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Otomaru H, Nguyen HAT, Vo HM, Toizumi M, Le MN, Mizuta K, Moriuchi H, Bui MX, Dang DA, Yoshida LM. A decade of human metapneumovirus in hospitalized children with acute respiratory infection: molecular epidemiology in central Vietnam, 2007-2017. Sci Rep 2023; 13:15757. [PMID: 37735242 PMCID: PMC10514255 DOI: 10.1038/s41598-023-42692-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 09/13/2023] [Indexed: 09/23/2023] Open
Abstract
Human metapneumovirus (hMPV) can cause severe acute respiratory infection (ARI). We aimed to clarify the clinical and molecular epidemiological features of hMPV. We conducted an ARI surveillance targeting hospitalized children aged 1 month to 14 years in Nha Trang, Vietnam. Nasopharyngeal swabs were tested for respiratory viruses with PCR. We described the clinical characteristics of hMPV patients in comparison with those with respiratory syncytial virus (RSV) and those with neither RSV nor hMPV, and among different hMPV genotypes. Among 8822 patients, 278 (3.2%) were hMPV positive, with a median age of 21.0 months (interquartile range: 12.7-32.5). Among single virus-positive patients, hMPV cases were older than patients with RSV (p < 0.001) and without RSV (p = 0.003). The proportions of clinical pneumonia and wheezing in hMPV patients resembled those in RSV patients but were higher than in non-RSV non-hMPV patients. Seventy percent (n = 195) were genotyped (A2b: n = 40, 20.5%; A2c: n = 99, 50.8%; B1: n = 37, 19%; and B2: n = 19, 9.7%). The wheezing frequency was higher in A2b patients (76.7%) than in those with other genotypes (p = 0.033). In conclusion, we found a moderate variation in clinical features among hMPV patients with various genotypes. No seasonality was observed, and the multiple genotype co-circulation was evident.
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Affiliation(s)
- Hirono Otomaru
- Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Hien Anh Thi Nguyen
- Department of Bacteriology, National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Hien Minh Vo
- Department of Pediatrics, Khanh Hoa General Hospital, Nha Trang, Vietnam
| | - Michiko Toizumi
- Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Minh Nhat Le
- Antimicrobial Resistance Research Centre, National Institute of Infectious Disease (NIID), Sinjuku, Japan
- Tay Nguyen Institute of Science Research, Vietnam Academy of Science and Technology (VAST), Da Lat, Vietnam
| | - Katsumi Mizuta
- Yamagata Prefectural Institute of Public Health, Yamagata, Japan
| | - Hiroyuki Moriuchi
- Department of Pediatrics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Minh Xuan Bui
- Khanh Hoa Health Service Department, Nha Trang, Vietnam
| | - Duc Anh Dang
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Lay-Myint Yoshida
- Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
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Hacker K, Kuan G, Vydiswaran N, Chowell‐Puente G, Patel M, Sanchez N, Lopez R, Ojeda S, Lopez B, Mousa J, Maier HE, Balmaseda A, Gordon A. Pediatric burden and seasonality of human metapneumovirus over 5 years in Managua, Nicaragua. Influenza Other Respir Viruses 2022; 16:1112-1121. [PMID: 35965382 PMCID: PMC9530515 DOI: 10.1111/irv.13034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/26/2022] [Accepted: 07/30/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Human metapneumovirus (hMPV) is an important cause of pediatric respiratory infection. We leveraged the Nicaraguan Pediatric Influenza Cohort Study (NPICS) to assess the burden and seasonality of symptomatic hMPV infection in children. METHODS NPICS is an ongoing prospective study of children in Managua, Nicaragua. We assessed children for hMPV infection via real-time reverse-transcription polymerase chain reaction (RT-PCR). We used classical additive decomposition analysis to assess the temporal trends, and generalized growth models (GGMs) were used to estimate effective reproduction numbers. RESULTS From 2011 to 2016, there were 564 hMPV symptomatic infections, yielding an incidence rate of 5.74 cases per 100 person-years (95% CI 5.3, 6.2). Children experienced 3509 acute lower respiratory infections (ALRIs), of which 160 (4.6%) were associated with hMPV infection. Children under the age of one had 55% of all symptomatic hMPV infections (62/112) develop into hMPV-associated ALRIs and were five times as likely as children over one to have an hMPV-associated ALRI (rate ratio 5.5 95% CI 4.1, 7.4 p < 0.001). Additionally, symptomatic reinfection with hMPV was common. In total, 87 (15%) of all observed symptomatic infections were detected reinfections. The seasonality of symptomatic hMPV outbreaks varied considerably. From 2011 to 2016, four epidemic periods were observed, following a biennial seasonal pattern. The mean ascending phase of the epidemic periods were 7.7 weeks, with an overall mean estimated reproductive number of 1.2 (95% CI 1.1, 1.4). CONCLUSIONS Symptomatic hMPV infection was associated with substantial burden among children in the first year of life. Timing and frequency of symptomatic hMPV incidence followed biennial patterns.
