1
|
Quandelacy TM, Cummings DAT, Jiang CQ, Yang B, Kwok KO, Dai B, Shen R, Read JM, Zhu H, Guan Y, Riley S, Lessler J. Using serological measures to estimate influenza incidence in the presence of secular trends in exposure and immuno-modulation of antibody response. Influenza Other Respir Viruses 2021; 15:235-244. [PMID: 33108707 PMCID: PMC7902255 DOI: 10.1111/irv.12807] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/24/2020] [Accepted: 08/30/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Influenza infection is often measured by a fourfold antibody titer increase over an influenza season (ie seroconversion). However, this approach may fail when influenza seasons are less distinct as it does not account for transient effects from recent infections. Here, we present a method to determine seroconversion for non-paired sera, adjusting for changes in individuals' antibody titers to influenza due to the transient impact of recent exposures, varied sampling times, and laboratory processes. METHODS We applied our method using data for five H3N2 strains collected from 942 individuals, aged 2-90 years, during the first two study visits of the Fluscape cohort study (2009-2012) in Guangzhou, China. RESULTS After adjustment, apparent seroconversion rates for non-circulating strains decreased while we observed a 20% increase in seroconversion rates to recently circulating strains. When examining seroconversion to the most recently circulating strain (A/Brisbane/20/2007) in our study, participants aged under 18, and over 64 had the highest seroconversion rates compared to other age groups. CONCLUSIONS Our results highlight the need for improved methods when using antibody titers as an endpoint in settings where there is no clear influenza "off" season. Methods, like those presented here, that use titers from circulating and non-circulating strains may be key.
Collapse
Affiliation(s)
- Talia M. Quandelacy
- Department of EpidemiologyJohns Hopkins Bloomberg School of Public HealthBaltimoreMDUSA
- Present address:
Centers for Disease Control and PreventionSan JuanPuerto Rico
| | - Derek A. T. Cummings
- Department of EpidemiologyJohns Hopkins Bloomberg School of Public HealthBaltimoreMDUSA
- Department of BiologyUniversity of FloridaGainesvilleFLUSA
| | | | - Bingyi Yang
- Department of BiologyUniversity of FloridaGainesvilleFLUSA
| | - Kin On Kwok
- The Jockey Club School of Public Health and Primary CareThe Chinese University of Hong KongHong Kong Special Administrative RegionChina
- Stanley Ho Centre for Emerging Infectious DiseasesHong Kong Special Administrative RegionThe Chinese University of Hong KongShatin, Hong KongChina
- Shenzhen Research InstituteThe Chinese University of Hong KongShenzhenChina
| | - Byran Dai
- Department of EpidemiologyJohns Hopkins Bloomberg School of Public HealthBaltimoreMDUSA
| | | | - Jonathan M. Read
- Center for Health Informatics Computing and StatisticsLancaster Medical SchoolLancaster UniversityLancasterUK
- Institute of Infection and Global HealthUniversity of LiverpoolLiverpoolUK
| | - Huachen Zhu
- State Key Laboratory of Emerging Infectious DiseasesSchool of Public HealthThe University of Hong KongHong KongChina
- Shantou University Medical CollegeShantouChina
| | - Yi Guan
- Shantou University Medical CollegeShantouChina
- School of Public HealthImperial College LondonLondonUK
| | - Steven Riley
- School of Public HealthImperial College LondonLondonUK
| | - Justin Lessler
- Department of EpidemiologyJohns Hopkins Bloomberg School of Public HealthBaltimoreMDUSA
| |
Collapse
|
2
|
Yang B, Lessler J, Zhu H, Jiang CQ, Read JM, Hay JA, Kwok KO, Shen R, Guan Y, Riley S, Cummings DAT. Life course exposures continually shape antibody profiles and risk of seroconversion to influenza. PLoS Pathog 2020; 16:e1008635. [PMID: 32702069 PMCID: PMC7377380 DOI: 10.1371/journal.ppat.1008635] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/14/2020] [Indexed: 12/05/2022] Open
Abstract
Complex exposure histories and immune mediated interactions between influenza strains contribute to the life course of human immunity to influenza. Antibody profiles can be generated by characterizing immune responses to multiple antigenically variant strains, but how these profiles vary across individuals and determine future responses is unclear. We used hemagglutination inhibition titers from 21 H3N2 strains to construct 777 paired antibody profiles from people aged 2 to 86, and developed novel metrics to capture features of these profiles. Total antibody titer per potential influenza exposure increases in early life, then decreases in middle age. Increased titers to one or more strains were seen in 97.8% of participants during a roughly four-year interval, suggesting widespread influenza exposure. While titer changes were seen to all strains, recently circulating strains exhibited the greatest titer rise. Higher pre-existing, homologous titers at baseline reduced the risk of seroconversion to recent strains. After adjusting for homologous titer, we also found an increased frequency of seroconversion against recent strains among those with higher immunity to older previously exposed strains. Including immunity to previously exposures also improved the deviance explained by the models. Our results suggest that a comprehensive quantitative description of immunity encompassing past exposures could lead to improved correlates of risk of influenza infection.
