a substantial amount of information on prognostic factors and response to ribavirin therapy is available for RSV infections, this information is largely lacking for hMPV. PATIENTS AND METHODS: In total, 71 patients were included in this study: 47 patients with RSV and 24 with hMPV. Forty-one patients presented as an upper respiratory tract infection (URTI) and 30 as a primary lower respiratory tract infection (LRTI). Patients were stratified as per ISI criteria into low-, moderate-, and high-risk groups. Twenty-two patients in the URTI cohort received treatment with ribavirin (mainly oral), and 19 patients received no antiviral therapy. The decision for antiviral treatment was at the discretion of the attending physician. All 30 patients with primary LRTI and 10 patients with secondary LRTI were treated with ribavirin, 95% with the intravenous formulation. 45% of these patients received additional treatment with intravenous immunoglobulins. The viral load was assessed indirectly by using the CT value of the RT-PCR. RESULTS: In the cohort, as whole 11.5% suffered a virus-associated death, 5% in the URTI group, and 20% in the LRTI group. Sixty-day mortality was significantly higher in the ISI high-risk group (log-rank P = .05). Mortality was independent of the type of virus (P = .817). Respiratory failure with an indication for mechanical ventilation developed in 11.5%, this risk was independent of the type of virus. Progression from URTI to LRTI was observed in 24% of cases with a significantly higher risk (75%) in the ISI high group (log-rank P = .001). In the ISI high-risk group, treatment with ribavirin significantly reduced the risk of progression (log-rank P < .001). Neither the type of virus nor the viral load in the nasopharyngeal swab impacted the risk of progression (P = .529 and P = .141, respectively). The detection of co-pathogens in the BAL fluid was borderline significant for mortality (P = .07). CONCLUSIONS: We could detect no differences between RSV and hMPV with respect to progression to LRTI, risk of respiratory failure or need for mechanical ventilation and virus-associated death. The ISI index is of predictive value in hMPV patients with a high ISI score and treatment with oral ribavirin has an equivalent protective effect in RSV and hMPV patients. Treatment of LRTI with intravenous ribavirin results in a similar outcome in RSV- and hMPV-infected patients. We could not detect any benefit of adjunctive treatment with immunoglobulins in both primary and secondary LRTI. No role of viral load as an independent prognostic marker could be detected either for progression to LRTI or death.

Hijacking the Fusion Complex of Human Parainfluenza Virus as an Antiviral Strategy.

The receptor binding protein of parainfluenza virus, hemagglutinin-neuraminidase (HN), is responsible for actively triggering the viral fusion protein (F) to undergo a conformational change leading to insertion into the target cell and fusion of the virus with the target cell membrane. For proper viral entry to occur, this process must occur when HN is engaged with host cell receptors at the cell surface. It is possible to interfere with this process through premature activation of the F protein, distant from the target cell receptor. Conformational changes in the F protein and adoption of the postfusion form of the protein prior to receptor engagement of HN at the host cell membrane inactivate the virus. We previously identified small molecules that interact with HN and induce it to activate F in an untimely fashion, validating a new antiviral strategy. To obtain highly active pretriggering candidate molecules we carried out a virtual modeling screen for molecules that interact with sialic acid binding site II on HN, which we propose to be the site responsible for activating F. To directly assess the mechanism of action of one such highly effective new premature activating compound, PAC-3066, we use cryo-electron tomography on authentic intact viral particles for the first time to examine the effects of PAC-3066 treatment on the conformation of the viral F protein. We present the first direct observation of the conformational rearrangement induced in the viral F protein.IMPORTANCE Paramyxoviruses, including human parainfluenza virus type 3, are internalized into host cells by fusion between viral and target cell membranes. The receptor binding protein, hemagglutinin-neuraminidase (HN), upon binding to its cell receptor, triggers conformational changes in the fusion protein (F). This action of HN activates F to reach its fusion-competent state. Using small molecules that interact with HN, we can induce the premature activation of F and inactivate the virus. To obtain highly active pretriggering compounds, we carried out a virtual modeling screen for molecules that interact with a sialic acid binding site on HN that we propose to be the site involved in activating F. We use cryo-electron tomography of authentic intact viral particles for the first time to directly assess the mechanism of action of this treatment on the conformation of the viral F protein and present the first direct observation of the induced conformational rearrangement in the viral F protein.