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Affiliation(s)
- Kathryn Hacker
- School of Public Health, Department of EpidemiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Guillermina Kuan
- Sustainable Sciences InstituteManaguaNicaragua
- Centro de Salud Sócrates Flores VivasMinistry of HealthManaguaNicaragua
| | - Nivea Vydiswaran
- School of Public Health, Department of EpidemiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Gerardo Chowell‐Puente
- School of Public Health, Department of Population Health SciencesGeorgia State UniversityAtlantaGeorgiaUSA
| | - Mayuri Patel
- School of Public Health, Department of EpidemiologyUniversity of MichiganAnn ArborMichiganUSA
| | | | - Roger Lopez
- Sustainable Sciences InstituteManaguaNicaragua
- Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y ReferenciaMinistry of HealthManaguaNicaragua
| | | | | | - Jarrod Mousa
- College of Veterinary Medicine, Center for Vaccines and ImmunologyUniversity of GeorgiaAthensGeorgiaUSA
- College of Veterinary Medicine, Department of Infectious DiseasesUniversity of GeorgiaAthensGeorgiaUSA
| | - Hannah E. Maier
- School of Public Health, Department of EpidemiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Angel Balmaseda
- Sustainable Sciences InstituteManaguaNicaragua
- Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y ReferenciaMinistry of HealthManaguaNicaragua
| | - Aubree Gordon
- School of Public Health, Department of EpidemiologyUniversity of MichiganAnn ArborMichiganUSA
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Yajima T, Takahashi H, Kimura N, Sato K, Jingu D, Ubukata S, Shoji M, Watanabe H, Kodama PEN, Nishimura H. Comparison of sputum specimens and nasopharyngeal swab specimens for diagnosis of acute human metapneumovirus-related lower respiratory tract infections in adults. J Clin Virol 2022; 154:105238. [PMID: 35907395 DOI: 10.1016/j.jcv.2022.105238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/02/2022] [Accepted: 07/06/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND To detect human metapneumovirus, tests besides reverse transcription-polymerase chain reaction (RT-PCR) on nasopharyngeal swab specimens are less accessible. Immunochromatography assays are rapid and simple without the need of any special equipment but sometimes are insufficiently sensitive. This study describes the usefulness of immunochromatography assays to detect human metapneumovirus in adult patients with human metapneumovirus-related acute lower respiratory tract infection using sputum specimens. METHODS This prospective single-center study enrolled adults and adolescents aged ≥16 years with signs and symptoms of an acute respiratory illness who were diagnosed with acute lower respiratory tract infection. The presence of human metapneumovirus infection was confirmed by seroconversion. Immunochromatography assays and real-time RT-PCR were performed to compare the efficacy of nasopharyngeal swab specimens and sputum specimens. Comparative results were obtained via McNemar's test. RESULTS Overall, 337 patients were recruited in this study; 63 (18.7%) patients were seroconverted. Sputum specimens showed significantly higher positivity rates than nasopharyngeal swab specimens with both immunochromatography assays (p = 0.0008) and real-time RT-PCR (p = 0.014). Among 29 patients with pneumonia who had concordant positive real-time RT-PCR results for both nasopharyngeal swab specimens and sputum specimens, 21 (72.4%) had a higher viral load in the sputum specimens. CONCLUSIONS Sputum specimens are more useful in detecting human metapneumovirus than nasopharyngeal swab specimens in adult patients with acute lower respiratory tract infection.
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Affiliation(s)
- Takehiro Yajima
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan; Division of Infectious Diseases, International Research Institute of Disaster Science, Tohoku University Graduate School of Medicine, Tohoku Medical Megabank Organization, Sendai, Japan; Clinical Research Division, Virus Research Center, National Hospital Organization Sendai Medical Center, Sendai, Japan
| | - Hiroshi Takahashi
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan.
