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Virus Research May 2019Pneumoviruses represent a major public health burden across the world. Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV), two of the most recognizable... (Review)
Review
Pneumoviruses represent a major public health burden across the world. Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV), two of the most recognizable pediatric infectious agents, belong to this family. These viruses are enveloped with a non-segmented negative-sense RNA genome, and their replication occurs in specialized cytosolic organelles named inclusion bodies (IB). The critical role of IBs in replication of pneumoviruses has begun to be elucidated, and our current understanding suggests they are highly dynamic structures. From IBs, newly synthesized nucleocapsids are transported to assembly sites, potentially via the actin cytoskeleton, to be incorporated into nascent virions. Released virions, which generally contain one genome, can then diffuse in the extracellular environment to target new cells and reinitiate the process of infection. This is a challenging business for virions, which must face several risks including the extracellular immune responses. In addition, several recent studies suggest that successful infection may be achieved more rapidly by multiple, rather than single, genomic copies being deposited into a target cell. Interestingly, recent data indicate that pneumoviruses have several mechanisms that permit their transmission en bloc, i.e. transmission of multiple genomes at the same time. These mechanisms include the well-studied syncytia formation as well as the newly described formation of long actin-based intercellular extensions. These not only permit en bloc viral transmission, but also bypass assembly of complete virions. In this review we describe several aspects of en bloc viral transmission and how these mechanisms are reshaping our understanding of pneumovirus replication, assembly and spread.
Topics: Animals; Cell Line; Humans; Metapneumovirus; Mice; Paramyxoviridae Infections; Pneumovirus; RNA, Viral; Virion; Virus Assembly; Virus Replication
PubMed: 30844414
DOI: 10.1016/j.virusres.2019.03.002 -
Clinical and Experimental Medicine Oct 2023Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) cause a high burden of disease, particularly in children and the elderly. With the aim to add...
Multicenter epidemiological investigation and genetic characterization of respiratory syncytial virus and metapneumovirus infections in the pre-pandemic 2018-2019 season in northern and central Italy.
Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) cause a high burden of disease, particularly in children and the elderly. With the aim to add knowledge on RSV and HMPV infections in Italy, a prospective, multicenter study was conducted by eight centers of the Working Group on Respiratory Virus Infections (GLIViRe), from December 2018-April 2019. Weekly distribution and patients' demographic and clinical data were compared in 1300 RSV and 222 HMPV-positive cases. Phylogenetic analysis of the G-glycoprotein coding region was performed to characterize circulating strains. RSV positivity ranged from 6.4% in outpatients of all ages to 31.7% in hospitalized children; HMPV positivity was 4-1.2% with no age-association. RSV season peaked in February and ended in mid-April: HMPV circulation was higher when RSV decreased in early spring. RSV was more frequent in infants, whereas HMPV infected comparatively more elderly adults; despite, their clinical course was similar. RSV-B cases were two-thirds of the total and had similar clinical severity compared to RSV-A. Phylogenetic analysis showed the circulation of RSV-A ON1 variants and the predominance of RSV-B genotype BA10. HMPV genotype A2c was the prevalent one and presented insertions of different lengths in G. This first multicenter Italian report on seasonality, age-specific distribution, and clinical presentation of RSV and HMPV demonstrated their substantial disease burden in young patients but also in the elderly. These data may provide the basis for a national respiratory virus surveillance network.
Topics: Infant; Child; Adult; Humans; Aged; Metapneumovirus; Seasons; Phylogeny; Prospective Studies; Pandemics; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human
PubMed: 36522554
DOI: 10.1007/s10238-022-00973-3 -
Communications Biology Jun 2023Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in...
