1
|
Hooi YT, Balasubramaniam VRMT. In vitro and in vivo models for the study of EV-D68 infection. Pathology 2023; 55:907-916. [PMID: 37852802 DOI: 10.1016/j.pathol.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/03/2023] [Accepted: 08/14/2023] [Indexed: 10/20/2023]
Abstract
Enterovirus D68 (EV-D68) is one of hundreds of non-polio enteroviruses that typically cause cold-like respiratory illness. The first EV-D68 outbreak in the United States in 2014 aroused widespread concern among the public and health authorities. The infection was found to be associated with increased surveillance of acute flaccid myelitis, a neurological condition that causes limb paralysis in conjunction with spinal cord inflammation. In vitro studies utilising two-dimensional (2D) and three-dimensional (3D) culture systems have been employed to elucidate the pathogenic mechanism of EV-D68. Various animal models have also been developed to investigate viral tropism and distribution, pathogenesis, and immune responses during EV-D68 infection. EV-D68 infections have primarily been investigated in respiratory, intestinal and neural cell lines/tissues, as well as in small-size immunocompetent rodent models that were limited to a young age. Some studies have implemented strategies to overcome the barriers by using immunodeficient mice or virus adaptation. Although the existing models may not fully recapitulate both respiratory and neurological disease observed in human EV-D68 infection, they have been valuable for studying pathogenesis and evaluating potential vaccine or therapeutic candidates. In this review, we summarise the methodologies and findings from each experimental model and discuss their applications and limitations.
Collapse
Affiliation(s)
- Yuan Teng Hooi
- Infection and Immunity Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia.
| | - Vinod R M T Balasubramaniam
- Infection and Immunity Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia.
| |
Collapse
|
2
|
Masmoudi F, Santos-Ferreira N, Pajkrt D, Wolthers KC, DeGroot J, Vlaming MLH, Rocha-Pereira J, Buti L. Evaluation of 3D Human Intestinal Organoids as a Platform for EV-A71 Antiviral Drug Discovery. Cells 2023; 12:cells12081138. [PMID: 37190047 DOI: 10.3390/cells12081138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/24/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023] Open
Abstract
Enteroviruses are a leading cause of upper respiratory tract, gastrointestinal, and neurological infections. Management of enterovirus-related diseases has been hindered by the lack of specific antiviral treatment. The pre-clinical and clinical development of such antivirals has been challenging, calling for novel model systems and strategies to identify suitable pre-clinical candidates. Organoids represent a new and outstanding opportunity to test antiviral agents in a more physiologically relevant system. However, dedicated studies addressing the validation and direct comparison of organoids versus commonly used cell lines are lacking. Here, we described the use of human small intestinal organoids (HIOs) as a model to study antiviral treatment against human enterovirus 71 (EV-A71) infection and compared this model to EV-A71-infected RD cells. We used reference antiviral compounds such as enviroxime, rupintrivir, and 2'-C-methylcytidine (2'CMC) to assess their effects on cell viability, virus-induced cytopathic effect, and viral RNA yield in EV-A71-infected HIOs and cell line. The results indicated a difference in the activity of the tested compounds between the two models, with HIOs being more sensitive to infection and drug treatment. In conclusion, the outcome reveals the value added by using the organoid model in virus and antiviral studies.
