Prospectus: Looking beyond typical correlates of influenza immunity.


Kelsey Florek
Prospectus
01 May 2017


Slides available at:
www.k-florek.net/talks

why now and the plan ahead

US percentage of all deaths due to pneumonia and influenza each week

CDC

influenza is a leading cause of death in the US (2014)

All causes of death 2,626,418 %
1 Diseases of the heart 614,348 23.4
2 Malignant neoplasms 591,700 22.5
3 Chronic lower respiratory diseases 147,101 5.6
4 Accidents (unintentional injuries) 135,928 5.2
5 Cerebrovascular diseases 133,103 5.1
6 Alzheimer's disease 93,541 3.6
7 Diabetes mellitus 76,488 2.9
8 Influenza and pneumonia 55,227 2.1
9 Nephritis, nephrotic syndrome 48,146 1.8
10 Intentional self-harm (suicide) 42,826 1.6
CDC

vaccine effectiveness varies each season

seasonal vaccine production cycle

global surveillance of influenza viruses

generation of ferret anti-sera

hemagglutination inhibition

hemagglutination inhibition

hemagglutination inhibition

influenza vaccination strains generated through reassortment

influenza vaccine selection is deeply flawed

  • vaccine only uses HA and NA from target strain
  • antigenic relatedness is determined using ferrets
  • potential protection evaluated using a method that indirectly determines neutralization
  • vaccine viruses manufactured in eggs

what other correlates of immunity could be used to improve vaccine effectiveness

outline of chapters

  1. heterosubtypic MVA vaccine and broadly reactive ADCC antibodies
  2. a mosaic antigen to elicit ADCC antibodies
  3. effects of seasonal influenza vaccination modality on ADCC antibodies
  4. capacity of a forward antigenic vaccine to generate broad antibody responses

part 1 - investigating pre-clinical vaccines

antibody dependent cell-mediated cytotoxcity (ADCC)

hypothesis: combination of NP and/or H5 in the MVA vector will elicit protective, cross-reactive T cell responses

heterosubtypic MVA vaccine and broadly reactive ADCC antibodies

summary

  • MVA vaccines stimulated strong neutralizing antibodies that afforded protection against a homologous challenge strain
  • vaccination with MVA-HA5-NP elicited binding but non-neutralizing antibodies against the heterologous H1N1 challenge strain
  • these binding but non-neutralizing antibodies were able to activate and trigger degranulation in natural killer cells, indicating ADCC could be an important measure of protection

status of work:

published in The Journal of Virology

hypothesis: a mosaic H5 delivered via an MVA vector will elicit broadly protective ADCC antibodies

a mosaic antigen to elicit ADCC antibodies

summary

  • mosaic MVA elicited binding and non-neutralizing antibodies capable of stimulating ADCC
  • viral loads appear correlated with ADCC antibody titer (more evidence is needed)
  • DNA or MVA prime had no noticeable effect

status of work:

addressing reviewer comments for resubmission to PLOS One

part 2 - investigating FDA approved vaccines

hypothesis: vaccination with the inactivated influenza vaccine will stimulate ADCC antibodies

effects of seasonal influenza vaccination modality on ADCC antibodies

  • 130 subjects
  • ages 5 - 17
  • serum collection
    • day of vaccination
    • 28 days post-vaccination
  • examined ADCC responses against:
    • A/Texas/50/2012
    • A/Switzerland/9715293/2013

summary

  • ADCC antibodies were present at baseline before exposure with A/Switzerland/9715293/2013
  • vaccination with LAIV followed by IIV during the next season had the greatest effect on ADCC antibodies

status of work:

manuscript in preparation for submission to PLOS One

hypothesis: vaccination with the A/Switzerland/9715293/2013 strain will boost antibody responses to historical strains

