Studying Repeated Immunization in an Animal Model. Kanta Subbarao Laboratory of Infectious Diseases, NIAID

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1 Studying Repeated Immunization in an Animal Model Kanta Subbarao Laboratory of Infectious Diseases, NIAID

2 Animal models in Influenza Research Commonly used Mice Ferrets Guinea pigs Non human primates Less commonly used Pigs Hamsters

3 Priming with Seasonal Influenza Virus Vaccines or Infection for Responses to the 2009 Pandemic H1N1 Vaccine

4 Experimental Approach Dose 1 Dose 2 s TIV s LAIV 2009 ph1n1 ca vaccine sh1n1 wt 2009 ph1n1 ca vaccine Serum for Ab Lung CTLs Challenge with 2009 ph1n1 wt Quantitative virology in lungs and nasal turbinates Chen, Lau, PNAS 2011

5 Live virus vaccine & infection elicits cross-reactive ELISA Ab responses to the 2009 ph1n1 virus ph1n1 Chen, Lau, PNAS 2011

6 Seasonal influenza virus vaccines do not prime for neutralizing Ab responses to the 2009 ph1n1 virus ph1n1 Chen, Lau, PNAS 2011

7 Seasonal LAIV and wt virus prime for a brisk CD8 recall response by the 2009 ph1n1 ca virus Chen, Lau, PNAS 2011 Chen, Lau, PNAS 2011

8 Seasonal LAIV and wt virus prime for a brisk CD8 recall response by the 2009 ph1n1 ca virus Chen, Lau, PNAS 2011

9 Seasonal LAIV and wt virus prime for a brisk CD8 recall response by the 2009 ph1n1 ca virus Chen, Lau, PNAS 2011

10 Seasonal LAIV and wt virus prime for a robust CD4 response to the 2009 ph1n1 ca virus IFNγ secreting CD4 cells were enumerated 5 days following 2 infection; APCs: naïve splenocytes pulsed with ph1n1 virus Chen, Lau, PNAS 2011

11 Summary Dose 1 Dose 2 Ab against ph1n1 Flu specific Pulmonary T cell Protection ELISA Nt CD8 CD4 URT LRT - plaiv + - +/

12 Summary Dose 1 Dose 2 Ab against ph1n1 Flu specific Pulmonary T cell Protection ELISA Nt CD8 CD4 URT LRT - plaiv + - +/ stiv plaiv + - +/

13 Summary Dose 1 Dose 2 Ab against ph1n1 Flu specific Pulmonary T cell Protection ELISA Nt CD8 CD4 URT LRT - plaiv + - +/ stiv plaiv + - +/ slaiv plaiv / sh1n1 plaiv /

14 Summary Dose 1 Dose 2 Ab against ph1n1 Flu specific Pulmonary T cell Protection ELISA Nt CD8 CD4 URT LRT - plaiv + - +/ stiv plaiv + - +/ slaiv plaiv / sh1n1 plaiv / plaiv plaiv /

15 Assessment of Vaccine Efficacy in Ferrets Type of challenge: Stringent Intranasal (widely used) vs. intratracheal (in some institutions) High dose of challenge virus (~10 5 ID 50 or a lethal dose if known) Homologous and heterologous challenge viruses Outcome measures: Clinical signs and symptoms Viral replication Nasal washes at serial time points: Avoids sacrificing animals for tissue sampling but does not provide information on replication in the lower respiratory tract or extrapulmonary sites Sacrifice animals at serial time points and sample upper and lower respiratory tract; should be done at 2 time points to assess peak and kinetics of viral replication and clearance

16 Measured in Ferret Studies Clinical signs: body temperature, weight, activity Virologic: nasal wash titer and duration of shedding Serologic: antibody titers, cellular immunity Ability to influence efficiency of transmission to direct contact or airborne contact ferrets