| | - Nozomu Kimura
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Kosuke Sato
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Daisuke Jingu
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Satoshi Ubukata
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Makoto Shoji
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Hiroshi Watanabe
- Department of Respiratory Medicine, Saka General Hospital, Shiogama, Japan
| | - Prof Eiichi N Kodama
- Division of Infectious Diseases, International Research Institute of Disaster Science, Tohoku University Graduate School of Medicine, Tohoku Medical Megabank Organization, Sendai, Japan
| | - Hidekazu Nishimura
- Clinical Research Division, Virus Research Center, National Hospital Organization Sendai Medical Center, Sendai, Japan
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Miranda-Katz M, Erickson JJ, Lan J, Ecker A, Zhang Y, Joyce S, Williams JV. Novel HLA-B7-restricted human metapneumovirus epitopes enhance viral clearance in mice and are recognized by human CD8 + T cells. Sci Rep 2021; 11:20769. [PMID: 34675220 PMCID: PMC8531189 DOI: 10.1038/s41598-021-00023-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 10/05/2021] [Indexed: 11/09/2022] Open
Abstract
Human metapneumovirus (HMPV) is a leading cause of acute lower respiratory tract illness in children and adults. Repeated infections are common and can be severe in young, elderly, and immunocompromised persons due to short-lived protective humoral immunity. In turn, few protective T cell epitopes have been identified in humans. Thus, we infected transgenic mice expressing the common human HLA MHC-I allele B*07:02 (HLA-B7) with HMPV and screened a robust library of overlapping and computationally predicted HLA-B7 binding peptides. Six HLA-B7-restricted CD8+ T cell epitopes were identified using ELISPOT screening in the F, M, and N proteins, with M195-203 (M195) eliciting the strongest responses. MHC-tetramer flow cytometric staining confirmed HLA-B7 epitope-specific CD8+ T cells migrated to lungs and spleen of HMPV-immune mice. Immunization with pooled HLA-B7-restricted peptides reduced viral titer and protected mice from virulent infection. Finally, we confirmed that CD8+ T cells from HLA-B7 positive humans also recognize the identified epitopes. These results enable identification of HMPV-specific CD8+ T cells in humans and help to inform future HMPV vaccine design.
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Affiliation(s)
- Margot Miranda-Katz
- Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Ave, Rangos 9122, Pittsburgh, PA, 15224, USA
| | - John J Erickson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, USA
| | - Jie Lan
- Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Ave, Rangos 9122, Pittsburgh, PA, 15224, USA
| | - Alwyn Ecker
- Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Ave, Rangos 9122, Pittsburgh, PA, 15224, USA
| | - Yu Zhang
- Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Ave, Rangos 9122, Pittsburgh, PA, 15224, USA
| | - Sebastian Joyce
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, USA
- Vanderbilt Institute for Infection, Immunity, and Inflammation (VI4), Nashville, TN, 37232, USA
| | - John V Williams
- Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Ave, Rangos 9122, Pittsburgh, PA, 15224, USA.
- Institute for Infection, Inflammation, and Immunity in Children (i4Kids), Pittsburgh, PA, 15224, USA.
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Huang JM, Wang SY, Lai MR, Tseng YK, Chi YH, Huang LM. Development of a respiratory syncytial virus vaccine using human hepatitis B core-based virus-like particles to induce mucosal immunity. Vaccine 2021; 39:3259-3269. [PMID: 33972124 DOI: 10.1016/j.vaccine.2021.04.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/21/2021] [Accepted: 04/19/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Respiratory syncytial virus (RSV) is an important viral pathogen responsible for severe infection of the lower respiratory tract in children under the age of 5 years. No vaccines against RSV are currently in clinical use. Vaccine-associated enhanced respiratory disease (ERD) caused by excess Th2 type responses was observed in a clinical trial of formalin-inactivated RSV (FI-RSV) in antigen-naïve infants. Thus, inducing a balanced immune response is a crucial issue in the development of an RSV vaccine. METHODS In this study, we constructed, expressed, and purified a recombinant RSV vaccine candidate (i.e., HRØ24) containing the two heptad repeat regions and the antigenic sites Ø, II, and IV of the RSV F protein. The RSV vaccine candidate was intranasally administrated to BALB/c and C57BL/6 mice in combination with virus-like particles (VLPs) derived from the core protein of the hepatitis B virus (HBc). Mucosal immunity to HRØ24 was then assessed. RESULTS Intranasal administration of HBc VLPs in combination with HRØ24 induced serum IgGs against HRØ24 as well as lung HRØ24-specific sIgAs in both C57BL/6 and BALB/c mouse models. The secretion of IFN-γ from splenocyte re-stimulation and an elevated ratio of serum IgG2a to IgG1 indicated that the immune response induced by the HBc VLPs/HRØ24 mixture was Th1-biased. Weight loss of <5% and no to low eosinophil infiltration was observed in histological analysis of the lung following a challenge with the RSV A2 strain. These results suggest that the HBc VLPs/HRØ24 combination conferred substantial partial protection against RSV-induced illness in mice. CONCLUSIONS Long-term immunity to RSV-induced illness was achieved via intranasal vaccination using a mixture of HBc VLPs and HRØ24 in mouse models.
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Affiliation(s)
- Jen-Min Huang
- Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shih-Yun Wang
- Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Mei-Ru Lai
- Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yu-Kai Tseng
- Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ya-Hui Chi
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan.
| | - Li-Min Huang
- Department of Pediatrics, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan.
