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Abstract
PURPOSE OF REVIEW Neuraminidase inhibitors (NAIs), including oseltamivir, zanamivir, and peramivir, is the main class of antiviral available for clinical use. As such, development of resistance toward these agents is of great clinical and public health concern. RECENT FINDINGS At present, NAI resistance remains uncommon among the circulating viruses (oseltamivir <3.5%, zanamivir <1%). Resistance risk is slightly higher in A(H1N1) than A(H3N2) and B viruses. Resistance may emerge during drug exposure, particularly among young children (<5 years), the immunocompromised, and individuals receiving prophylactic regimens. H275Y A(H1N1) variant, showing high-level oseltamivir resistance, is capable of causing outbreaks. R294K A(H7N9) variant shows reduced inhibition across NAIs. Multi-NAI resistance has been reported in the immunocompromised. SUMMARY These findings highlight the importance of continuous surveillance, and assessment of viral fitness and transmissibility of resistant virus strains. Detection can be challenging, especially in a mix of resistant and wild-type viruses. Recent advances in molecular techniques (e.g. targeted mutation PCR, iART, ddPCR, pyrosequencing, next-generation sequencing) have improved detection and our understanding of viral dynamics. Treatment options available for oseltamivir-resistant viruses are limited, and susceptibility testing of other NAIs may be required, but non-NAI antivirals (e.g. polymerase inhibitors) that are active against these resistant viruses are in late-stage clinical development.
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Zou X, Guo Q, Zhang W, Chen H, Bai W, Lu B, Zhang W, Fan Y, Liu C, Wang Y, Zhou F, Cao B. Dynamic Variation and Reversion in the Signature Amino Acids of H7N9 Virus During Human Infection. J Infect Dis 2019; 218:586-594. [PMID: 29688498 PMCID: PMC6047446 DOI: 10.1093/infdis/jiy217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/22/2018] [Indexed: 11/25/2022] Open
Abstract
Background Signature amino acids of H7N9 influenza A virus play critical roles in human adaption and pathogenesis, but their dynamic variation is unknown during disease development. Methods We sequentially collected respiratory samples from H7N9 patients at different timepoints and applied next-generation sequencing (NGS) to the whole genome of the H7N9 virus to investigate the variation at signature sites. Results A total of 11 patients were involved, from whom 29 samples were successfully sequenced, including samples from multiple timepoints in 9 patients. Neuraminidase (NA) R292K, basic polymerase 2 (PB2) E627K, and D701N were the 3 most dynamic mutations. The oseltamivir resistance-related NA R292K mutation was present in 9 samples from 5 patients, including 1 sample obtained before antiviral therapy. In all patients with the NA 292K mutation, the oseltamivir-sensitive 292R genotype persisted and was not eliminated by antiviral treatment. The PB2 E627K substitution was present in 18 samples from 8 patients, among which 12 samples demonstrated a mixture of E/K and the 627K frequency exhibited dynamic variation. Dual D701N and E627K mutations emerged but failed to achieve predominance in any of the samples. Conclusions Signature amino acids in PB2 and NA demonstrated high polymorphism and dynamic variation within individual patients during H7N9 virus infection.
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Affiliation(s)
- Xiaohui Zou
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Qiang Guo
- Department of Respiratory, Emergency and Critical Care Medicine, First Affiliated Hospital of Soochow University, Jiangsu
| | - Wei Zhang
- First Affiliated Hospital of Nanchang University, Jiangxi, People's Republic of China
| | - Hui Chen
- Department of Respiratory, Emergency and Critical Care Medicine, First Affiliated Hospital of Soochow University, Jiangsu
| | - Wei Bai
- First Affiliated Hospital of Nanchang University, Jiangxi, People's Republic of China
| | - Binghuai Lu
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Wang Zhang
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Yanyan Fan
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Chao Liu
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Yeming Wang
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Fei Zhou
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
| | - Bin Cao
- Department of Pulmonary and Critical Care Medicine, Laboratory of Clinical Microbiology and Infectious Diseases, Center for Respiratory Diseases, China-Japan Friendship Hospital, National Clinical Research Centre for Respiratory Disease, Beijing
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Abstract
Infectious disease represent the most significant threat to human health. Significant geologic cataclysmic events have caused the extinction of countless species, but these “Wrath of God” events predate the emergence of Homo sapiens. Pandemic infections have accompanied the rise of human civilization frequently re-occurring leaving a lasting imprint on human history punctuated by profound loss of life. Emerging infections become endemic and are here to stay marking their presence with an annual death toll. Each decade brings a new onslaught of emerging infectious agents. We are surprised again and again but are never prepared. The long-term consequences often remain unrecognized and are always inconvenient including cancer, cardiovascular disease and immune associated diseases that threaten our health. Reliance on clusters of clinical symptoms in the face of diverse and non-descriptive viral infection symptoms is a foolhardy form of crisis management. Viral success is based on rapid replication resulting in large numbers. Single-stranded RNA viruses with their high replication error rate represent a paradigm for resilience.