Respiratory syncytial virus (RSV) and human metapneumovirus (HMPV) are related RNA viruses responsible for severe respiratory infections and resulting disease in infants, elderly, and immunocompromised adults. Therapeutic small molecule inhibitors that bind to the RSV polymerase and inhibit viral replication are being developed, but their binding sites and molecular mechanisms of action remain largely unknown. Here we report a conserved allosteric inhibitory site identified on the L polymerase proteins of RSV and HMPV that can be targeted by a dual-specificity, non-nucleoside inhibitor, termed MRK-1. Cryo-EM structures of the inhibitor in complexes with truncated RSV and full-length HMPV polymerase proteins provide a structural understanding of how MRK-1 is active against both viruses. Functional analyses indicate that MRK-1 inhibits conformational changes necessary for the polymerase to engage in RNA synthesis initiation and to transition into an elongation mode. Competition studies reveal that the MRK-1 binding pocket is distinct from that of a capping inhibitor with an overlapping resistance profile, suggesting that the polymerase conformation bound by MRK-1 may be distinct from that involved in mRNA capping. These findings should facilitate optimization of dual RSV and HMPV replication inhibitors and provide insights into the molecular mechanisms underlying their polymerase activities.
Topics: Infant; Adult; Humans; Aged; Metapneumovirus; RNA-Dependent RNA Polymerase; Respiratory Syncytial Virus, Human; Respiratory Tract Infections; RNA, Messenger
PubMed: 37337079
DOI: 10.1038/s42003-023-04990-0 -
Clinical Microbiology Reviews Oct 2016Globally, as a leading agent of acute respiratory tract infections in children <5 years of age and the elderly, the human metapneumovirus (HMPV) has gained considerable... (Review)
Review
Globally, as a leading agent of acute respiratory tract infections in children <5 years of age and the elderly, the human metapneumovirus (HMPV) has gained considerable attention. As inferred from studies comparing vaccinated and experimentally infected mice, the acquired immune response elicited by this pathogen fails to efficiently clear the virus from the airways, which leads to an exaggerated inflammatory response and lung damage. Furthermore, after disease resolution, there is a poor development of T and B cell immunological memory, which is believed to promote reinfections and viral spread in the community. In this article, we discuss the molecular mechanisms that shape the interactions of HMPV with host tissues that lead to pulmonary pathology and to the development of adaptive immunity that fails to protect against natural infections by this virus.
Topics: Adaptive Immunity; Animals; Disease Models, Animal; Host-Pathogen Interactions; Humans; Metapneumovirus; Mice; Paramyxoviridae Infections; Respiratory Tract Infections
PubMed: 27413096
DOI: 10.1128/CMR.00081-15 -
Virus Research Oct 2023Human metapneumovirus (HMPV) causes respiratory tract infections among infant, elderly, and immunocompromised patients, with significant mortality. Currently no licensed...
BACKGROUND
Human metapneumovirus (HMPV) causes respiratory tract infections among infant, elderly, and immunocompromised patients, with significant mortality. Currently no licensed vaccines or therapeutic agents of HMPV exist.
METHODS
HMPV virus-like particle (VLP) was constructed by co-expressing fusion protein of HMPV and matrix 1 protein of influenza virus using the baculovirus expression. Mice were immunized with VLP with or without aluminum hydroxide (alum) adjuvant by intramuscular route respectively. Sera were determined for titers of IgG and neutralizing antibody. Splenic lymphocytes were determined by IFN-γ and IL-4 ELISPOT. Mice were challenged with HMPV, and protective efficacy was evaluated.
RESULTS
We generated HMPV VLP in baculovirus expression system. After three times immunization, IgG antibody titers induced by VLP formulated with or without alum adjuvant group were 273,066 ± 100,331 and 136,533 ± 47,269 respectively, there was no difference (p ˃ 0.05); the neutralizing antibody titers vaccinated with VLP plus with alum adjuvant (266 ± 92) were higher than those of the VLP alone group (106 ± 37). For IFN-γ, mice vaccinated with VLP with or without alum adjuvant are 151 ± 36.4 and 77.0 ± 17.1SFC/10 respectively, there was difference (p = 0.03); For IL-4, they are 261.3 ± 38.7 versus 125.67 ± 29.78SFC/10 respectively, the difference was significant (p = 0.009). After challenge, in pathological analysis, the overall lesion scores in the VLP plus with and without alum adjuvant were 3.25 and 5.6 respectively, those of control group is 8. For immunohistochemical analyses, the average optical density of the lungs in the VLP immunized group containing adjuvant (9.07 ± 1.74) was lower than that in the VLP group without adjuvant (12.83 ± 2.31, p = 0.14).