Collapse
Affiliation(s)
- Bingyi Yang
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Huachen Zhu
- State Key Laboratory of Emerging Infectious Diseases and Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China
- Joint Institute of Virology (Shantou University–The University of Hong Kong), Shantou University, Shantou, Guangdong, China
| | | | - Jonathan M. Read
- Centre for Health Informatics Computing and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - James A. Hay
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Kin On Kwok
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
- Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region, China
- Shenzhen Research Institute of The Chinese University of Hong Kong, Shenzhen, Guangdong, China
| | - Ruiyin Shen
- Guangzhou No.12 Hospital, Guangzhou, Guangdong, China
| | - Yi Guan
- State Key Laboratory of Emerging Infectious Diseases and Centre of Influenza Research, School of Public Health, The University of Hong Kong, Hong Kong SAR, China
- Joint Institute of Virology (Shantou University–The University of Hong Kong), Shantou University, Shantou, Guangdong, China
| | - Steven Riley
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Derek A. T. Cummings
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| |
Collapse
|
3
|
Temte JL, Uzicanin A, Goss M, Comp L, Temte E, Barlow S, Reisdorf E, Shult P, Wedig M, Florek K. Sequential, within-season infection with influenza A (H3N2) in a usually healthy vaccinated child. Influenza Other Respir Viruses 2019; 13:528-531. [PMID: 32744798 PMCID: PMC6692547 DOI: 10.1111/irv.12668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 11/27/2022] Open
Abstract
Cocirculation of varying influenza types, strains, and lineages allows coinfection and intra-season sequential infection, although a same-strain sequential infection has not been previously described. This case report describes the first known case of sequential laboratory-confirmed influenza A (H3N2) infections in a child within one season.
Collapse
Affiliation(s)
| | - Amra Uzicanin
- Centers for Disease Control and PreventionAtlantaGeorgiaUSA
| | | | - Lily Comp
- University of WisconsinMadisonWisconsinUSA
| | | | | | - Erik Reisdorf
- Wisconsin State Laboratory of HygieneMadisonWisconsinUSA
| | - Peter Shult
- Wisconsin State Laboratory of HygieneMadisonWisconsinUSA
| | - Mary Wedig
- Wisconsin State Laboratory of HygieneMadisonWisconsinUSA
| | - Kelsey Florek
- Wisconsin State Laboratory of HygieneMadisonWisconsinUSA
| |
Collapse
|
4
|
Lam HM, Wesolowski A, Hung NT, Nguyen TD, Nhat NTD, Todd S, Vinh DN, Vy NHT, Thao TTN, Thanh NTL, Tin PT, Minh NNQ, Bryant JE, Buckee CO, Ngoc TV, Chau NVV, Thwaites GE, Farrar J, Tam DTH, Vinh H, Boni MF. Nonannual seasonality of influenza-like illness in a tropical urban setting. Influenza Other Respir Viruses 2018; 12:742-754. [PMID: 30044029 PMCID: PMC6185894 DOI: 10.1111/irv.12595] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND In temperate and subtropical climates, respiratory diseases exhibit seasonal peaks in winter. In the tropics, with no winter, peak timings are irregular. METHODS To obtain a detailed picture of influenza-like illness (ILI) patterns in the tropics, we established an mHealth study in community clinics in Ho Chi Minh City (HCMC). During 2009-2015, clinics reported daily case numbers via SMS, with a subset performing molecular diagnostics for influenza virus. This real-time epidemiology network absorbs 6000 ILI reports annually, one or two orders of magnitude more than typical surveillance systems. A real-time online ILI indicator was developed to inform clinicians of the daily ILI activity in HCMC. RESULTS From August 2009 to December 2015, 63 clinics were enrolled and 36 920 SMS reports were received, covering approximately 1.7M outpatient visits. Approximately 10.6% of outpatients met the ILI case definition. ILI activity in HCMC exhibited strong nonannual dynamics with a dominant periodicity of 206 days. This was confirmed by time series decomposition, stepwise regression, and a forecasting exercise showing that median forecasting errors are 30%-40% lower when using a 206-day cycle. In ILI patients from whom nasopharyngeal swabs were taken, 31.2% were positive for influenza. There was no correlation between the ILI time series and the time series of influenza, influenza A, or influenza B (all P > 0.15). CONCLUSION This suggests, for the first time, that a nonannual cycle may be an essential driver of respiratory disease dynamics in the tropics. An immunological interference hypothesis is discussed as a potential underlying mechanism.