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Rapid and simple detection of Tamiflu-resistant influenza virus: Development of oseltamivir derivative-based lateral flow biosensor for point-of-care (POC) diagnostics. Sci Rep 2018; 8:12999. [PMID: 30158601 PMCID: PMC6115449 DOI: 10.1038/s41598-018-31311-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/16/2018] [Indexed: 01/16/2023] Open
Abstract
We have developed a novel oseltamivir derivative (oseltamivir hexylthiol; OHT) that exhibits a higher binding affinity for Tamiflu-resistant virus (Tamiflu resistance) than for the wild-type virus (Tamiflu-susceptible virus; WT) as an antibody. First, OHT-modified gold nanoparticles (OHT-GNPs) are used in a simple colorimetric assay as nanoprobes for the Tamiflu-resistant virus. In the presence of Tamiflu-resistant virus, they show a colorimetric change from deep red to purple because of the OHT-GNP aggregation driven by strong interactions between OHT and neuraminidase (NA) on the surface of the Tamiflu-resistance. Moreover, the color gradually turns purple as the concentration of the Tamiflu-resistant virus increases, allowing the determination of the presence of the virus with the naked eye. Furthermore, an OHT-based lateral flow assay (LFA) has been developed as a rapid and easy detection device for Tamiflu resistance. It shows detection specificity for various virus concentrations of Tamiflu-resistant virus even for the mixture of WT and Tamiflu-resistant viruses, where the limit of detection (LOD) is 5 × 102 ~ 103 PFU per test (=1 × 104 PFU/mL). It has been confirmed that this platform can provide accurate information on whether a virus exhibits Tamiflu resistance, thus supporting the selection of appropriate treatments using point-of-care (POC) diagnostics.
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Yang Y, Li S, Wong G, Ma S, Xu Z, Zhao X, Li H, Xu W, Zheng H, Lin J, Zhao Q, Liu W, Liu Y, Gao GF, Bi Y. Development of a quadruple qRT-PCR assay for simultaneous identification of highly and low pathogenic H7N9 avian influenza viruses and characterization against oseltamivir resistance. BMC Infect Dis 2018; 18:406. [PMID: 30111290 PMCID: PMC6094886 DOI: 10.1186/s12879-018-3302-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/01/2018] [Indexed: 11/22/2022] Open
Abstract
Background During the fifth wave of human H7N9 infections, a novel highly pathogenic (HP) H7N9 variant emerged with an insertion of multiple basic amino acids in the HA cleavage site. Moreover, a neuraminidase inhibitor (NAI) resistance (R292K in NA) mutation was found in H7N9 isolates from humans, poultry and the environment. In this study, we set out to develop and validate a multiplex quantitative reverse transcript polymerase chain reaction (qRT-PCR) to simultaneously detect the presence of H7N9 and further identify the HP and NAI-resistance mutations. Methods A quadruple qRT-PCR to simultaneously detect the presence of H7N9 and further identify the HP and NAI-resistance mutations was designed based on the analyses of the HA and NA genes of H7N9. This assay was further tested for specificity and sensitivity, and validated using clinical samples. Results The assay was highly specific and able to detect low pathogenic (LP)- or HP-H7N9 with/without the NAI-resistance mutation. The detection limit of the assay was determined to be 50 genome-equivalent copies and 2.8 × 10− 3 50% tissue culture infectious doses (TCID50) of live H7N9 per reaction. Clinical validation was confirmed by commercial kits and Sanger sequencing with ten clinical samples. Conclusions We developed and validated a rapid, single-reaction, one-step, quadruple real-time qRT-PCR to simultaneously detect the presence of H7N9 and further identify the HP- and NAI-resistance strains with excellent performance in specificity and sensitivity. This assay could be used to monitor the evolution of H7N9 viruses in the laboratory, field and the clinic for early-warning and the prevention of H7N9 infections.
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Affiliation(s)
- Yang Yang
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China.,CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China
| | - Shanqin Li
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China.,CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China
| | - Gary Wong
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China.,CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China
| | - Sufang Ma
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhixiang Xu
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China
| | - Xiaonan Zhao
- Yunnan Center for Disease Control and Prevention, Kunming, 650022, China
| | - Hong Li
- Yunnan Center for Disease Control and Prevention, Kunming, 650022, China
| | - Wen Xu
- Yunnan Center for Disease Control and Prevention, Kunming, 650022, China
| | - Haixia Zheng
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China
| | - Jingyan Lin
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China
| | - Qi Zhao
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China
| | - Wenjun Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China
| | - Yingxia Liu
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China.,University of Chinese Academy of Sciences Medical School, Chinese Academy of Sciences, Beijing, 101408, China
| | - George F Gao
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China.,CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China.,National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (China CDC), Beijing, 102206, China.,University of Chinese Academy of Sciences Medical School, Chinese Academy of Sciences, Beijing, 101408, China
| | - Yuhai Bi
- Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen Third People's Hospital, Shenzhen, 518112, China. .,CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing, 100101, China.