CONCLUSIONS
This is the first study to demonstrate that HMPV VLP was successfully prepared in the baculovirus expression system. HMPV VLP could induce specific humoral and cellular immune responses as well as protective efficacy, and aluminum hydroxide may be an effective adjuvant in mice.
Topics: Humans; Mice; Animals; Aged; Metapneumovirus; Antibodies, Viral; Aluminum Hydroxide; Baculoviridae; Interleukin-4; Antibodies, Neutralizing; Adjuvants, Immunologic; Vaccines, Virus-Like Particle; Mice, Inbred BALB C
PubMed: 37657510
DOI: 10.1016/j.virusres.2023.199215 -
Clinical Microbiology Reviews Jul 2006Since the discovery of human metapneumovirus (hMPV) in 2001, the virus has been identified worldwide. hMPV is a common respiratory pathogen, particularly in infants and... (Review)
Review
Since the discovery of human metapneumovirus (hMPV) in 2001, the virus has been identified worldwide. hMPV is a common respiratory pathogen, particularly in infants and young children. The virus is associated with both upper and lower respiratory tract infections and may be a trigger for asthma. At least two major genotypes of hMPV circulate during community outbreaks. Whether these genotypes represent distinct serotypes remains controversial. The major challenges faced by the medical and scientific communities are the understanding of the pathogenesis of hMPV disease and the development of a safe and effective vaccine to protect against infection and disease caused by this newly recognized respiratory virus.
Topics: Child, Preschool; Humans; Metapneumovirus; Molecular Epidemiology; Paramyxoviridae Infections; Respiratory Tract Infections; Seasons
PubMed: 16847085
DOI: 10.1128/CMR.00014-06 -
PloS One 2014Four avian metapneumovirus (AMPV) subgroups (A-D) have been reported previously based on genetic and antigenic differences. However, until now full length sequences of...
Molecular comparisons of full length metapneumovirus (MPV) genomes, including newly determined French AMPV-C and -D isolates, further supports possible subclassification within the MPV Genus.
Four avian metapneumovirus (AMPV) subgroups (A-D) have been reported previously based on genetic and antigenic differences. However, until now full length sequences of the only known isolates of European subgroup C and subgroup D viruses (duck and turkey origin, respectively) have been unavailable. These full length sequences were determined and compared with other full length AMPV and human metapneumoviruses (HMPV) sequences reported previously, using phylogenetics, comparisons of nucleic and amino acid sequences and study of codon usage bias. Results confirmed that subgroup C viruses were more closely related to HMPV than they were to the other AMPV subgroups in the study. This was consistent with previous findings using partial genome sequences. Closer relationships between AMPV-A, B and D were also evident throughout the majority of results. Three metapneumovirus "clusters" HMPV, AMPV-C and AMPV-A, B and D were further supported by codon bias and phylogenetics. The data presented here together with those of previous studies describing antigenic relationships also between AMPV-A, B and D and between AMPV-C and HMPV may call for a subclassification of metapneumoviruses similar to that used for avian paramyxoviruses, grouping AMPV-A, B and D as type I metapneumoviruses and AMPV-C and HMPV as type II.
Topics: Amino Acid Sequence; Base Sequence; Codon; Genome, Viral; Metapneumovirus; Molecular Sequence Data; Phylogeny; Sequence Alignment
PubMed: 25036224
DOI: 10.1371/journal.pone.0102740 -
MBio Jun 2022Human metapneumovirus (HMPV) inclusion bodies (IBs) are dynamic structures required for efficient viral replication and transcription. The minimum components needed to...