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Karimata Y, Kinjo T, Parrott G, Uehara A, Nabeya D, Haranaga S, Higa F, Tateyama M, Miyagawa K, Kishaba T, Otani K, Okamoto M, Nishimura H, Fujita J. Clinical Features of Human Metapneumovirus Pneumonia in Non-Immunocompromised Patients: An Investigation of Three Long-Term Care Facility Outbreaks. J Infect Dis 2019; 218:868-875. [PMID: 29733351 PMCID: PMC7107412 DOI: 10.1093/infdis/jiy261] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/01/2018] [Indexed: 11/25/2022] Open
Abstract
Background Several studies have reported outbreaks due to human metapneumovirus (hMPV) in long-term care facilities (LTCF) for the elderly. However, most of these reports are epidemiological studies and do not investigate the clinical features of hMPV pneumonia. Methods Three independent outbreaks of hMPV occurred at separate LTCF for intellectually challenged and elderly residents. A retrospective evaluation of hMPV pneumonia and its clinical and radiological features was conducted using available medical records and data. Results In 105 hMPV infections, 49% of patients developed pneumonia. The median age of pneumonia cases was significantly higher than non-pneumonia cases (P < .001). Clinical manifestations of hMPV pneumonia included high fever, wheezing in 43%, and respiratory failure in 31% of patients. An elevated number of white blood cells as well as increased levels of C-reactive protein, creatine phosphokinase, and both aspartate and alanine transaminases was also observed among pneumonia cases. Evaluation of chest imaging revealed proximal bronchial wall thickenings radiating outward from the hilum in most patients. Conclusions The aforementioned characteristics should be considered as representative of hMPV pneumonia. Patients presenting with these features should have laboratory testing performed for prompt diagnosis.
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Affiliation(s)
- Yosuke Karimata
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Takeshi Kinjo
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Gretchen Parrott
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Ayako Uehara
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Daijiro Nabeya
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Shusaku Haranaga
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Futoshi Higa
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Masao Tateyama
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Keiko Miyagawa
- Personnel Health Management Center, Department of General Affairs, Okinawa Prefectural Government, Japan
| | - Tomoo Kishaba
- Department of Respiratory Medicine, Okinawa Chubu Hospital, Japan
| | - Kanako Otani
- Virus Research Center, Sendai Medical Center, National Hospital Organization, Miyagi, Japan.,Department of Virology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Michiko Okamoto
- Department of Virology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Sendai Medical Center, National Hospital Organization, Miyagi, Japan
| | - Jiro Fujita
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
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Abstract
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.
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Hastings AK, Gilchuk P, Joyce S, Williams JV. Novel HLA-A2-restricted human metapneumovirus epitopes reduce viral titers in mice and are recognized by human T cells. Vaccine 2016; 34:2663-70. [PMID: 27105560 DOI: 10.1016/j.vaccine.2016.04.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 11/25/2022]
Abstract
Human metapneumovirus (HMPV) is a major cause of morbidity and mortality from acute lower respiratory tract illness, with most individuals seropositive by age five. Despite the presence of neutralizing antibodies, secondary infections are common and can be severe in young, elderly, and immunocompromised persons. Preclinical vaccine studies for HMPV have suggested a need for a balanced antibody and T cell immune response to enhance protection and avoid lung immunopathology. We infected transgenic mice expressing human HLA-A*0201 with HMPV and used ELISPOT to screen overlapping and predicted epitope peptides. We identified six novel HLA-A2 restricted CD8(+) T cell (TCD8) epitopes, with M39-47 (M39) immunodominant. Tetramer staining detected M39-specific TCD8 in lungs and spleen of HMPV-immune mice. Immunization with adjuvant-formulated M39 peptide reduced lung virus titers upon challenge. Finally, we show that TCD8 from HLA-A*0201 positive humans recognize M39 by IFNγ ELISPOT and tetramer staining. These results will facilitate HMPV vaccine development and human studies.
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Affiliation(s)
- Andrew K Hastings
- Department of Pathology, Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Pavlo Gilchuk
- Department of Pathology, Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Sebastian Joyce
- Department of Pathology, Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Veterans Administration Tennessee Valley Healthcare System, Nashville, TN 37332, USA
| | - John V Williams
- Department of Pediatrics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center, USA.
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Abstract
Human metapneumovirus (HMPV), a paramyxovirus identified in 2001, is a leading cause of respiratory tract infections in both children and adults. Seroprevalence studies demonstrate that the primary infection occurs before the age of 5 years, and humans are reinfected throughout life. The four subgroups of HMPV occur with year-to-year variability, and infection with one subgroup confers some serologic cross-protection. Experimental vaccines elicit a humoral response in both animal and human models and have been used to identify antigenic determinants. The main target of protective antibodies is the fusion (F) protein, although many of the remaining eight proteins are immunogenic. Monoclonal antibodies (mAbs) targeting the F protein are both protective and therapeutic in animal models. Most recently, the identification of broadly neutralizing antibodies against HMPV and respiratory syncytial virus demonstrates that common epitopes are present between the two viruses. Broadly neutralizing mAbs have significant clinical implications for prophylaxis and treatment of high-risk hosts as well as vaccine development.