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McKimm-Breschkin JL, Jiang S, Hui DS, Beigel JH, Govorkova EA, Lee N. Prevention and treatment of respiratory viral infections: Presentations on antivirals, traditional therapies and host-directed interventions at the 5th ISIRV Antiviral Group conference. Antiviral Res 2018; 149:118-142. [PMID: 29162476 PMCID: PMC7133686 DOI: 10.1016/j.antiviral.2017.11.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
The International Society for Influenza and other Respiratory Virus Diseases held its 5th Antiviral Group (isirv-AVG) Conference in Shanghai, China, in conjunction with the Shanghai Public Health Center and Fudan University from 14-16 June 2017. The three-day programme encompassed presentations on some of the clinical features, management, immune responses and virology of respiratory infections, including influenza A(H1N1)pdm09 and A(H7N9) viruses, MERS-CoV, SARS-CoV, adenovirus Type 80, enterovirus D68, metapneumovirus and respiratory syncytial virus (RSV). Updates were presented on several therapeutics currently in clinical trials, including influenza polymerase inhibitors pimodivir/JNJ6362387, S033188, favipiravir, monoclonal antibodies MHAA45449A and VIS410, and host directed strategies for influenza including nitazoxanide, and polymerase ALS-008112 and fusion inhibitors AK0529, GS-5806 for RSV. Updates were also given on the use of the currently licensed neuraminidase inhibitors. Given the location in China, there were also presentations on the use of Traditional Chinese Medicines. Following on from the previous conference, there were ongoing discussions on appropriate endpoints for severe influenza in clinical trials from regulators and clinicians, an issue which remains unresolved. The aim of this conference summary is to provide information for not only conference participants, but a detailed referenced review of the current status of clinical trials, and pre-clinical development of therapeutics and vaccines for influenza and other respiratory diseases for a broader audience.
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Affiliation(s)
| | - Shibo Jiang
- College of Basic Medical Sciences, Fudan University, Shanghai, China; Lindsley F. Kimball Research Institute, New York Blood Center, NY, USA
| | - David S Hui
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong Special Administrative Region
| | - John H Beigel
- Leidos Biomedical Research, Inc., Support to National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Elena A Govorkova
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, USA
| | - Nelson Lee
- Faculty of Medicine and Dentistry, University of Alberta, Canada
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Shaffer SM, Joshi RP, Chambers BS, Sterken D, Biaesch AG, Gabrieli DJ, Li Y, Feemster KA, Hensley SE, Issadore D, Raj A. Multiplexed detection of viral infections using rapid in situ RNA analysis on a chip. LAB ON A CHIP 2015; 15:3170-82. [PMID: 26113495 PMCID: PMC4670042 DOI: 10.1039/c5lc00459d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Viral infections are a major cause of human disease, but many require molecular assays for conclusive diagnosis. Current assays typically rely on RT-PCR or ELISA; however, these tests often have limited speed, sensitivity or specificity. Here, we demonstrate that rapid RNA FISH is a viable alternative method that could improve upon these limitations. We describe a platform beginning with software to generate RNA FISH probes both for distinguishing related strains of virus (even those different by a single base) and for capturing large numbers of strains simultaneously. Next, we present a simple fluidic device for reliably performing RNA FISH assays in an automated fashion. Finally, we describe an automated image processing pipeline to robustly identify uninfected and infected samples. Together, our results establish RNA FISH as a methodology with potential for viral point-of-care diagnostics.
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Affiliation(s)
- Sydney M Shaffer
- Department of Bioengineering, University of Pennsylvania, Philadelphia, USA.