Collapse
Affiliation(s)
- Fatma Masmoudi
- Charles River Laboratories, 2333 CR Leiden, The Netherlands
- OrganoVIR Labs, Department of Medical Microbiology, Amsterdam UMC Location Academic Medical Center, Amsterdam Institute for Infection and Immunity, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Nanci Santos-Ferreira
- Laboratory of Virology and Chemotherapy, KU Leuven-Department of Microbiology, Immunology and Transplantation, Rega Institute, 3000 Leuven, Belgium
| | - Dasja Pajkrt
- OrganoVIR Labs, Pediatric Infectious Diseases, Emma Children's Hospital, Amsterdam UMC Location University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Katja C Wolthers
- OrganoVIR Labs, Department of Medical Microbiology, Amsterdam UMC Location Academic Medical Center, Amsterdam Institute for Infection and Immunity, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Jeroen DeGroot
- Charles River Laboratories, 2333 CR Leiden, The Netherlands
| | | | - Joana Rocha-Pereira
- Laboratory of Virology and Chemotherapy, KU Leuven-Department of Microbiology, Immunology and Transplantation, Rega Institute, 3000 Leuven, Belgium
| | - Ludovico Buti
- Charles River Laboratories, 2333 CR Leiden, The Netherlands
| |
Collapse
|
3
|
Guo Y, Wang B, Gao H, He C, Hua R, Gao L, Du Y, Xu J. Insight into the Role of Psychological Factors in Oral Mucosa Diseases. Int J Mol Sci 2022; 23:ijms23094760. [PMID: 35563151 PMCID: PMC9099906 DOI: 10.3390/ijms23094760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 02/04/2023] Open
Abstract
With the development of psychology and medicine, more and more diseases have found their psychological origins and associations, especially ulceration and other mucosal injuries, within the digestive system. However, the association of psychological factors with lesions of the oral mucosa, including oral squamous cell carcinoma (OSCC), burning mouth syndrome (BMS), and recurrent aphthous stomatitis (RAS), have not been fully characterized. In this review, after introducing the association between psychological and nervous factors and diseases, we provide detailed descriptions of the psychology and nerve fibers involved in the pathology of OSCC, BMS, and RAS, pointing out the underlying mechanisms and suggesting the clinical indications.
Collapse
Affiliation(s)
- Yuexin Guo
- Department of Oral Medicine, Basic Medical College, Capital Medical University, Beijing 100069, China; (Y.G.); (Y.D.)
| | - Boya Wang
- Department of Clinical Medicine, Peking University Health Science Center, Beijing 100081, China;
| | - Han Gao
- Department of Physiology and Pathophysiology, Basic Medical College, Capital Medical University, Beijing 100069, China; (H.G.); (C.H.)
| | - Chengwei He
- Department of Physiology and Pathophysiology, Basic Medical College, Capital Medical University, Beijing 100069, China; (H.G.); (C.H.)
| | - Rongxuan Hua
- Department of Clinical Medicine, Basic Medical College, Capital Medical University, Beijing 100069, China;
| | - Lei Gao
- Department of Bioinformatics, College of Bioengineering, Capital Medical University, Beijing 100069, China;
| | - Yixuan Du
- Department of Oral Medicine, Basic Medical College, Capital Medical University, Beijing 100069, China; (Y.G.); (Y.D.)
| | - Jingdong Xu
- Department of Physiology and Pathophysiology, Basic Medical College, Capital Medical University, Beijing 100069, China; (H.G.); (C.H.)
- Correspondence: ; Tel./Fax: +86-10-8391-1469
| |
Collapse
|
4
|
Wang J, Hu Y, Zheng M. Enterovirus A71 antivirals: Past, present, and future. Acta Pharm Sin B 2022; 12:1542-1566. [PMID: 35847514 PMCID: PMC9279511 DOI: 10.1016/j.apsb.2021.08.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/28/2021] [Accepted: 08/12/2021] [Indexed: 02/07/2023] Open
Abstract
Enterovirus A71 (EV-A71) is a significant human pathogen, especially in children. EV-A71 infection is one of the leading causes of hand, foot, and mouth diseases (HFMD), and can lead to neurological complications such as acute flaccid myelitis (AFM) in severe cases. Although three EV-A71 vaccines are available in China, they are not broadly protective and have reduced efficacy against emerging strains. There is currently no approved antiviral for EV-A71. Significant progress has been made in developing antivirals against EV-A71 by targeting both viral proteins and host factors. However, viral capsid inhibitors and protease inhibitors failed in clinical trials of human rhinovirus infection due to limited efficacy or side effects. This review discusses major discoveries in EV-A71 antiviral development, analyzes the advantages and limitations of each drug target, and highlights the knowledge gaps that need to be addressed to advance the field forward.
