DOCSLIB.ORG

Investigations Into the Novel Proteins of Influenza B

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Investigations Into the Novel Proteins of Influenza B Imperial College London Investigations into the novel proteins of influenza B Ruth Alice Elderfield Supervisor: Professor Wendy Barclay Department of Infectious Diseases Doctor of Philosophy 2010 Declaration I confirm that this is my own work, the use of all materials from other sources has been properly acknowledged and that this work has not previously been submitted for a degree at Imperial College London or any other institution Ruth Elderfield 2 Acknowledgements I owe thanks to: A series of amazing ladies helped me get this far: Sarah Howell, Judith Taylor, Jane Reed, Crystal Baker, Maxine Allen, Alisoun Carey, Wendy Howard, Holly Shelton, Lorian Hartgroves, Kim Roberts, Manuela Mura, Lupita Ayora-Talavera, Elizabeth Townsend and Wendy Barclay. The past and current members of the ‘Flu group, for their constructive criticism and support. Guo Zhang, a tirelessly enthusiastic project student. The BBSRC for funding, Reading University for starting my doctorate and Imperial College for helping me finish it. Professor Barclay for her tireless support and encouragement, above and beyond the call of duty, then a little bit more. Liz & Lorian for listening, sympathising and laughing at all the right times. Mum, Alex & Anne-Marie, Love you, Thank you for everything. 3 Abstract Influenza B viruses encode two small proteins, NB and BM2. BM2 is translated from segment 7 mRNAs by a mechanism involving sequence complementarity to the 18S ribosomal subunit. The importance of these complementary sequences was tested in the context of infectious virus using a reverse genetic approach. A series of mutations were introduced into this region of segment 7. Recombinant viruses with disrupted 18S complementarity displayed deficiency in BM2 expression in infected cells. The BM2 protein is essential for virus replication because its ion channel activity is required during virion entry to the cell. There is also evidence that the cytoplasmic tail of BM2 is involved in viral assembly. A series of amino acid truncations and substitutions in the BM2 cytoplasmic tail were engineered. Recombinant viruses that lacked more than 5 residues at the carboxyl terminus of the protein were not recovered and key residues in the region -5 to -10 were identified. The influenza B virus RNA segment 6 encodes the neuraminidase protein, NA, as well as NB. NB is a 100 amino acid transmembrane protein with a glycosylated ectodomain. NB is conserved in all natural influenza B virus isolates. Influenza B viruses that lack the NB protein can replicate in cell culture to wild-type levels, However, the deletant viruses showed attenuated growth in complex airway cultures derived from humans and ferrets. In vivo, infected ferrets excreted infectious virus in the nasal wash one day later than for viruses that encode NB. Alterations in the expression of the NA protein were not responsible for the attenuated phenotype shown by NB deletant viruses. The role of the host cell ESCRT pathway or of the interferon-induced tetherin protein in assembly and release of influenza viruses was assessed. No evidence was found for either host pathway in the replication of influenza viruses. 4 Table of Contents Declaration .................................................................................................................................... 2 Acknowledgements ....................................................................................................................... 3 Abstract ......................................................................................................................................... 4 Table of Contents .......................................................................................................................... 5 Table of Figures ........................................................................................................................... 10 List of Tables ............................................................................................................................... 14 Chapter 1. Introduction .............................................................................................................. 15 1.1 The Orthomyxoviridae ..................................................................................................... 15 1.2 Influenza B classification .................................................................................................. 17 1.3 The influenza B replication Cycle ..................................................................................... 20 1.3.1 Attachment ................................................................................................................ 21 1.3.2 Cell Entry .................................................................................................................... 24 1.3.3 Fusion of the virus and endosomal membranes ...................................................... 25 1.3.4 Viral Uncoating and the Ion Channels ...................................................................... 26 1.3.5 Nuclear localisation ................................................................................................... 27 1.3.6 Non-Structural protein: NS-1 .................................................................................... 28 1.3.7 Replication ................................................................................................................. 29 1.3.8 Promoter Structures and compatibility .................................................................... 29 1.3.9 Polymerase interactions ........................................................................................... 