Collapse
Affiliation(s)
- Ha Minh Lam
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Amy Wesolowski
- Center for Communicable Disease DynamicsDepartment of EpidemiologyHarvard T.H. Chan School of Public HealthBostonMassachusetts
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew Jersey
| | - Nguyen Thanh Hung
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Tran Dang Nguyen
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Thi Duy Nhat
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Stacy Todd
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Liverpool School of Tropical MedicineLiverpoolUK
| | - Dao Nguyen Vinh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Ha Thao Vy
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Tran Thi Nhu Thao
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Nguyen Thi Le Thanh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | | | - Ngo Ngoc Quang Minh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Children's Hospital No. 1Ho Chi Minh CityVietnam
| | - Juliet E. Bryant
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Caroline O. Buckee
- Center for Communicable Disease DynamicsDepartment of EpidemiologyHarvard T.H. Chan School of Public HealthBostonMassachusetts
| | - Tran Van Ngoc
- Hospital for Tropical DiseasesHo Chi Minh CityVietnam
| | | | - Guy E. Thwaites
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Jeremy Farrar
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Wellcome TrustLondonUK
| | - Dong Thi Hoai Tam
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
| | - Ha Vinh
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Hospital for Tropical DiseasesHo Chi Minh CityVietnam
- Department of Infectious DiseasesPham Ngoc Thach University of MedicineHo Chi Minh CityVietnam
| | - Maciej F. Boni
- Oxford University Clinical Research UnitWellcome Trust Major Overseas ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
- Center for Infectious Disease DynamicsDepartment of BiologyPennsylvania State UniversityUniversity ParkPennsylvania
| |
Collapse
|
5
|
Kucharski AJ, Lessler J, Cummings DAT, Riley S. Timescales of influenza A/H3N2 antibody dynamics. PLoS Biol 2018; 16:e2004974. [PMID: 30125272 PMCID: PMC6117086 DOI: 10.1371/journal.pbio.2004974] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 08/30/2018] [Accepted: 08/07/2018] [Indexed: 11/18/2022] Open
Abstract
Human immunity influences the evolution and impact of influenza strains. Because individuals are infected with multiple influenza strains during their lifetime, and each virus can generate a cross-reactive antibody response, it is challenging to quantify the processes that shape observed immune responses or to reliably detect recent infection from serological samples. Using a Bayesian model of antibody dynamics at multiple timescales, we explain complex cross-reactive antibody landscapes by inferring participants' histories of infection with serological data from cross-sectional and longitudinal studies of influenza A/H3N2 in southern China and Vietnam. We find that individual-level influenza antibody profiles can be explained by a short-lived, broadly cross-reactive response that decays within a year to leave a smaller long-term response acting against a narrower range of strains. We also demonstrate that accounting for dynamic immune responses alongside infection history can provide a more accurate alternative to traditional definitions of seroconversion for the estimation of infection attack rates. Our work provides a general model for quantifying aspects of influenza immunity acting at multiple timescales based on contemporary serological data and suggests a two-armed immune response to influenza infection consistent with competitive dynamics between B cell populations. This approach to analysing multiple timescales for antigenic responses could also be applied to other multistrain pathogens such as dengue and related flaviviruses.