Collapse
Affiliation(s)
- Jun Wang
- Department of Pharmacology and Toxicology, College of Pharmacy, the University of Arizona, Tucson, AZ 85721, USA
| | - Yanmei Hu
- Department of Pharmacology and Toxicology, College of Pharmacy, the University of Arizona, Tucson, AZ 85721, USA
| | - Madeleine Zheng
- Department of Pharmacology and Toxicology, College of Pharmacy, the University of Arizona, Tucson, AZ 85721, USA
| |
Collapse
|
5
|
Dai K, Tan JK, Qian W, Lee RCH, Hann Chu JJ, Zhou GC. Discovery of 14S-(2'-chloro-4'-nitrophenoxy)-8R/S,17-epoxy andrographolide as EV-A71 infection inhibitor. Biochem Pharmacol 2021; 194:114820. [PMID: 34748818 DOI: 10.1016/j.bcp.2021.114820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/18/2021] [Accepted: 11/02/2021] [Indexed: 01/23/2023]
Abstract
Human enterovirus A71 (EV-A71) is a major etiological agent of hand-foot-and-mouth disease (HFMD) and there is presently no internationally approved antiviral against EV-A71. In this study, it is disclosed that 14S-(2'-chloro-4'-nitrophenoxy)-8R/S,17-epoxy andrographolide (2) was discovered to be an effective inhibitor against EV-A71 infection showing significant reduction of viral titre. In addition to EV-A71, compound 2 exerts broad-spectrum antiviral effects against other enteroviruses. It is revealed that compound 2 inhibits the post-entry stages of EV-A71 viral replication cycle and significantly reduces viral protein expression of structural proteins such as VP0 and VP2 via inhibiting EV-A71 RNA replication. Moreover, the inhibitory property of compound 2 is specific to viral RNA replication. Furthermore, compound 2 is more likely to target a host factor in EV-A71 RNA replication. As a result, introduction of epoxide at positions 8 and 17 of andrographolide is effective for anti-EV-A71 infection and is a potential anti-EV-A71 strategy. Further work to discover more potent andrographolide derivatives and elucidate comprehensive SAR is under way.
Collapse
Affiliation(s)
- Kun Dai
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Jie Kai Tan
- Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545 Singapore, Singapore
| | - Weiyi Qian
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China
| | - Regina Ching Hua Lee
- Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545 Singapore, Singapore
| | - Justin Jang Hann Chu
- Laboratory of Molecular RNA Virology and Antiviral Strategies, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 117545 Singapore, Singapore; Infectious Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, 117597 Singapore, Singapore; Collaborative and Translation Unit for HFMD, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 138673 Singapore, Singapore.
| | - Guo-Chun Zhou
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu, China.
| |
Collapse
|
6
|
A hSCARB2-transgenic mouse model for Coxsackievirus A16 pathogenesis. Virol J 2021; 18:84. [PMID: 33882964 PMCID: PMC8061046 DOI: 10.1186/s12985-021-01557-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 04/14/2021] [Indexed: 11/11/2022] Open
Abstract
Background Coxsackievirus A16 (CA16) is one of the neurotropic pathogen that has been associated with severe neurological forms of hand, foot, and mouth disease (HFMD), but its pathogenesis is not yet clear. The limited host range of CA16 make the establishment of a suitable animal model that can recapitulate the neurological pathology observed in human HFMD more difficult. Because the human scavenger receptor class B, member 2 (hSCARB2) is a cellular receptor for CA16, we used transgenic mice bearing human SCARB2 and nasally infected them with CA16 to study the pathogenicity of the virus. Methods Coxsackievirus A16 was administered by intranasal instillation to groups of hSCARB2 transgenic mice and clinical signs were observed. Sampled at different time-points to document and characterize the mode of viral dissemination, pathological change and immune response of CA16 infection. Results Weight loss and virus replication in lung and brain were observed in hSCARB2 mice infected with CA16, indicating that these animals could model the neural infection process. Viral antigens were observed in the alveolar epithelia and brainstem cells. The typical histopathology was interstitial pneumonia with infiltration of significant lymphocytes into the alveolar interstitial in lung and diffuse punctate hemorrhages in the capillaries of the brainstem. In addition, we detected the expression levels of inflammatory cytokines and detected high levels of interleukin IL-1β, IL-6, IL-18, and IFN-γ in nasal mucosa, lungs and brain tissues. Conclusions The hSCARB2-transgenic mice can be productively infected with CA16 via respiratory route and exhibited a clear tropism to lung and brain tissues, which can serve as a model to investigate the pathogenesis of CA16 associated respiratory and neurological disease.