31 1.3.10 mRNA, cRNA and vRNA ........................................................................................... 32 1.3.11 Dissociation from the nucleosome ......................................................................... 33 1.3.12 Export from the nucleus .......................................................................................... 33 1.3.13 Transport to the Apical membrane ........................................................................ 33 1.3.14 Glycoproteins and the Trans Golgi Network (TGN) ............................................... 34 1.3.15 vRNP’s and the cytoskeleton .................................................................................. 34 1.4 ESCRT: Endosomal Sorting Complexes Required for Transport ...................................... 35 1.5 PA (Polymerase Acid) and assembly ................................................................................ 35 1.6 M1(matrix protein), glycoproteins and lipid rafts .......................................................... 36 1.7 Packaging Signals .............................................................................................................. 37 1.8 The Ion Channel Reprise: AM2 and BM2 role in assembly ............................................. 38 1.9 AM2 in viral dissemination .............................................................................................. 39 1.10 The actions of neuraminidase ........................................................................................ 39 5 1.11 The NB and CM2 Proteins. ............................................................................................. 40 1.12 The impact of Influenza B and Vaccine production. ..................................................... 41 1.13 Animal models in the study of influenza virus .............................................................. 45 1.14 Reverse Genetics ............................................................................................................ 48 1.15 Thesis Aims ..................................................................................................................... 51 Chapter 2. Modifications in regions complementary to the 18S ribosomal subunit upstream of the BM2 initiation codon affect protein production .................................................................. 53 2.1 Introduction ...................................................................................................................... 53 2.2 Results .............................................................................................................................. 62 2.2.1 Design of influenza B virus mutants with altered complementarity to the 18S Ribosome in the segment 7 mRNA. ....................................................................................... 62 2.2.2 Analysis of BM2expression from influenza B virus segment 7 mRNA mutants with altered complementarity to the 18S Ribosome. ................................................................... 63 2.2.3 Analysis of BM2 expression by recombinant influenza B virus mutants with altered complementarity to the 18S Ribosome in the segment 7 mRNA in the virally infected cell. ................................................................................................................................................ 66 2.2.4 Phenotype of recombinant viruses with altered BM2 expression. ............................. 70 2.3 Discussion ........................................................................................................................ 72 Chapter 3. The reverse genetic manipulation of the BM2 cytoplasmic tail ............................... 77 3.1 Introduction: Influenza B virus BM2 protein ................................................................... 77 3.2 Results: ............................................................................................................................
Load more

Recommended publications
  • Emerging Role of Mucosal Vaccine in Preventing Infection with Avian Influenza a Viruses
    viruses Review Emerging Role of Mucosal Vaccine in Preventing Infection with Avian Influenza A Viruses Tong Wang 1, Fanhua Wei 2 and Jinhua Liu 1,* 1 Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; [email protected] 2 College of Agriculture, Ningxia University, Yinchuan 750021, China; [email protected] * Correspondence: [email protected] Received: 22 July 2020; Accepted: 5 August 2020; Published: 7 August 2020 Abstract: Avian influenza A viruses (AIVs), as a zoonotic agent, dramatically impacts public health and the poultry industry. Although low pathogenic avian influenza virus (LPAIV) incidence and mortality are relatively low, the infected hosts can act as a virus carrier and provide a resource pool for reassortant influenza viruses. At present, vaccination is the most effective way to eradicate AIVs from commercial poultry. The inactivated vaccines can only stimulate humoral immunity, rather than cellular and mucosal immune responses, while failing to effectively inhibit the replication and spread of AIVs in the flock. In recent years, significant progresses have been made in the understanding of the mechanisms underlying the vaccine antigen activities at the mucosal surfaces and the development of safe and efficacious mucosal vaccines that mimic the natural infection route and cut off the AIVs infection route. Here, we discussed the current status and advancement on mucosal immunity, the means of establishing mucosal immunity, and finally a perspective for design of AIVs mucosal vaccines. Hopefully, this review will help to not only understand and predict AIVs infection characteristics in birds but also extrapolate them for distinction or applicability in mammals, including humans.