Collapse
Affiliation(s)
- Adam J. Kucharski
- Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Derek A. T. Cummings
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Steven Riley
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| |
Collapse
|
6
|
Koh WM, Badaruddin H, La H, Chen MIC, Cook AR. Severity and burden of hand, foot and mouth disease in Asia: a modelling study. BMJ Glob Health 2018; 3:e000442. [PMID: 29564154 PMCID: PMC5859810 DOI: 10.1136/bmjgh-2017-000442] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/08/2017] [Accepted: 10/11/2017] [Indexed: 11/04/2022] Open
Abstract
Background Hand, foot and mouth disease (HFMD) affects millions of children across Asia annually, leading to an increase in implemented control policies such as surveillance, isolation and social distancing in affected jurisdictions. However, limited knowledge of disease burden and severity causes difficulty in policy optimisation as the associated economic cost cannot be easily estimated. We use a data synthesis approach to provide a comprehensive picture of HFMD disease burden, estimating infection risk, symptomatic rates, the risk of complications and death, and overall disability-adjusted life-year (DALY) losses, along with associated uncertainties. Methods Complementary data from a variety of sources were synthesised with mathematical models to obtain estimates of severity of HFMD. This includes serological and other data extracted through a systematic review of HFMD epidemiology previously published by the authors, and laboratory investigations and sentinel reports from Singapore's surveillance system. Results HFMD is estimated to cause 96 900 (95% CI 40 600 to 259 000) age-weighted DALYs per annum in eight high-burden countries in East and Southeast Asia, with the majority of DALYs attributed to years of life lost. The symptomatic case hospitalisation rate of HFMD is 6% (2.8%-14.9%), of which 18.7% (6.7%-31.5%) are expected to develop complications. 5% (2.9%-7.4%) of such cases are fatal, bringing the overall case fatality ratio to be 52.3 (24.4-92.7) per 100 000 symptomatic infections. In contrast, the EV-A71 case fatality ratio is estimated to be at least 229.7 (75.4-672.1) per 100 000 symptomatic cases. Asymptomatic rate for EV-A71 is 71.4% (68.3%-74.3%) for ages 1-4, the years of greatest incidence. Conclusion Despite the high incidence rate of HFMD, total DALY due to HFMD is limited in comparison to other endemic diseases in the region, such as dengue and upper respiratory tract infection. With the majority of DALY caused by years of life lost, it is possible to mitigate most with increased EV-A71 vaccine coverage.
Collapse
Affiliation(s)
- Wee Ming Koh
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| | | | - Hanh La
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| | - Mark I-Cheng Chen
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore.,Communicable Disease Centre, Tan Tock Seng Hospital, Singapore
| | - Alex R Cook
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| |
Collapse
|
7
|
Zhao X, Ning Y, Chen MIC, Cook AR. Individual and Population Trajectories of Influenza Antibody Titers Over Multiple Seasons in a Tropical Country. Am J Epidemiol 2018; 187:135-143. [PMID: 29309522 PMCID: PMC5860523 DOI: 10.1093/aje/kwx201] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 03/06/2017] [Indexed: 01/15/2023] Open
Abstract
Seasonal influenza epidemics occur year-round in the tropics, complicating the planning of vaccination programs. We built an individual-level longitudinal model of baseline antibody levels, time of infection, and the subsequent rise and decay of antibodies postinfection using influenza A(H1N1)pdm09 data from 2 sources in Singapore: 1) a noncommunity cohort with real-time polymerase chain reaction–confirmed infections and at least 1 serological sample collected from each participant between May and October 2009 (n = 118) and 2) a community cohort with up to 6 serological samples collected between May 2009 and October 2010 (n = 760). The model was hierarchical, to account for interval censoring and interindividual variation. Model parameters were estimated via a reversible jump Markov chain Monte Carlo algorithm using custom-designed R (https://www.r-project.org/) and C++ (https://isocpp.org/) code. After infection, antibody levels peaked at 4–7 weeks, with a half-life of 26.5 weeks, followed by a slower decrease up to 1 year to approximately preinfection levels. After the third wave, the seropositivity rate and the population-level antibody titer dropped to the same level as they were at the end of the first pandemic wave. The results of this analysis are consistent with the hypothesis that the population-level effect of individuals’ waxing and waning antibodies influences influenza seasonality in the tropics.