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11
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New Approaches for Immunization and Therapy against Human Metapneumovirus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:858-66. [PMID: 26063237 DOI: 10.1128/cvi.00230-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Human metapneumovirus (HMPV) is a paramyxovirus discovered in 2001 in the Netherlands. Studies have identified HMPV as an important causative agent of acute respiratory disease in infants, the elderly, and immunocompromised individuals. Clinical signs of infection range from mild upper respiratory illness to more serious lower respiratory illness, including bronchiolitis and pneumonia. There are currently no licensed therapeutics or vaccines against HMPV. However, several research groups have tested vaccine candidates and monoclonal antibodies in various animal models. Several of these approaches have shown promise in animal models. This minireview summarizes the current therapies used to treat HMPV infection as well as different approaches for immunization.
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12
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Habibi MS, Jozwik A, Makris S, Dunning J, Paras A, DeVincenzo JP, de Haan CAM, Wrammert J, Openshaw PJM, Chiu C. Impaired Antibody-mediated Protection and Defective IgA B-Cell Memory in Experimental Infection of Adults with Respiratory Syncytial Virus. Am J Respir Crit Care Med 2015; 191:1040-9. [PMID: 25730467 PMCID: PMC4435460 DOI: 10.1164/rccm.201412-2256oc] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/25/2015] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Despite relative antigenic stability, respiratory syncytial virus (RSV) reinfects throughout life. After more than 40 years of research, no effective human vaccine exists and correlates of protection remain poorly defined. Most current vaccine candidates seek to induce high levels of RSV-specific serum neutralizing antibodies, which are associated with reduced RSV-related hospitalization rates in observational studies but may not actually prevent infection. OBJECTIVES To characterize correlates of protection from infection and the generation of RSV-specific humoral memory to promote effective vaccine development. METHODS We inoculated 61 healthy adults with live RSV and studied protection from infection by serum and mucosal antibody. We analyzed RSV-specific peripheral blood plasmablast and memory B-cell frequencies and antibody longevity. MEASUREMENTS AND MAIN RESULTS Despite moderately high levels of preexisting serum antibody, 34 (56%) became infected, of whom 23 (68%) developed symptomatic colds. Prior RSV-specific nasal IgA correlated significantly more strongly with protection from polymerase chain reaction-confirmed infection than serum neutralizing antibody. Increases in virus-specific antibody titers were variable and transient in infected subjects but correlated with plasmablasts that peaked around Day 10. During convalescence, only IgG (and no IgA) RSV-specific memory B cells were detectable in peripheral blood. This contrasted with natural influenza infection, in which virus-specific IgA memory B cells were readily recovered. CONCLUSIONS This observed specific defect in IgA memory may partly explain the ability of RSV to cause recurrent symptomatic infections. If so, vaccines able to induce durable RSV-specific IgA responses may be more protective than those generating systemic antibody alone.
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Affiliation(s)
| | - Agnieszka Jozwik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Spyridon Makris
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jake Dunning
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Allan Paras
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - John P. DeVincenzo
- Department of Pediatrics, University of Tennessee Health Sciences Center, Memphis, Tennessee
| | - Cornelis A. M. de Haan
- Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands; and
| | - Jens Wrammert
- Department of Pediatric Infectious Disease and
- Department of Hematology and Oncology, Emory University School of Medicine, Atlanta, Georgia
| | - Peter J. M. Openshaw
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Christopher Chiu
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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Yang Z, Suzuki A, Watanabe O, Okamoto M, Ohmi A, Huang W, Nishimura H. Outbreak of human metapneumovirus infection in a severe motor-and-intellectual disabilities ward in Japan. Jpn J Infect Dis 2015; 67:318-21. [PMID: 25056083 DOI: 10.7883/yoken.67.318] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Zifeng Yang
- Clinical Virology Division, State Key Laboratory of Respiratory Disease, the First Affiliated Hospital of Guangzhou Medical University
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Role of type I interferon signaling in human metapneumovirus pathogenesis and control of viral replication. J Virol 2015; 89:4405-20. [PMID: 25653440 DOI: 10.1128/jvi.03275-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Type I IFN signaling, which is initiated through activation of the alpha interferon receptor (IFNAR), regulates the expression of proteins that are crucial contributors to immune responses. Paramyxoviruses, including human metapneumovirus (HMPV), have evolved mechanisms to inhibit IFNAR signaling, but the specific contribution of IFNAR signaling to the control of HMPV replication, pathogenesis, and adaptive immunity is unknown. We used IFNAR-deficient (IFNAR(-/-)) mice to assess the effect of IFNAR signaling on HMPV replication and the CD8(+) T cell response. HMPV-infected IFNAR(-/-) mice had a higher peak of early viral replication but cleared the virus with kinetics similar to those of wild-type (WT) mice. However, IFNAR(-/-) mice infected with HMPV displayed less airway dysfunction and lung inflammation. CD8(+) T cells of IFNAR(-/-) mice after HMPV infection expressed levels of the inhibitory receptor programmed death 1 (PD-1) similar to those of WT mice. However, despite lower expression of inhibitory programmed death ligand 1 (PD-L1), HMPV-specific CD8(+) T cells of IFNAR(-/-) mice were more functionally impaired than those of WT mice and upregulated the inhibitory receptor Tim-3. Analysis of the antigen-presenting cell subsets in the lungs revealed that the expansion of PD-L1(low) dendritic cells (DCs), but not PD-L1(high) alveolar macrophages, was dependent on IFNAR signaling. Collectively, our results indicate a role for IFNAR signaling in the early control of HMPV replication, disease progression, and the development of an optimal adaptive immune response. Moreover, our findings suggest an IFNAR-independent mechanism of lung CD8(+) T cell impairment. IMPORTANCE Human metapneumovirus (HMPV) is a leading cause of acute respiratory illness. CD8(+) T cells are critical for clearing viral infection, yet recent evidence shows that HMPV and other respiratory viruses induce CD8(+) T cell impairment via PD-1-PD-L1 signaling. We sought to understand the role of type I interferon (IFN) in the innate and adaptive immune responses to HMPV by using a mouse model lacking IFN signaling. Although HMPV titers were higher in the absence of type I IFN, virus was nonetheless cleared and mice were less ill, indicating that type I IFN is not required to resolve HMPV infection but contributes to pathogenesis. Further, despite lower levels of the inhibitory ligand PD-L1 in mice lacking type I IFN, CD8(+) T cells were more impaired in these mice than in WT mice. Our data suggest that specific antigen-presenting cell subsets and the inhibitory receptor Tim-3 may contribute to CD8(+) T cell impairment.