    [Show full text]
  • Development and Effects of Influenza Antiviral Drugs
    molecules Review Development and Effects of Influenza Antiviral Drugs Hang Yin, Ning Jiang, Wenhao Shi, Xiaojuan Chi, Sairu Liu, Ji-Long Chen and Song Wang * Key Laboratory of Fujian-Taiwan Animal Pathogen Biology, College of Animal Sciences (College of Bee Science), Fujian Agriculture and Forestry University, Fuzhou 350002, China; [email protected] (H.Y.); [email protected] (N.J.); [email protected] (W.S.); [email protected] (X.C.); [email protected] (S.L.); [email protected] (J.-L.C.) * Correspondence: [email protected] Abstract: Influenza virus is a highly contagious zoonotic respiratory disease that causes seasonal out- breaks each year and unpredictable pandemics occasionally with high morbidity and mortality rates, posing a great threat to public health worldwide. Besides the limited effect of vaccines, the problem is exacerbated by the lack of drugs with strong antiviral activity against all flu strains. Currently, there are two classes of antiviral drugs available that are chemosynthetic and approved against influenza A virus for prophylactic and therapeutic treatment, but the appearance of drug-resistant virus strains is a serious issue that strikes at the core of influenza control. There is therefore an urgent need to develop new antiviral drugs. Many reports have shown that the development of novel bioactive plant extracts and microbial extracts has significant advantages in influenza treat- ment. This paper comprehensively reviews the development and effects of chemosynthetic drugs, plant extracts, and microbial extracts with influenza antiviral activity, hoping to provide some refer- ences for novel antiviral drug design and promising alternative candidates for further anti-influenza drug development.
    [Show full text]
  • OPTIONS X Programme
    Options X for the Control of Influenza | WELCOME MESSAGES BREAKTHROUGH INFLUENZA VACCINES TAKE LARGE DOSES OF INNOVATION Protecting people from the ever-changing threat of influenza takes unwavering commitment. That’s why we’re dedicated to developing advanced technologies and vaccines that can fight influenza as it evolves. We’re with you. ON THE FRONT LINETM BREAKTHROUGH INFLUENZA VACCINES TAKE LARGE DOSES OF INNOVATION CONTENT OPTIONS X SUPPORTERS ------------------- 4 OPTIONS X EXHIBITORS & COMMITTEES ------------------- 5 AWARD INFORMATION ------------------- 6 WELCOME MESSAGES ------------------- 7 SCHEDULE AT A GLANCE ------------------- 10 CONFERENCE INFORMATION ------------------- 11 SOCIAL PROGRAMME ------------------- 14 ABOUT SINGAPORE ------------------- 15 SUNTEC FLOORPLAN ------------------- 16 SCIENTIFIC COMMUNICATIONS ------------------- 17 PROGRAMME ------------------- 19 SPEAKERS ------------------- 31 SPONSORED SYMPOSIA ------------------- 39 ORAL PRESENTATION LISTINGS ------------------- 42 POSTER PRESENTATION LISTINGS ------------------- 51 ABSTRACTS POSTER DISPLAY LISTINGS ------------------- 54 SPONSOR AND EXHIBITOR LISTINGS ------------------- 80 EXHIBITION FLOORPLAN ------------------- 83 Protecting people from the ever-changing threat of NOTE ------------------- 84 influenza takes unwavering commitment. That’s why we’re dedicated to developing advanced technologies and vaccines that can fight influenza as it evolves. We’re with you. ON THE FRONT LINETM Options X for the Control of Influenza | OPTIONS X SUPPORTERS
    [Show full text]
  • Bin Brook Easter 2018
    Bin Brook Draft 4 AW.qxp_Layout 1 01/08/2018 13:48 Page 1 BIN EASTER 2018 BROOK ROBINSON COLLEGE UNIVERSITY OF CAMBRIDGE Diversifying Robinson Bringing Focus on Medicine From bats to Travels with our students India Remembering Robinson the brightest and best to Cambridge herpes with Robinson's medics and Iraq with Zhuan and Molly Dr Mary Stewart's living legacy Bin Brook Draft 4 AW.qxp_Layout 1 01/08/2018 13:48 Page 2 02 Contents WELCOME 03 News in brief 04 Diversifying Robinson Bin Brook is Robinson’s flagship publication, keeping our alumni and friends 05 Access to Robinson Eleanor Humphrey in touch with the College and with each other. In view of its importance 06 My Robinson Dr Ben Guy we felt it was owed a facelift, and we hope you like the new look. 07 e Cancer Problem Dr Gary Doherty 08 Must all that lives die? Dr Anke Timmerman Easter 2018 is the first in a series of themed issues, focusing this time on the ground- breaking work of our Fellows in Medicine. ere can be few of us whose lives have 09 Fighting fluProfessor Wendy Barclay been untouched by illnesses such as cancer, viral disease or dementia, and it’s exciting to see that the research that may change the direction of our approaches 10 Bats in the limelight Dr Oliver Restif to these modern-day plagues may come out of Robinson. 11 Learning about memory Dr Brian McCabe Oxbridge admissions have been in the media spotlight recently and we are pleased to offer an 12 Brain Training Dr Duncan Astle insight into our outreach work, answering some of our readers’ questions on this most important 13 e Medic’s Tale Oliver Fox subject that is so close to Robinson’s heart and heritage.