Human metapneumovirus (HMPV) inclusion bodies (IBs) are dynamic structures required for efficient viral replication and transcription. The minimum components needed to form IB-like structures in cells are the nucleoprotein (N) and the tetrameric phosphoprotein (P). HMPV P binds to the following two versions of the N protein in infected cells: N-terminal P residues interact with monomeric N (N) to maintain a pool of protein to encapsidate new RNA and C-terminal P residues interact with oligomeric, RNA-bound N (N-RNA). Recent work on other negative-strand viruses has suggested that IBs are, at least in part, liquid-like phase-separated membraneless organelles. Here, HMPV IBs in infected or transfected cells were shown to possess liquid organelle properties, such as fusion and fission. Recombinant versions of HMPV N and P proteins were purified to analyze the interactions required to drive phase separation . Purified HMPV P was shown to form liquid droplets in isolation. This observation is distinct from other viral systems that also form IBs. Partial removal of nucleic acid from purified P altered phase-separation dynamics, suggesting that nucleic acid interactions play a role in IB formation. HMPV P also recruits monomeric N (N-P) and N-RNA to droplets . These findings suggest that HMPV P may also act as a scaffold protein to mediate multivalent interactions with monomeric and oligomeric N, as well as RNA, to promote phase separation of IBs. Together, these findings highlight an additional layer of regulation in HMPV replication by the viral P and N proteins. Human metapneumovirus (HMPV) is a leading cause of respiratory disease among children, immunocompromised individuals, and the elderly. Currently, no vaccines or antivirals are available for the treatment of HMPV infections. Cytoplasmic inclusion bodies (IBs), where HMPV replication and transcription occur, represent a promising target for the development of novel antivirals. The HMPV nucleoprotein (N) and phosphoprotein (P) are the minimal components needed for IB formation in eukaryotic cells. However, interactions that regulate the formation of these dynamic structures are poorly understood. Here, we showed that HMPV IBs possess the properties of liquid organelles and that purified HMPV P phase separates independently . Our work suggests that HMPV P phase-separation dynamics are altered by nucleic acid. We provide strong evidence that, unlike results reported from other viral systems, HMPV P alone can serve as a scaffold for multivalent interactions with monomeric (N) and oligomeric (N-RNA) HMPV N for IB formation.
Topics: Humans; Antiviral Agents; Metapneumovirus; Nucleic Acids; Nucleoproteins; Phosphoproteins; RNA; Virus Replication; Inclusion Bodies, Viral
PubMed: 35536005
DOI: 10.1128/mbio.01099-22 -
Viruses Jun 2013Lung dendritic cells (DC) play a fundamental role in sensing invading pathogens, as well as in the control of tolerogenic responses in the respiratory tract. Their... (Review)
Review
Lung dendritic cells (DC) play a fundamental role in sensing invading pathogens, as well as in the control of tolerogenic responses in the respiratory tract. Their strategic localization at the site of pathogen entry makes them particularly susceptible to initial viral invasion. Human respiratory syncytial virus (hRSV) and human metapneumovirus (hMPV) belong to the Paramyxoviridae family, within the Pneumovirus and Metapneumovirus genera, respectively. hRSV and hMPV are significant human respiratory pathogens that cause similar clinical manifestations and affect many of the same subpopulations. However, they differentially activate the host immune response, including DC, which represents a fundamental link between the innate and adaptive immune response. In this review, the role of DC in the immune response against hRSV and hMPV infections, as well as the inhibitory effects of these paramyxoviruses on the DC immunity will be discussed.
Topics: Dendritic Cells; Humans; Metapneumovirus; Paramyxoviridae Infections; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human
PubMed: 23787776
DOI: 10.3390/v5061553 -
Infectious Disease Clinics of North... Sep 2017Lower respiratory tract infection is a leading cause of death in the United States. Advances in diagnostic testing have improved our ability to detect pathogens. Viral... (Review)
Review
Lower respiratory tract infection is a leading cause of death in the United States. Advances in diagnostic testing have improved our ability to detect pathogens. Viral pathogens are important causal pathogens in immunocompetent patients. As the number of elderly adults and those with chronic medical conditions increases, the burden of viral respiratory infections will increase. Clinicians must be familiar with the characteristics of rhinovirus, human adenoviruses, respiratory syncytial virus, and human metapneumovirus. Major challenges include distinguishing true infection from asymptomatic carriage and characterizing patients admitted with severe lower respiratory tract infection who do not have a causative pathogen identified.
Topics: Adult; Aged; Community-Acquired Infections; Female; Humans; Immunocompetence; Immunocompromised Host; Infant; Male; Metapneumovirus; Molecular Diagnostic Techniques; Pneumonia, Viral; Respiratory Syncytial Viruses; Respiratory Tract Infections; Rhinovirus; United States
PubMed: 28687214
DOI: 10.1016/j.idc.2017.05.004