Collapse
Affiliation(s)
- Xiahong Zhao
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| | - Yilin Ning
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Mark I-Cheng Chen
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
- Department of Clinical Epidemiology, Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore
| | - Alex R Cook
- Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore
| |
Collapse
|
8
|
Structure of general-population antibody titer distributions to influenza A virus. Sci Rep 2017; 7:6060. [PMID: 28729702 PMCID: PMC5519701 DOI: 10.1038/s41598-017-06177-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/09/2017] [Indexed: 12/24/2022] Open
Abstract
Seroepidemiological studies aim to understand population-level exposure and immunity to infectious diseases. Their results are normally presented as binary outcomes describing the presence or absence of pathogen-specific antibody, despite the fact that many assays measure continuous quantities. A population's natural distribution of antibody titers to an endemic infectious disease may include information on multiple serological states - naiveté, recent infection, non-recent infection, childhood infection - depending on the disease in question and the acquisition and waning patterns of immunity. In this study, we investigate 20,152 general-population serum samples from southern Vietnam collected between 2009 and 2013 from which we report antibody titers to the influenza virus HA1 protein using a continuous titer measurement from a protein microarray assay. We describe the distributions of antibody titers to subtypes 2009 H1N1 and H3N2. Using a model selection approach to fit mixture distributions, we show that 2009 H1N1 antibody titers fall into four titer subgroups and that H3N2 titers fall into three subgroups. For H1N1, our interpretation is that the two highest-titer subgroups correspond to recent and historical infection, which is consistent with 2009 pandemic attack rates. Similar interpretations are available for H3N2, but right-censoring of titers makes these interpretations difficult to validate.
Collapse
|
9
|
Vinh DN, Boni MF. Statistical identifiability and sample size calculations for serial seroepidemiology. Epidemics 2015; 12:30-9. [PMID: 26342240 PMCID: PMC4558460 DOI: 10.1016/j.epidem.2015.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 02/12/2015] [Accepted: 02/24/2015] [Indexed: 11/30/2022] Open
Abstract
We investigate whether disease dynamics can be inferred by repeated serum collections. Measuring antibody waning is critical for inference in serological time series. Collecting 200 samples every 2 months allows for inference of transmission parameters. Low-level seasonality is difficult to detect statistically.
Inference on disease dynamics is typically performed using case reporting time series of symptomatic disease. The inferred dynamics will vary depending on the reporting patterns and surveillance system for the disease in question, and the inference will miss mild or underreported epidemics. To eliminate the variation introduced by differing reporting patterns and to capture asymptomatic or subclinical infection, inferential methods can be applied to serological data sets instead of case reporting data. To reconstruct complete disease dynamics, one would need to collect a serological time series. In the statistical analysis presented here, we consider a particular kind of serological time series with repeated, periodic collections of population-representative serum. We refer to this study design as a serial seroepidemiology (SSE) design, and we base the analysis on our epidemiological knowledge of influenza. We consider a study duration of three to four years, during which a single antigenic type of influenza would be circulating, and we evaluate our ability to reconstruct disease dynamics based on serological data alone. We show that the processes of reinfection, antibody generation, and antibody waning confound each other and are not always statistically identifiable, especially when dynamics resemble a non-oscillating endemic equilibrium behavior. We introduce some constraints to partially resolve this confounding, and we show that transmission rates and basic reproduction numbers can be accurately estimated in SSE study designs. Seasonal forcing is more difficult to identify as serology-based studies only detect oscillations in antibody titers of recovered individuals, and these oscillations are typically weaker than those observed for infected individuals. To accurately estimate the magnitude and timing of seasonal forcing, serum samples should be collected every two months and 200 or more samples should be included in each collection; this sample size estimate is sensitive to the antibody waning rate and the assumed level of seasonal forcing.
Collapse
Affiliation(s)
- Dao Nguyen Vinh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Viet Nam
| | - Maciej F Boni
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Viet Nam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| |
Collapse
|
10
|
Affiliation(s)
- Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
| |
Collapse
|
11
|
Fonville JM, Wilks SH, James SL, Fox A, Ventresca M, Aban M, Xue L, Jones TC, Le NMH, Pham QT, Tran ND, Wong Y, Mosterin A, Katzelnick LC, Labonte D, Le TT, van der Net G, Skepner E, Russell CA, Kaplan TD, Rimmelzwaan GF, Masurel N, de Jong JC, Palache A, Beyer WEP, Le QM, Nguyen TH, Wertheim HFL, Hurt AC, Osterhaus ADME, Barr IG, Fouchier RAM, Horby PW, Smith DJ. Antibody landscapes after influenza virus infection or vaccination. Science 2014; 346:996-1000. [PMID: 25414313 PMCID: PMC4246172 DOI: 10.1126/science.1256427] [Citation(s) in RCA: 325] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We introduce the antibody landscape, a method for the quantitative analysis of antibody-mediated immunity to antigenically variable pathogens, achieved by accounting for antigenic variation among pathogen strains. We generated antibody landscapes to study immune profiles covering 43 years of influenza A/H3N2 virus evolution for 69 individuals monitored for infection over 6 years and for 225 individuals pre- and postvaccination. Upon infection and vaccination, titers increased broadly, including previously encountered viruses far beyond the extent of cross-reactivity observed after a primary infection. We explored implications for vaccination and found that the use of an antigenically advanced virus had the dual benefit of inducing antibodies against both advanced and previous antigenic clusters. These results indicate that preemptive vaccine updates may improve influenza vaccine efficacy in previously exposed individuals.