    [Show full text]
  • The Future of Vaccination the FUTURE of VACCINATION the FUTURE of VACCINATION
    The future of vaccination THE FUTURE OF VACCINATION THE FUTURE OF VACCINATION Vaccines are one of the greatest triumphs in modern medicine, saving up to 3m lives each year. They are widely regarded as the single most cost-effective public health intervention: every dollar spent on childhood immunisations in Africa returns $44 in economic benefits. We mostly think of vaccines as a way of protecting against communicable (infectious) childhood diseases such as measles. Professor Robin Shattock, In fact, vaccines are far more versatile. They offer hope for Professor Wendy Barclay combating HIV as well as non-communicable diseases such and Professor Jason Hallett as cancer and Alzheimer’s disease, due in part to the presented their research to development of DNA and RNA vaccination techniques. the World Economic Forum in Davos. Fast-tracked vaccines have the potential to contain disease outbreaks before they escalate into epidemics or pandemics. Such research offers the opportunity to innovate in science Vaccines can also target antimicrobial resistance (AMR), and manufacturing; to save lives; enhance wellbeing; and a growing threat that jeopardises hard-won gains in public even to safeguard the future of humanity. health and could claim as many as 10m lives annually by 2050. The feature includes interviews with academics in the cross- This feature offers a broad overview on vaccines, covering disciplinary Imperial Network for Vaccine Research, and other the following five areas: researchers and policymakers. These interviews focus on future vaccine research and the policy changes needed to maximise • what is a vaccine and how does it work? the benefits of that research.
    [Show full text]
  • The Impact of NMR and MRI
    WELLCOME WITNESSES TO TWENTIETH CENTURY MEDICINE _____________________________________________________________________________ MAKING THE HUMAN BODY TRANSPARENT: THE IMPACT OF NUCLEAR MAGNETIC RESONANCE AND MAGNETIC RESONANCE IMAGING _________________________________________________ RESEARCH IN GENERAL PRACTICE __________________________________ DRUGS IN PSYCHIATRIC PRACTICE ______________________ THE MRC COMMON COLD UNIT ____________________________________ WITNESS SEMINAR TRANSCRIPTS EDITED BY: E M TANSEY D A CHRISTIE L A REYNOLDS Volume Two – September 1998 ©The Trustee of the Wellcome Trust, London, 1998 First published by the Wellcome Trust, 1998 Occasional Publication no. 6, 1998 The Wellcome Trust is a registered charity, no. 210183. ISBN 978 186983 539 1 All volumes are freely available online at www.history.qmul.ac.uk/research/modbiomed/wellcome_witnesses/ Please cite as : Tansey E M, Christie D A, Reynolds L A. (eds) (1998) Wellcome Witnesses to Twentieth Century Medicine, vol. 2. London: Wellcome Trust. Key Front cover photographs, L to R from the top: Professor Sir Godfrey Hounsfield, speaking (NMR) Professor Robert Steiner, Professor Sir Martin Wood, Professor Sir Rex Richards (NMR) Dr Alan Broadhurst, Dr David Healy (Psy) Dr James Lovelock, Mrs Betty Porterfield (CCU) Professor Alec Jenner (Psy) Professor David Hannay (GPs) Dr Donna Chaproniere (CCU) Professor Merton Sandler (Psy) Professor George Radda (NMR) Mr Keith (Tom) Thompson (CCU) Back cover photographs, L to R, from the top: Professor Hannah Steinberg, Professor
    [Show full text]
  • Virus-Host Interactomics: New Insights and Opportunities for Antiviral Drug Discovery
    de Chassey et al. Genome Medicine 2014, 6:115 http://genomemedicine.com/content/6/11/115 REVIEW Virus-host interactomics: new insights and opportunities for antiviral drug discovery Benoît de Chassey1, Laurène Meyniel-Schicklin1, Jacky Vonderscher1, Patrice André2,3,4 and Vincent Lotteau3,4* Abstract The current therapeutic arsenal against viral infections remains limited, with often poor efficacy and incomplete coverage, and appears inadequate to face the emergence of drug resistance. Our understanding of viral biology and pathophysiology and our ability to develop a more effective antiviral arsenal would greatly benefit from a more comprehensive picture of the events that lead to viral replication and associated symptoms. Towards this goal, the construction of virus-host interactomes is instrumental, mainly relying on the