Collapse
|
7
|
Wang Y, Zhao H, Ou R, Zhu H, Gan L, Zeng Z, Yuan R, Yu H, Ye M. Epidemiological and clinical characteristics of severe hand-foot-and-mouth disease (HFMD) among children: a 6-year population-based study. BMC Public Health 2020; 20:801. [PMID: 32460823 PMCID: PMC7254654 DOI: 10.1186/s12889-020-08961-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/19/2020] [Indexed: 11/22/2022] Open
Abstract
Background Hand-foot-and-mouth disease (HFMD) is considered to be self-limited, however, severe HFMD is a deadly threat for children worldwide, therefore, it is essential to define the clinical and epidemiologic characteristics of children with severe HFMD and identify the risk factors of death. Methods Between 2013 and 2018, children who diagnosed with severe HFMD from Chongqing, China were enrolled in this population-based study. A total of 459 severe HFMD children cases were identified during the study period, including 415 survivors and 44 fatal cases. Demographic, geographical, epidemiological and clinical data of the cases were acquired and analyzed. Results Risk factors of the death because of severe HFMD children included female, aged 1 ~ 3 years, enterovirus 71 infection, falling ill in winter, more than one children in home, being taken care of by grandparents, the caregivers’ education not more than 9 years, having fever more than 3 days, consciousness disorders, general weakness, vomiting, general weakness, abnormal pupillary light reflex, repeated cough, tachypnea, moist rales, white frothy sputum, pink frothy sputum, and cyanosis on lips or the whole body, tachycardia, arrhythmia, cold limbs, pale complexion, weakened pulse. (all p < 0.05). Spatial-temporal analysis detected high-value clusters, the most likely cluster located at rural countries in the northern parts of Chongqing, from January, 2015 to July, 2017. (p < 0.01). Besides, some urban districts were also found high incidence of severe HFMD cases according to the incidence maps. Conclusions The detection of clinical risk factors and the temporal, spatial and socio-demographic distribution epidemiological characteristics of severe HFMD contribute to the timely diagnosis and intervention, the results of this study can be the reference of further clinical and public health practice.
Collapse
Affiliation(s)
- Yanhao Wang
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Chongqing Medical University, Chongqing, 400016, China.,College of Stomatology, Chongqing Medical University, Chongqing, 401147, China
| | - Han Zhao
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, No. 8, Changjiang 2nd Road, Chongqing, 400042, Yuzhong District, China
| | - Rong Ou
- Library, Chongqing Medical University, Chongqing, 400016, China
| | - Hua Zhu
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Chongqing Medical University, Chongqing, 400016, China
| | - Lidan Gan
- Pediatric College, Chongqing Medical University, Chongqing, 400014, China
| | - Zihuan Zeng
- College of Nursing, Chongqing Medical University, Chongqing, 400016, China
| | - Ruizhu Yuan
- College of Nursing, Chongqing Medical University, Chongqing, 400016, China
| | - Huan Yu
- College of Nursing, Chongqing Medical University, Chongqing, 400016, China
| | - Mengliang Ye
- Department of Epidemiology and Health Statistics, School of Public Health and Management, Chongqing Medical University, Chongqing, 400016, China.