Collapse
Affiliation(s)
- J. M. Fonville
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - S. H. Wilks
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - S. L. James
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - A. Fox
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - M. Ventresca
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - M. Aban
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL at the Peter Doherty Institute for Infection and Immunity, Melbourne VIC 3000, Australia
| | - L. Xue
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL at the Peter Doherty Institute for Infection and Immunity, Melbourne VIC 3000, Australia
| | - T. C. Jones
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - N. M. H. Le
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
| | - Q. T. Pham
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - N. D. Tran
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - Y. Wong
- Oxford University Museum of Natural History, Oxford OX1 3PW, UK
| | - A. Mosterin
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - L. C. Katzelnick
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - D. Labonte
- Insect Biomechanics Group, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - T. T. Le
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - G. van der Net
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - E. Skepner
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
| | - C. A. Russell
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK
| | | | - G. F. Rimmelzwaan
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - N. Masurel
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - J. C. de Jong
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - A. Palache
- Abbott Laboratories, Weesp 1380 DA, the Netherlands
| | - W. E. P. Beyer
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - Q. M. Le
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - T. H. Nguyen
- National Institute of Hygiene and Epidemiology, Hanoi, Vietnam
| | - H. F. L. Wertheim
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - A. C. Hurt
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL at the Peter Doherty Institute for Infection and Immunity, Melbourne VIC 3000, Australia
- Melbourne School of Population and Global Health, University of Melbourne, Parkville VIC 3010, Australia
| | - A. D. M. E. Osterhaus
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - I. G. Barr
- WHO Collaborating Centre for Reference and Research on Influenza, VIDRL at the Peter Doherty Institute for Infection and Immunity, Melbourne VIC 3000, Australia
| | - R. A. M. Fouchier
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| | - P. W. Horby
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Hanoi, Vietnam
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - D. J. Smith
- Center for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- WHO Collaborating Center for Modeling, Evolution, and Control of Emerging Infectious Diseases, Cambridge CB2 3EJ, UK
- Department of Viroscience, Erasmus Medical Center, Rotterdam 3015 CE, the Netherlands
| |
Collapse
|
12
|
Lessler J, Riley S, Read JM, Wang S, Zhu H, Smith GJD, Guan Y, Jiang CQ, Cummings DAT. Evidence for antigenic seniority in influenza A (H3N2) antibody responses in southern China. PLoS Pathog 2012; 8:e1002802. [PMID: 22829765 PMCID: PMC3400560 DOI: 10.1371/journal.ppat.1002802] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Accepted: 06/01/2012] [Indexed: 11/19/2022] Open
Abstract
A key observation about the human immune response to repeated exposure to influenza A is that the first strain infecting an individual apparently produces the strongest adaptive immune response. Although antibody titers measure that response, the interpretation of titers to multiple strains – from the same sera – in terms of infection history is clouded by age effects, cross reactivity and immune waning. From July to September 2009, we collected serum samples from 151 residents of Guangdong Province, China, 7 to 81 years of age. Neutralization tests were performed against strains representing six antigenic clusters of H3N2 influenza circulating between 1968 and 2008, and three recent locally circulating strains. Patterns of neutralization titers were compared based on age at time of testing and age at time of the first isolation of each virus. Neutralization titers were highest for H3N2 strains that circulated in an individual's first decade of life (peaking at 7 years). Further, across strains and ages at testing, statistical models strongly supported a pattern of titers declining smoothly with age at the time a strain was first isolated. Those born 10 or more years after a strain emerged generally had undetectable neutralization titers to that strain (<1∶10). Among those over 60 at time of testing, titers tended to increase with age. The observed pattern in H3N2 neutralization titers can be characterized as one of antigenic seniority: repeated exposure and the immune response combine to produce antibody titers that are higher to more ‘senior’ strains encountered earlier in life. The human immune response to an influenza infection is not the same for every infection. It has often been observed that we tend to have the highest antibody titer (and presumably our strongest immune response) against strains of influenza that we were exposed to early in life. In this study, we obtained blood samples from 151 people between 7 and 81 years of age and tested the samples for the concentration of antibodies to many different (H3N2) strains. We chose strains according to when they first circulated, starting with a strain isolated just after the 1968 pandemic and going all the way through to very recent strains. We found that a participant's age at the time a strain first circulated was very predictive of the strength of their antibody against that strain. Not just for the first strain they were likely to have seen, but also for the second, third and all subsequent strains circulating during their lifetime. This suggests to us that antibody titers to influenza A H3N2 follow a pattern of antigenic seniority, suggesting that we produce progressively fewer specific antibodies to each subsequent infection as we age.