assumption that a viral infection at the cellular level can be viewed as a number of perturbations introduced into the host protein network when viral proteins make new connections and disrupt existing ones. Here, we review advances in interactomic approaches for viral infections, focusing on high-throughput screening (HTS) technologies and on the generation of high-quality datasets. We show how these are already beginning to offer intriguing perspectives in terms of virus-host cell biology and the control of cellular functions, and we conclude by offering a summary of the current situation regarding the potential development of host-oriented antiviral therapeutics. Introduction the virus life-cycle. These proteins
    [Show full text]
  • Mutations That Adapt SARS-Cov-2 to Mustelid Hosts Do Not Increase Tness in the Human Airway
    Mutations that adapt SARS-CoV-2 to mustelid hosts do not increase tness in the human airway. Jie Zhou Imperial College London Thomas Peacock ( [email protected] ) Department of Infectious Disease, Imperial College London https://orcid.org/0000-0001-7077-2928 Jonathan Brown Imperial College London https://orcid.org/0000-0001-6849-3962 Daniel Goldhill Department of Infectious Disease, Imperial College London Ahmed Elrefaey The Pirbright Instiute Rebekah Penrice-Randal Institute of Infection, Veterinary and Ecology Sciences, University of Liverpool, UK Vanessa Cowton University of Glasgow https://orcid.org/0000-0003-1813-7825 Giuditta De Lorenzo MRC-University of Glasgow Wilhelm Furnon MRC-University of Glasgow Centre for Virus Research, Glasgow, UK William Harvey MRC-University of Glasgow Centre for Virus Research, Glasgow, UK Ruthiran Kugathasan Department of Infectious Diseases, Imperial College London, UK, Rebecca Frise Imperial College London Laury Baillon Department of Infectious Diseases, Imperial College London, UK, Ria Lassauniere Statens Serum https://orcid.org/0000-0002-3910-7185 Nazia Thakur The Pirbright Institute https://orcid.org/0000-0002-4450-5911 Giulia Gallo The Pirbright Institute, Woking, Surrey, UK, Hannah Goldswain Institute of Infection, Veterinary and Ecology Sciences, University of Liverpool, UK I'ah Donovan-Baneld Institute of Infection, Veterinary and Ecology Sciences, University of Liverpool, UK Xiaofeng Dong Liverpool Univ Nadine Randle University of Liverpool Fiachra Sweeney Department of Infectious
    [Show full text]
  • Antiviral Drug Baloxavir Reduces Transmission of Flu Virus Among Ferrets 15 April 2020
    Antiviral drug baloxavir reduces transmission of flu virus among ferrets 15 April 2020 licensed antiviral drug called baloxavir has been shown to reduce the amount of virus particles produced by infected people more effectively than the widely used drug oseltamivir. In the new study, the researchers tested whether baloxavir treatment might also interrupt onward virus transmission. They found that baloxavir treatment reduced infectious viral shedding in the upper respiratory tract of ferrets infected with A(H1N1)pdm09 influenza viruses compared to placebo, and reduced the frequency of transmission, even when treatment was delayed until two days after infection. By contrast, oseltamivir treatment did not substantially affect viral shedding or transmission Credit: CC0 Public Domain compared to placebo. Importantly, the researchers did not detect the emergence of baloxavir-resistant variants in the animals. The results support the idea that antivirals which decrease viral shedding could Baloxavir treatment reduced transmission of the flu also reduce influenza transmission in the virus from infected ferrets to healthy ferrets, community. According to the authors, such an suggesting that the antiviral drug could contribute effect has the potential to dramatically change how to the early control of influenza outbreaks by we manage influenza outbreaks, including limiting community-based viral spread, according pandemic influenza. to a study published April 15 in the open-access journal PLOS Pathogens by Aeron Hurt of F. The authors add, "Our study shows that baloxavir Hoffmann-La Roche Ltd and Wendy Barclay of can have a dual effect in influenza: a single dose Imperial College London, and colleagues. As noted reduces the symptoms and reduces the risk of by the authors, this is the first evidence that the passing it on to others as well".