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Abstract
BACKGROUND The clinical features of avian-origin influenza virus A (H7N9) virus infection have been extensively characterized, but viral RNA detection in extra-pulmonary samples has seldom been studied. OBJECTIVES To study shedding of viral RNA in extra pulmonary samples in patients with avian influenza H7N9 infections. STUDY DESIGN A retrospective study of throat swabs, urine, fecal samples and sera collected sequentially from 18 hospitalized patients with H7N9 infections in Shanghai, China, between April and July in 2013 was conducted. RESULTS Viral RNA could be detected in urine samples from 17 patients, in fecal samples from 15 and in sera from 14 with a real-time reverse transcription polymerase chain reaction. The median duration of shedding of viral RNA was 19.7 days in throat swabs, 22 days in feces, 21.1 days in urines and 16.2 days in sera, indicating prolonged shedding of viral RNA in feces and urine compared with that in throat swabs. Prolonged duration of viral RNA detection in throat swabs and urine samples was observed in more severe patients. Moreover, in previously reported oseltamivir resistant patients, the NA gene with a 292K mutation could also be detected in their extra-pulmonary as well as in their respiratory samples. CONCLUSION Our data indicated a high frequency of viral RNA detection in feces, urine and sera in H7N9-infected patients and pointed out the potential risk of transmission.
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Drug susceptibility profile and pathogenicity of H7N9 influenza virus (Anhui1 lineage) with R292K substitution. Emerg Microbes Infect 2014; 3:e78. [PMID: 26038501 PMCID: PMC4274890 DOI: 10.1038/emi.2014.80] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 09/21/2014] [Accepted: 09/22/2014] [Indexed: 01/19/2023]
Abstract
Neuraminidase inhibitors (NAIs) are the only available licensed therapeutics against human H7N9 influenza virus infections. The emergence of NAI-resistant variants of H7N9viruses with an NA R292K mutation poses a therapeutic challenge. A comprehensive understanding of the susceptibility of these viruses to clinically available NAIs, non-NAIs and their combinations is crucial for effective treatment. In this study, by using limited serial passage and plaque purification, an R292K variant of the Anhui1 lineage was isolated from a patient with clinical evidence of resistance to oseltamivir. In vitro and cell-based assays confirmed a high level of resistance conferred by the R292K mutation to oseltamivir carboxylate and a moderate level of resistance to zanamivir and peramivir. Non-NAI antivirals, such as T-705, ribavirin and NT-300, efficiently inhibited both the variant and the wild-type in cell-based assays. A combination of NAIs and non-NAIs did not exhibit a marked synergistic effect against the R292K variant. However, the combination of two non-NAIs (T-705 and ribavirin) exhibited significant synergism against the mutant virus. In experimentally infected mice, the variant showed delayed onset of symptoms, a reduced viral load and attenuated lethality compared with the wild-type. Our study suggested non-NAIs should be tested clinically for H7N9 patients with a sustained high viral load. Possible drug combination regimens, such as T-705 plus ribavirin, should be further tested in animal models. The pathogenicity and transmissibility of the R292K H7N9 variant should be further assessed with genetically well-characterized pairs of viruses and, most-desirably, with competitive fitness experiments.
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Yen HL, Zhou J, Choy KT, Sia SF, Teng O, Ng IH, Fang VJ, Hu Y, Wang W, Cowling BJ, Nicholls JM, Guan Y, Peiris JSM. The R292K mutation that confers resistance to neuraminidase inhibitors leads to competitive fitness loss of A/Shanghai/1/2013 (H7N9) influenza virus in ferrets. J Infect Dis 2014; 210:1900-8. [PMID: 24951824 DOI: 10.1093/infdis/jiu353] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Neuraminidase (NA) inhibitors are the only licensed therapeutic option for human zoonotic H7N9 infections. An NA-R292K mutation that confers broad-spectrum resistance to NA inhibitors has been documented in H7N9 patients after treatment. METHODS We evaluated the transmission potential of a human influenza A H7N9 isolate with a NA-R292K mutation in the ferret model followed by genotyping assay to monitor its competitive fitness in vivo. RESULTS Plaque-purified A/Shanghai/1/2013 wild-type and NA-R292K viruses transmitted at comparable efficiency to direct or respiratory droplet contact ferrets. In ferrets inoculated with the plaque-purified A/Shanghai/1/2013 NA-R292K virus with dominant K292 (94%), the resistant K292 genotype was outgrown by the wild-type R292 genotype during the course of infection. Transmission of the resistant K292 genotype was detected in 3/4 direct contact and 3/4 respiratory droplet contact ferrets at early time points but was gradually replaced by the wild-type genotype. In the respiratory tissues of inoculated or infected ferrets, the wild-type R292 genotype dominated in the nasal turbinate, whereas the resistant K292 genotype was more frequently detected in the lungs. CONCLUSIONS The NA inhibitor-resistant H7N9 virus with the NA-R292K mutation may transmit among ferrets but showed compromised fitness in vivo while in competition with the wild-type virus.
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Affiliation(s)
| | | | | | | | | | | | | | - Yunwen Hu
- Shanghai Public Health Clinical Center, China
| | - Wei Wang
- Shanghai Public Health Clinical Center, China
| | | | - John M Nicholls
- Department of Pathology, LKS Faculty of Medicine, University of Hong Kong, Hong Kong SAR
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