| |
Collapse
|
8
|
Viral engagement with host receptors blocked by a novel class of tryptophan dendrimers that targets the 5-fold-axis of the enterovirus-A71 capsid. PLoS Pathog 2019; 15:e1007760. [PMID: 31071193 PMCID: PMC6590834 DOI: 10.1371/journal.ppat.1007760] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 06/24/2019] [Accepted: 04/12/2019] [Indexed: 12/31/2022] Open
Abstract
Enterovirus A71 (EV-A71) is a non-polio neurotropic enterovirus with pandemic potential. There are no antiviral agents approved to prevent or treat EV-A71 infections. We here report on the molecular mechanism by which a novel class of tryptophan dendrimers inhibits (at low nanomolar to high picomolar concentration) EV-A71 replication in vitro. A lead compound in the series (MADAL385) prevents binding and internalization of the virus but does not, unlike classical capsid binders, stabilize the particle. By means of resistance selection, reverse genetics and cryo-EM, we map the binding region of MADAL385 to the 5-fold vertex of the viral capsid and demonstrate that a single molecule binds to each vertex. By interacting with this region, MADAL385 prevents the interaction of the virus with its cellular receptors PSGL1 and heparan sulfate, thereby blocking the attachment of EV-A71 to the host cells. Enterovirus A71 (EV-A71) is the virus responsible for most of the severe forms of hand, foot and mouth disease (HFMD) associated with neurological involvement and mortality in young children under the age of 5. Seasonal outbreaks of HFMD -with a 2–3 years epidemic cycle- are recurring around the world, especially in the Asia-Pacific region. To date, no antiviral agent has been approved for the treatment of EV-A71 infections. Here, we report on a recently uncovered class of tryptophan dendrimers with an extraordinary antiviral activity in vitro against circulating EV-A71 clinical isolates. Mode of action studies revealed that this class of compounds targets the 5-fold vertex of EV-A71, in turn blocking receptor binding. Our finding may open an entirely novel line of research and largely aid in anti-enterovirus drug development.
Collapse
|
9
|
Madakshira MG, Bhardwaj S, Gupta K, Chander Y, Bhalla A. A fatal case of enterovirus infection with secondary hemophagocytosis-case report with review of literature. APMIS 2018; 126:877-882. [PMID: 30357959 DOI: 10.1111/apm.12892] [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: 08/01/2018] [Accepted: 09/25/2018] [Indexed: 11/28/2022]
Abstract
Enterovirus is a common viral infection, which can affect multiple organ systems with an array of clinical presentation such as meningitis, encephalitis, myocarditis, and disseminated infections. The illness is usually asymptomatic and self-limited but few cases can be severe and life-threatening especially when associated with hemophagocytosis. We discuss a fatal case of disseminated enterovirus infection and the histomorphological features of the infection.
Collapse
Affiliation(s)
- Manoj Gopal Madakshira
- Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sunny Bhardwaj
- Department of Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Kirti Gupta
- Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Yogesh Chander
- Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Ashish Bhalla
- Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| |
Collapse
|
10
|
Regional, age and respiratory-secretion-specific prevalence of respiratory viruses associated with asthma exacerbation: a literature review. Arch Virol 2018; 163:845-853. [PMID: 29327237 PMCID: PMC7087223 DOI: 10.1007/s00705-017-3700-y] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 12/18/2017] [Indexed: 12/11/2022]
Abstract
Despite increased understanding of how viral infection is involved in asthma exacerbations, it is less clear which viruses are involved and to what extent they contribute to asthma exacerbations. Here, we sought to determine the prevalence of different respiratory viruses during asthma exacerbations. Systematic computerized searches of the literature up to June 2017 without language limitation were performed. The primary focus was on the prevalence of respiratory viruses, including AdV (adenovirus), BoV (bocavirus), CoV (coronavirus), CMV (cytomegalovirus), EnV (enterovirus), HSV (herpes simplex virus), IfV (influenza virus), MpV (metapneumovirus), PiV (parainfluenzavirus), RV (rhinovirus) and RSV (respiratory syncytial virus) during asthma exacerbations. We also examined the prevalence of viral infection stratified by age, geographic region, type of respiratory secretion, and detection method. Sixty articles were included in the final analysis. During asthma exacerbations, the mean prevalence of AdV, BoV, CoV, CMV, EnV, HSV, IfV, MpV, PiV, RV and RSV was 3.8%, 6.9%, 8.4%, 7.2%, 10.1%, 12.3%, 10.0%, 5.3%, 5.6%, 42.1% and 13.6%, respectively. EnV, MPV, RV and RSV were more prevalent in children, whereas AdV, BoV, CoV, IfV and PiV were more frequently present in adults. RV was the major virus detected globally, except in Africa. RV could be detected in both the upper and lower airway. Polymerase chain reaction was the most sensitive method for detecting viral infection. Our findings indicate the need to develop prophylactic polyvalent or polyvirus (including RV, EnV, IfV and RSV) vaccines that produce herd immunity and reduce the healthcare burden associated with virus-induced asthma exacerbations.
Collapse
|