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15
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Erickson JJ, Rogers MC, Hastings AK, Tollefson SJ, Williams JV. Programmed death-1 impairs secondary effector lung CD8⁺ T cells during respiratory virus reinfection. THE JOURNAL OF IMMUNOLOGY 2014; 193:5108-17. [PMID: 25339663 DOI: 10.4049/jimmunol.1302208] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Reinfections with respiratory viruses are common and cause significant clinical illness, yet precise mechanisms governing this susceptibility are ill defined. Lung Ag-specific CD8(+) T cells (T(CD8)) are impaired during acute viral lower respiratory infection by the inhibitory receptor programmed death-1 (PD-1). To determine whether PD-1 contributes to recurrent infection, we first established a model of reinfection by challenging B cell-deficient mice with human metapneumovirus (HMPV) several weeks after primary infection, and found that HMPV replicated to high titers in the lungs. A robust secondary effector lung TCD8 response was generated during reinfection, but these cells were more impaired and more highly expressed the inhibitory receptors PD-1, LAG-3, and 2B4 than primary T(CD8). In vitro blockade demonstrated that PD-1 was the dominant inhibitory receptor early after reinfection. In vivo therapeutic PD-1 blockade during HMPV reinfection restored lung T(CD8) effector functions (i.e., degranulation and cytokine production) and enhanced viral clearance. PD-1 also limited the protective efficacy of HMPV epitope-specific peptide vaccination and impaired lung T(CD8) during heterotypic influenza virus challenge infection. Our results indicate that PD-1 signaling may contribute to respiratory virus reinfection and evasion of vaccine-elicited immune responses. These results have important implications for the design of effective vaccines against respiratory viruses.
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Affiliation(s)
- John J Erickson
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232; and
| | - Meredith C Rogers
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232; and
| | - Andrew K Hastings
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232; and
| | - Sharon J Tollefson
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - John V Williams
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232; and Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232
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De Roche M, Sendi P. The many faces of a lung virus. JMM Case Rep 2014. [DOI: 10.1099/jmmcr.0.001925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Mirjam De Roche
- Department of Infectious Diseases, University Hospital of Bern and University of Bern, Switzerland
| | - Parham Sendi
- Department of Infectious Diseases, University Hospital of Bern and University of Bern, Switzerland
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17
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Human metapneumovirus virus-like particles induce protective B and T cell responses in a mouse model. J Virol 2014; 88:6368-79. [PMID: 24672031 DOI: 10.1128/jvi.00332-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Human metapneumovirus (HMPV) is a leading cause of respiratory disease in infants, children, and the elderly worldwide, yet no licensed vaccines exist. Live-attenuated vaccines present safety challenges, and protein subunit vaccines induce primarily antibody responses. Virus-like particles (VLPs) are an attractive alternative vaccine approach because of reduced safety concerns compared with live vaccines. We generated HMPV VLPs by expressing viral proteins in suspension-adapted human embryonic kidney epithelial (293-F) cells and found that the viral matrix (M) and fusion (F) proteins were sufficient to form VLPs. We previously reported that the VLPs resemble virus morphology and incorporate fusion-competent F protein (R. G. Cox, S. B. Livesay, M. Johnson, M. D. Ohi, and J. V. Williams, J. Virol. 