antigenic cartography

antibody landscape

antibody landscape over time

vaccines boost responses against previously circulating strains

using a unique situation to further investigate influenza back-boost

antigenic distance from A/Victoria/361/2011

capacity of a forward antigenic vaccine to generate broad antibody responses


  • cohort study
  • children aged 5-17 years
  • subjects recruited on previous exposure
    • 2014-15 IIV and uninfected n ~ 80
    • 2014-15 flu A infected n ~ 20
    • 2010-15 unvaccinated and uninfected n ~ 80
  • 2014-15 vax: A/Texas/50/2012
  • 2014-15 circ: A/Switzerland/9715293/2013

capacity of a forward antigenic vaccine to generate broad antibody responses


  • tested 4 viruses
    • A/Switzerland/9715293/2013
    • A/Texas/50/2012
    • A/Victoria/361/2011
    • A/Wuhan/359/1995
  • 2014-15 vaccination status
    • unvaccinated: 34 (27%)
    • vaccinated IIV: 77 (62%)
    • vaccinated LAIV: 13 (11%)
  • PCR confirmed influenza
    • 2012-13: 10 (8%) A/Texas/50/2012-like
    • 2014-15: 22 (18%) A/Switzerland/9715293/2013

using regression to model and predict qualitative and quantitative variables


  • examines the relationship between the response (dependent) variable and predictor (independent) variables
  • linear regression: quantitative response
  • logistic regression: qualitative response
  • predict responses while adjusting for confounding factors

how multiple regression works


how multiple regression works


linear regression analysis


  • response: post-vaccination HI titer
  • predictors:
    • mean fold increase against A/Switzerland/9715293/2013
    • baseline HI titer
    • age
    • high-risk condition
    • vaccination status
    • PCR confirmed infection status

logistic regression analysis


  • response: post-vaccination seroprotection
  • predictors:
    • mean fold increase against A/Switzerland/9715293/2013
    • baseline HI titer
    • age
    • high-risk condition
    • vaccination status
    • PCR confirmed infection status

vaccination increases the number of seroprotected subjects against the previous season strain


  • A/Texas/50/2012 HI titer ≥ 1:40
    • 29 subjects had baseline HI titer < 1:40
    • 15 (52%) of those subjects had a post-vaccination HI titer ≥ 1:40
  • A/Texas/50/2012 HI titer ≥ 1:110
    • 114 subjects had baseline HI titer < 1:110
    • 12 (11%) of those subjects had a post-vaccination HI titer ≥ 1:110

vaccination increases the number of seroprotected subjects against the previous season strain


  • (A/Texas/50/2012 HI titer ≥ 1:40) 2-fold increase in HI titer against A/Switzerland/9715293/2013
    • 5.9 times higher odds of seroprotection
    • 95% CI 2.0 - 44.1
    • P = 0.01
  • (A/Texas/50/2012 HI titer ≥ 1:110) 2-fold increase in HI titer against A/Switzerland/9715293/2013
    • 2.1 times higher odds of seroprotection
    • 95% CI 1.4 - 3.4
    • P = 0.0008

summary


  • seasonal influenza vaccination provides a small but real boost to antibodies against historical antigens
  • few participants were boosted to an HI titer ≥ 1:110 against A/Texas/50/2012 suggesting the historical boost may not be clinically significant for children

status of work:

at CDC for submission clearance to The Journal of Infectious Diseases

drawbacks of influenza vaccines

  • current vaccines are limited in breadth
  • low vaccine effectiveness
  • repeated annual vaccination

implications


  • ADCC has potential for stimulating broadly protective responses
    • seasonal vs pandemic vaccines and approaches to vaccination
    • effects of repeated exposure on ADCC responses
  • value of the back-boost response
    • expansion of strain specific B cells vs cross-reactive antibodies
    • selecting forward antigenic strains
    • antigen trapping

acknowledgements

  • Friedrich Lab
    • James Mutschler
    • Luiza Campos
    • Kat Braun
    • Louise Moncla
  • Marshfield Clinic Research Foundation
    • Edward Belongia
    • Huong McLean
    • Jennifer King
  • Centers for Disease Control and Prevention
    • Brendan Flannery
funding provided by:
  • SciMed Graduate Research Scholars

  • Molecular Biosciences Training Grant