17 Effects of priming (contd) Prior infection with seasonal H1N1 (but not seasonal TIV) altered morbidity from ph1n1 in ferrets despite the detection of minimal levels of cross reactive Ab. Transmission to contact ferrets was not affected. Ellebedy CVI 2010, Vaccine 2011 MF-59 adjuvanted seasonal TIV does not induce crossreactive Ab or protection against ph1n1 infection in ferrets but primes well for a single dose of ph1n1 vaccine; basis: cross-reactive CD4+ T cell help or cross-reactive memory B cells. Del Giudice STM 2009 Priming with DNA vaccine boosts immunogenicity of H5N1 LAIV in ferrets. Suguitan PLoS One 2011

18 Multiple doses of seasonal (s) H1N1 induce cross-protective immunity against H1N1pdm09 Ferret model: 2 doses of stiv+ifa High levels of Ab and protection against homologous challenge but no Xreactive HAI or MN Ab vs H1N1pdm09 Preinfection induces sterilizing immunity vs homologous challenge and reduced replication, milder infection on heterosubtypic challenge; 2 preinf>1. Multiple pre-infection (2 sh3 or 2s H1 or sh3 and sh1) leads to infection rate, duration of shedding and transmission following H1N1pdm09 No adverse events Laurie et al JID 2010

19 Priming with plaiv followed by ISV boost elicits a robust antibody response in humans plaiv Vaccine # doses H5N1 VN04 ISV/do se 2 H5N1 VN04 45μg H7N7 2 H7N7 45μg Interval (months) HAI titer 14 days following ISV n GMT (range) Responders % GMT (5-1280) (2-1024) Talaat et al. J Infect Dis 2014; 209(12): ; Babu et al. Vaccine 2014; 32(50):

20 Repeated vaccination studies in animal models Issues to Consider: Interval between vaccine doses Homotypic immunity is very robust in animal models Heterosubtypic immunity in mice and ferrets is more robust than in humans Valency of the vaccines administered Nature of the vaccines: recombinant HA? Inactivated subunit? Whole inactivated? Live attenuated? Interpretation of results

21 Repeated Immunization with Vaccine (V) followed by Challenge Infection (Inf) V V V Inf Which species? Ferrets? Mice? Non human primates? Which outcomes would meaningfully capture VE outcomes Clinical signs? Viral replication? Is viral titer in the upper respiratory tract sufficient?

22 Possible scenarios - 1 Inf1 V2 V3 Inf1 V3 Inf1 Is repeated annual vaccination with the same strain worse for you than changing vaccine antigens each time? Compares the effect of 2 prior vaccinations on protection conferred by Vaccine 3 However, this design only evaluates protection against 1 strain of influenza: matched OR drift variant

23 Possible scenarios - 2 V2 V2 V3 V3 Inf1 Inf2 Compares the effect of 3 sequential vaccinations on protection against infection with a matched virus (Inf1) or a drift variant (Inf2) However, this design does not include control groups that were not vaccinated repeatedly.

24 Possible scenarios - 3 Compares the effect of 2 prior vaccinations on protection conferred by Vaccine 3 against infection with a matched virus (Inf1) or a drift variant Inf2 and includes a comparison Inf1 V2 V3 Inf1 V2 V3 Inf2 V3 Inf1 V3 Inf2 Inf1 Optional Inf2

25 Possible scenarios - 3 Compares the effect of 2 prior vaccinations on protection conferred by Vaccine 3 against infection with a matched virus (Inf1) or a drift variant Inf2 and includes comparisons Inf1 V2 V3 Inf1 V2 V3 Inf2 V3 Inf1 V3 Inf2 Inf1 Optional Inf2

26 Study Design Considerations Which species? Sample size is difficult with ferrets and NHPs Which vaccine(s)? LAIV or inactivated vaccine? Dose of inactivated vaccine: 15 micrograms? Adjuvant? What interval? Selection of challenge viruses Associated clinical illness? Viral replication in nasal wash samples? Viral replication in the lower respiratory tract? Is there evidence of vaccine related harm? Kobinger JID 2010; Sample size, study duration, investigation of late morbidity and mortality are critical.