86:12148-12160, 2012), which we hypothesized would elicit F-specific antibody and T cell responses. In this study, we tested whether VLP immunization could induce protective immunity to HMPV by using a mouse model. C57BL/6 mice were injected twice intraperitoneally with VLPs alone or with adjuvant and subsequently challenged with HMPV. Mice were euthanized 5 days postinfection, and virus titers, levels of neutralizing antibodies, and numbers of CD3(+) T cells were quantified. Mice immunized with VLPs mounted an F-specific antibody response and generated CD8(+) T cells recognizing an F protein-derived epitope. VLP immunization induced a neutralizing-antibody response that was enhanced by the addition of either TiterMax Gold or α-galactosylceramide adjuvant, though adjuvant reduced cellular immune responses. Two doses of VLPs conferred complete protection from HMPV replication in the lungs of mice and were not associated with a Th2-skewed cytokine response. These results suggest that nonreplicating VLPs are a promising vaccine candidate for HMPV. IMPORTANCE Human metapneumovirus (HMPV) is a leading cause of acute respiratory infection in infants, children, and the elderly worldwide, yet no licensed vaccines exist. Live-attenuated vaccines present safety challenges, and protein subunit vaccines induce primarily antibody responses. Virus-like particles (VLPs) are an attractive alternative vaccine approach. We generated HMPV VLPs by expressing the viral matrix (M) and fusion (F) proteins in mammalian cells. We found that mice immunized with VLPs mounted an F-specific antibody response and generated CD8(+) T cells recognizing an F protein-derived epitope. VLP immunization induced a neutralizing-antibody response that was enhanced by the addition of either TiterMax Gold or α-galactosylceramide adjuvant. Two doses of VLPs conferred complete protection against HMPV replication in the lungs of mice and were not associated with a Th2-skewed cytokine response. These results suggest that nonreplicating VLPs are a promising vaccine candidate for HMPV.
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18
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Human metapneumovirus SH and G glycoproteins inhibit macropinocytosis-mediated entry into human dendritic cells and reduce CD4+ T cell activation. J Virol 2014; 88:6453-69. [PMID: 24672038 DOI: 10.1128/jvi.03261-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Human metapneumovirus (HMPV) is a major etiologic agent of respiratory disease worldwide. HMPV reinfections are common in healthy adults and children, suggesting that the protective immune response to HMPV is incomplete and short-lived. We used gene-deletion viruses to evaluate the role of the attachment G and small hydrophobic SH glycoproteins on virus uptake by primary human monocyte-derived dendritic cells (MDDC) in vitro and on subsequent MDDC maturation and activation of autologous T cells. HMPV with deletion of G and SH (ΔSHG) exhibited increased infectivity but had little effect on MDDC maturation. However, MDDC stimulated with ΔSHG induced increased proliferation of autologous Th1-polarized CD4(+) T cells. This effect was independent of virus replication. Increased T cell proliferation was strictly dependent on contact between virus-stimulated MDDC and CD4(+) T cells. Confocal microscopy revealed that deletion of SH and G was associated with an increased number of immunological synapses between memory CD4(+) T cells and virus-stimulated MDDC. Uptake of HMPV by MDDC was found to be primarily by macropinocytosis. Uptake of wild-type (WT) virus was reduced compared to that of ΔSHG, indicative of inhibition by the SH and G glycoproteins. In addition, DC-SIGN-mediated endocytosis provided a minor alternative pathway that depended on SH and/or G and thus operated only for WT. Altogether, our results show that SH and G glycoproteins reduce the ability of HMPV to be internalized by MDDC, resulting in a reduced ability of the HMPV-stimulated MDDC to activate CD4(+) T cells. This study describes a previously unknown mechanism of virus immune evasion. IMPORTANCE Human metapneumovirus (HMPV) is a major etiologic agent of respiratory disease worldwide. HMPV reinfections are common in healthy adults and children, suggesting that the protective immune response to HMPV is incomplete and short-lived. We found that HMPV attachment G and small hydrophobic SH glycoproteins reduce the ability of HMPV to be internalized by macropinocytosis into human dendritic cells (DC). This results in a reduced ability of the HMPV-stimulated DC to activate Th1-polarized CD4(+) T cells. These results contribute to a better understanding of the nature of incomplete protection against this important human respiratory virus, provide new information on the entry of HMPV into human cells, and describe a new mechanism of virus immune evasion.