Collapse
Affiliation(s)
- Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Steven Riley
- School of Public Health, Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modelling, Imperial College, London, United Kingdom
- * E-mail:
| | - Jonathan M. Read
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Shuying Wang
- Guangzhou No. 12 Hospital, Guangzhou, Guangdong, China
| | - Huachen Zhu
- International Institute of Infection and Immunity, Shantou University Medical College, Shantou, Guangdong, China
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR, China
| | - Gavin J. D. Smith
- Laboratory of Virus Evolution, Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Yi Guan
- International Institute of Infection and Immunity, Shantou University Medical College, Shantou, Guangdong, China
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR, China
| | | | - Derek A. T. Cummings
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| |
Collapse
|
13
|
Lessler J, Cummings DAT, Read JM, Wang S, Zhu H, Smith GJD, Guan Y, Jiang CQ, Riley S. Location-specific patterns of exposure to recent pre-pandemic strains of influenza A in southern China. Nat Commun 2011; 2:423. [PMID: 21829185 PMCID: PMC3757505 DOI: 10.1038/ncomms1432] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 07/12/2011] [Indexed: 12/03/2022] Open
Abstract
Variation in influenza incidence between locations is commonly observed on large spatial scales. It is unclear whether such variation occurs on smaller spatial scales and whether it is the result of heterogeneities in population demographics or more subtle differences in population structure and connectivity. Here we show significant differences in immunity to influenza A viruses among communities in China not explained by differences in population demographics. We randomly selected households from 5 randomly selected locations near Guangzhou, China to answer a questionnaire and provide a blood sample for serological testing against 5 recently circulating influenza viruses. We find a significant reduction in the frequency of detectable neutralization titers with increasing age, leveling off in older age groups. There are significant differences between locations in age, employment status, vaccination history, household size and housing conditions. However, after adjustment, significant variations in the frequency of detectable neutralization titers persists between locations. These results suggest there are characteristics of communities that drive influenza transmission dynamics apart from individual and household level risk factors, and that such factors have effects independent of strain.
Collapse
Affiliation(s)
- Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public, Health, Baltimore, Maryland 21205, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Friedewald WF. QUALITATIVE DIFFERENCES IN THE ANTIGENIC COMPOSITION OF INFLUENZA A VIRUS STRAINS. ACTA ACUST UNITED AC 2010; 79:633-47. [PMID: 19871392 PMCID: PMC2135378 DOI: 10.1084/jem.79.6.633] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A study of the PR8, Christie, Talmey, W.S., and swine strains of influenza A virus by means of antibody absorption tests revealed the following findings: 1. Serum antibody could be specifically absorbed with allantoic fluid containing influenza virus or, more effectively, with concentrated suspensions of virus obtained from allantoic fluid by high-speed centrifugation or by the red cell adsorption and elution technique. Normal allantoic fluid, or the centrifugalized sediment therefrom, failed to absorb antibodies. Influenza B virus (Lee) caused no detectable absorption of antibody from antisera directed against influenza A virus strains, but it specifically absorbed antibody from Lee antisera. 2. The neutralizing, agglutination-inhibiting, and complement-fixing anti-bodies in ferret antisera were completely absorbed only by the homologous virus strain, even though 2 absorptions were carried out with large amounts of heterologous virus strains. 3. PR8 virus appeared to have the broadest range of specific antigenic components for it completely absorbed the heterologous antibodies in Christie and W.S. antisera and left only those antibodies which reacted with the respective homologous strains. The other virus strains (Christie, Talmey, W.S., swine) were more specific in the absorption of heterologous antibodies and completely removed only those antibodies which reacted with the absorbing virus. 4. The absorption tests revealed a higher degree of specificity and individuality of the virus strains than the various cross reactions previously reported. The strain specificity of PR8 virus was equally manifest in absorption tests with ferret sera and with human sera following vaccination. 5. The amount of homologous antibody remaining in a PR8 ferret serum after absorption with PR8 virus, obtained by the red cell adsorption and elution method, varied inversely as the concentration of virus used for absorption. A given concentration of virus, however, absorbed a greater percentage of neutralizing antibodies than either agglutination-inhibiting or complement-fixing antibodies.
