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

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

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:

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:

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:

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

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:

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

funding provided by:

• SciMed Graduate Research Scholars

• Molecular Biosciences Training Grant