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Mode of parainfluenza virus transmission determines the dynamics of primary infection and protection from reinfection. PLoS Pathog 2013; 9:e1003786. [PMID: 24278024 PMCID: PMC3836739 DOI: 10.1371/journal.ppat.1003786] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 10/08/2013] [Indexed: 11/19/2022] Open
Abstract
Little is known about how the mode of respiratory virus transmission determines the dynamics of primary infection and protection from reinfection. Using non-invasive imaging of murine parainfluenza virus 1 (Sendai virus) in living mice, we determined the frequency, timing, dynamics, and virulence of primary infection after contact and airborne transmission, as well as the tropism and magnitude of reinfection after subsequent challenge. Contact transmission of Sendai virus was 100% efficient, phenotypically uniform, initiated and grew to robust levels in the upper respiratory tract (URT), later spread to the lungs, grew to a lower level in the lungs than the URT, and protected from reinfection completely in the URT yet only partially in the lungs. Airborne transmission through 7.6-cm and 15.2-cm separations between donor and recipient mice was 86%-100% efficient. The dynamics of primary infection after airborne transmission varied between individual mice and included the following categories: (a) non-productive transmission, (b) tracheal dominant, (c) tracheal initiated yet respiratory disseminated, and (d) nasopharyngeal initiated yet respiratory disseminated. Any previous exposure to Sendai virus infection protected from mortality and severe morbidity after lethal challenge. Furthermore, a higher level of primary infection in a given respiratory tissue (nasopharynx, trachea, or lungs) was inversely correlated with the level of reinfection in that same tissue. Overall, the mode of transmission determined the dynamics and tropism of primary infection, which in turn governed the level of seroconversion and protection from reinfection. These data are the first description of the dynamics of respiratory virus infection and protection from reinfection throughout the respiratory tracts of living animals after airborne transmission. This work provides a basis for understanding parainfluenza virus transmission and protective immunity and for developing novel vaccines and non-pharmaceutical interventions.
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Céspedes PF, Gonzalez PA, Kalergis AM. Human metapneumovirus keeps dendritic cells from priming antigen-specific naive T cells. Immunology 2013; 139:366-76. [PMID: 23374037 DOI: 10.1111/imm.12083] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 12/30/2012] [Accepted: 01/28/2013] [Indexed: 12/22/2022] Open
Abstract
Human metapneumovirus (hMPV) is the second most common cause of acute lower respiratory tract infections in children, causing a significant public health burden worldwide. Given that hMPV can repeatedly infect the host without major antigenic changes, it has been suggested that hMPV may have evolved molecular mechanisms to impair host adaptive immunity and, more specifically, T-cell memory. Recent studies have shown that hMPV can interfere with superantigen-induced T-cell activation by infecting conventional dendritic cells (DCs). Here, we show that hMPV infects mouse DCs in a restricted manner and induces moderate maturation. Nonetheless, hMPV-infected DCs are rendered inefficient at activating naive antigen-specific CD4(+) T cells (OT-II), which not only display reduced proliferation, but also show a marked reduction in surface activation markers and interleukin-2 secretion. Decreased T-cell activation was not mediated by interference with DC-T-cell immunological synapse formation as recently described for the human respiratory syncytial virus (hRSV), but rather by soluble factors secreted by hMPV-infected DCs. These data suggest that although hMPV infection is restricted within DCs, it is sufficient to interfere with their capacity to activate naive T cells. Altogether, by interfering with DC function and productive priming of antigen-inexperienced T cells, hMPV could impair the generation of long-term immunity.
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Affiliation(s)
- Pablo F Céspedes
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Santiago, Chile
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Lévy C, Aerts L, Hamelin MÈ, Granier C, Szécsi J, Lavillette D, Boivin G, Cosset FL. Virus-like particle vaccine induces cross-protection against human metapneumovirus infections in mice. Vaccine 2013; 31:2778-85. [PMID: 23583815 DOI: 10.1016/j.vaccine.2013.03.051] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/17/2013] [Accepted: 03/28/2013] [Indexed: 11/28/2022]
Abstract
Human metapneumovirus (HMPV) is a paramyxovirus that causes acute respiratory-tract infections in children and adults worldwide. A safe and effective vaccine could decrease the burden of disease associated with this novel pathogen. We engineered HMPV viral-like particles (HMPV-VLPs) derived from retroviral core particles that mimic the properties of the viral surface of two HMPV viruses of either lineage A or B. These VLPs functionally display F and G HMPV surface glycoproteins. When injected in mice, HMPV-VLPs induce strong humoral immune response against both homologous and heterologous strains. Moreover, the induced neutralizing antibodies prevented mortality upon subsequent infection of the lungs with both homologous and heterologous viruses. Upon challenge, viral titers in the lungs of immunized animals were significantly reduced as compared to those of control animals. In conclusion, a HMPV-VLP vaccine that induces cross-protective immunity in mice is a promising approach to prevent HMPV infections.
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Affiliation(s)
- Camille Lévy
- CIRI, International Center for Infectiology Research, EVIR Team, Université de Lyon, Lyon, France
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22
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Abstract
The transmission of human metapneumovirus (hMPV) among family members is not well understood. We identified 15 families in which multiple members were diagnosed with hMPV infection by real-time PCR in 2008 and 2010. Index patients ranged in age from 2 years to 11 years (median 5 years), and all 15 index cases were children who attended primary school, kindergarten, or nursery school. Contact patients ranged in age from 2 months to 46 years (median 6 years). Excluding five adult cases, contact patients were significantly younger than index patients (P = 0·0389). Of the 12 contact children, seven (58%) were infants who were taken care of at home. The serial interval between the onset of symptoms in an index patient and the onset of symptoms in a contact patient was estimated to be 5 days. These results suggest that the control of school-based outbreaks is important for preventing hMPV infection in infants.
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