Collapse
Affiliation(s)
- W F Friedewald
- Laboratories of the International Health Division of The Rockefeller Foundation, New York
| |
Collapse
|
15
|
Friedewald WF. THE IMMUNOLOGICAL RESPONSE TO INFLUENZA VIRUS INFECTION AS MEASURED BY THE COMPLEMENT FIXATION TEST : RELATION OF THE COMPLEMENT-FIXING ANTIGEN TO THE VIRUS PARTICLE. ACTA ACUST UNITED AC 2010; 78:347-66. [PMID: 19871335 PMCID: PMC2135412 DOI: 10.1084/jem.78.5.347] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A quantitative complement fixation test with influenza immune sera and virus antigens obtained from allantoic fluid is described. The method utilizes a photoelectric densitometer which provides a simple, objective, and accurate determination of the hemolytic reaction. The enhancement of the hemolytic activity of complement in the presence of serum or allantoic fluid necessitates a preliminary titration of complement in the presence of these agents. An accurate appraisal of the activity of the complement under the conditions of the actual test permits the selection of an optimal amount of complement and greatly increases the sensitivity of the test. The substance (or substances) responsible for the enhanced hemolytic activity of complement has been found in human and many animal sera and in allantoic fluids obtained from the developing chick embryo. It requires the presence of both complement and hemolysin, resists heating at 100°C. for 2 hours, and is dialyzable. Allantoic fluid or mouse lung preparations of influenza virus contain a complement-fixing antigen which is intimately associated with the virus particle. It sediments in the high speed centrifuge at the same rate as the hemagglutinin and infective particle and, like the latter, is adsorbed by fowl red blood cells and eluted from the cells on standing at room temperature or 37°C. It cannot be separated from the virus particle by repeated washings in the centrifuge or repeated adsorptions with red blood cells; the hemagglutinin and complement-fixing antigen titers remain roughly proportional. This antigen shows a high degree of strain specificity in cross complement fixation tests with PR8, W.S., and swine ferret antisera, and, as found with the neutralization test, it shows little or no strain specificity with human sera. A soluble antigen is also present in influenza virus preparations which can be readily separated from the virus particle by centrifugation. It is not adsorbed by red blood cells. Furthermore, it reacts in lower titer with ferret antisera and usually shows less strain specificity in cross complement fixation tests. In general, allantoic fluid virus preparations contain much less of the soluble antigen than mouse lung extracts.
Collapse
Affiliation(s)
- W F Friedewald
- Laboratories of the International Health Division of The Rockefeller Foundation, New York
| |
Collapse
|
16
|
FRANCIS T. Vaccination against influenza. Bull World Health Organ 1953; 8:725-41. [PMID: 13094502 PMCID: PMC2554195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023] Open
Abstract
This paper reviews studies which have been carried out during the past twenty years in the United States of America to investigate the suitability of various vaccines and vaccination methods for immunizing man against the different influenza virus strains. A number of investigations in closed communities, such as children's institutions, army and navy units, and medical schools, are described. The author discusses the comparative value of the techniques employed in preparing vaccines, and the use of adjuvants in improving the response.
Collapse
|
17
|
Antibody response against strains of influenza-A virus in ferrets with basic immunity. Antonie van Leeuwenhoek 1949. [DOI: 10.1007/bf02062642] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
18
|
Hirst GK. Vaccination against epidemic influenza. Med Microbiol Immunol 1949. [DOI: 10.1007/bf02184185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
19
|
|
20
|
Burnet FM, Beveridge WIB, Bull DR, Clark E. INVESTIGATIONS OF AN INFLUENZA EPIDEMIC IN MILITARY CAMPS IN VICTORIA, MAY, 1942. Med J Aust 1942. [DOI: 10.5694/j.1326-5377.1942.tb90400.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- F. M. Burnet
- Walter and Eliza Hall Institute of Research in Pathology and MedicineMelbourne
| | - W. I. B. Beveridge
- Walter and Eliza Hall Institute of Research in Pathology and MedicineMelbourne
| | - Diana R. Bull
- Walter and Eliza Hall Institute of Research in Pathology and MedicineMelbourne
| | - Ellen Clark
- Walter and Eliza Hall Institute of Research in Pathology and MedicineMelbourne
| |
Collapse
|