    [Show full text]
  • Influenza: a Seasonal Disease
    Influenza: A seasonal disease FACTFILE Influenza: A seasonal disease nfluenza or ‘flu’ is a common viral addition, global influenza pandemics proteins that the virus needs in order disease of the upper respiratory tract have been recorded throughout history to replicate inside the infected host cell. Iin humans (in birds it is an infection and they seem to occur every 10 to 40 The genome is protected by a membrane of the gut). There are three types of years. Between 1918 and 1919 flu is envelope. Protruding from the virus influenza virus: influenza A, B and C. thought to have killed over 50 million membrane are hundreds of copies of two However, a fourth type, influenza D, people (6 times as many as died as a different varieties of viral glycoprotein has recently been discovered as a consequence of the first-world war). It spikes. Approximately 80% of the veterinary infection, particularly of was caused by an unusually pathogenic spikes are haemagglutinin (HA) and the cows. Major outbreaks of influenza are strain of influenza A virus. remaining 20% are neuraminidase (NA). associated with influenza virus type A The HA and NA surface proteins are or B. Influenza C is common but seldom What causes flu? involved in viral attachment and entry causes disease The influenza virus particle – virion to host cells as well as the release of Influenza A is commonly associated – is usually spherical, but sometimes new virions. They are also the main part with human disease. Each year, many filamentous, in shape and carries its of the virus recognised by our immune countries, including the UK, experience genetic material on eight pieces of single system as foreign, and most of the seasonal influenza epidemics that affect stranded RNA known as segments.
    [Show full text]
  • To Download a Copy of Agencyiq's COVID-19 Development Tracker
    Development tracker: The drugs and vaccines in development for COVID-19 The pharmaceutical and biopharmaceutical industry is scrambling to put products into development to potentially treat, cure or prevent COVID-19 infections. Based on a review by AgencyIQ of ClinicalTrials.gov, company announcements and media reports, there are at least 140 medical product candidates in various stages of testing to assess their potential effects against COVID-19 or SARS-CoV-2, the virus which causes the condition. Some have already been approved and are being assessed for their potential to treat COVID, while others are being repurposed from other late-stage development pipelines. Others are still in the very early stages of development and have not yet been tested in humans. Based on evidence from recent studies, the chances of clinical success are low. Of all drugs for infectious diseases that enter Phase 1 testing, just 26.7% go on to obtain approval. Just 31.6% of vaccines that enter Phase 1 testing go on to obtain approval. The size of the development pipeline and interest in COVID-19 may indicate that several of these products will go on to obtain approval, but the safety and efficacy of these products is far from guaranteed. As companies try to bring whatever compounds they have into clinical testing, it’s possible that few, if any, of these products will ultimately prove safe or effective. Highlights: 95+ 45+ 24+ 40+ Therapeutic medical Vaccines in development Products already approved Products already in clinical products in development for other indications development (6 vaccines, 34 therapies) Last updated 8 April 2020.
    [Show full text]
  • Influenza a Virus Superinfection Potential Is Regulated by Viral
    bioRxiv preprint doi: https://doi.org/10.1101/286070; this version posted March 21, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Influenza A virus superinfection potential is regulated 2 by viral genomic heterogeneity 3 4 Jiayi Sun1 and Christopher B. Brooke1,2* 5 6 1Department of Microbiology; University of Illinois, Urbana, IL 61801 7 2Carl R. Woese Institute for Genomic Biology; University of Illinois, Urbana, IL 61801 8 *Corresponding author ([email protected]) 9 10 Abstract 11 12 Defining the specific factors that govern the evolution and transmission of influenza A 13 virus (IAV) populations is of critical importance for designing more effective prediction and 14 control strategies. Superinfection, the sequential infection of a single cell by two or more 15 virions, plays an important role in determining the replicative and evolutionary potential of 16 IAV populations. The prevalence of superinfection during natural infection, and the 17 specific mechanisms that regulate it, remain poorly understood. Here, we used a novel 18 single virion infection approach to directly assess the effects of individual IAV genes on 19 superinfection efficiency. Rather than implicating a specific viral gene, this approach 20 revealed that superinfection susceptibility is determined by the total number of viral genes 21 expressed, independent of their identity. IAV particles that expressed a complete set of 22 viral genes potently inhibit superinfection, while semi-infectious particles (SIPs) that 23 express incomplete subsets of viral genes do not. As a result, virus populations that 24 contain more SIPs undergo more frequent superinfection.
    [Show full text]