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Combined use of live-attenuated and inactivated influenza vaccines to enhance heterosubtypic protection

Li-Meng Yan, MD, Ph.D

Centre of Influenza Research,

School of Public Health,

The University of Hong Kong

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BACKGROUND

Protection from commercial influenza vaccines is far from optimal when the vaccine strains antigenically do not match with the circulating viruses.

Currently licensed influenza vaccines have their limitations.

live attenuated influenza vaccine (LAIV), inactivated influenza vaccine (IIV), and recombinant influenza vaccine (RIV)

Novel vaccination approaches.

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Hierarchical clusters of HA subtypes

Ge, Hu, et al. Natural product reports (2010)

Aim of study

Subtype-specific influenza vaccines (Group 1 HA: H1 or H5)

Broadly cross protections

Level of cross protections

induced by different combinations of vaccination regimens.

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Highlights

Sequential vaccination can generate heterosubtypic protection against IAV.

Combined use of LAIV + IIV induces good cross protection.

Different vaccination regimens can induce different immune profiles.

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Wyeth/IL-15/5Flu (5Flu)

A novel vaccinia-based live-attenuated pentavalent vaccine
HA, NA and NP (H5N1/A/Vietnam/1203/2004)
M1 and M2 (H5N1/A/CK/Indonesia/PA/2003)
Adjuvant human IL-15

Previous studies revealed:
Trigger both MHC I and II antigen processing machineries
Elicit robust CD4 and CD8 T cell responses
Induce good cross-protection.

Publications:

Poon LL, et al. The Journal of Immunology. (2009)
Valkenburg SA, et al. PNAS. (2014)

5Flu might be a promising candidate to serve as a universal vaccine.

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4-dose sequential vaccination regimens

in Balb/c mouse model

8-week old Balb/c mice.

After sequential vaccination, either scarificed for No Challenge (NC)

Or challenged (i.n.) with a lethal dose of heterologous IAV.

* IIV:

sH1: Seasonal H1N1/Brisbane/07

pdmH1: Pandemic H1N1/California/09

H5: H5N1/Vietnam/04

AddaVax™: Adjuvant for inactive vaccines

Sequential immunization schedule*:

(-): PBS – PBS – PBS – PBS

V: PBS – PBS – 5Flu – 5Flu

inH1: sH1 – pdmH1 - PBS – PBS

inH1/V: sH1 – pdmH1 – 5Flu – 5Flu

inH1/H5: sH1 – pdmH1 – H5 –H5

Vaccination (i.m)

1^st

2^nd

3^rd

4^th

NC

or

(i.n)

3 weeks

3 dpi

7 dpi

14 dpi

Lung

Lung, BAL,

Spleen,

Serum

Weight loss, general observation & Survival rate

Yan, Li-Meng, et al. Virology 525 (2018): 73-82.

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HA	Survival (%)	(-)	V	inH1	inH1/V	inH1/H5
Group 1	H1N1	0	18	55	100	100
Group 2	H3N2	0	75	42	92	83
Group 2	H7N7	20	80	40	100	60

Sequential vaccinations generate strong cross-protection against infections caused by different subtypes

For heterosubtypic protection, LAIV is more potent than IIV.

Repeated immunization can lead to better protection.

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Viral loads in the lungs, at 3 and 7 dpi

Total protein concentration in BAL, at 7 dpi

Sequential vaccinations reduce severity of illness of infected mice

Group inH1/V mice had the least lung injury.

Group inH1/V: superior to IIV alone.

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Sequential vaccinations induce efficient cross-protective antibodies

Antigen	IgG1
Antigen	V	inH1	inH1/V	inH1/H5
Group 1 HA
sH1	80	2560	1280	2560
pdmH1	160	1280	2560	2560
Group 2 HA
H3N2/HK68	80	160	640	320

Antigen	IgG2α
Antigen	V	inH1	inH1/V	inH1/H5
Group 1 HA
sH1	<80	320	320	640
pdmH1	<80	<80	160	320
Group 2 HA
H3N2/HK68	<80	<80	<80	<80

Group inH1/V : IgG1.

Serum, No Challenge

IIV: IgG2α against Group 1 HA

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Sequential vaccinations induce efficient cross-protective antibodies

Influenza-NP specific IgG1 Ab profiles.

Serum, NC Vs at 7 dpi.

Group inH1/V: IgG1.

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In serum, with Geometric mean titers (GMT).

Sequential vaccinations induce efficient cross-neutralizing antibodies

NO pre-existing cross-nAbs induced by sequential vaccination regimens.

0.18	0.54	1.90	1.90

0.91	0.50	1.27	1.01

At 7 dpi

Group inH1/V: most potent regimen after infections.

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Influenza immunodominant NP or HA epitope-specific CD8 T-cell responses.
For Type-1 cytokines (IFN-γ, TNF-α, IL-2) and Type-2 (IL-4).

Sequential vaccinations improve influenza-specific T-cell responses

Group inH1/V: type 1 CKs against NP and HA, including mono-functional and poly-functional (IFN-γ+TNF-α+)

Group inH1/H5 : NP-specific responses.

No good IL-2 and IL-4.

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Influenza immunodominant NP or HA epitope-specific CD4 T-cell responses.
For Type-1 cytokines (IFN-γ, TNF-α, IL-2) and Type-2 (IL-4).

Sequential vaccinations improve influenza-specific T-cell responses

Group inH1/H5: TNF-α against NP and HA.

Group V: TNF-α against NP.

Different vaccine compositions induce different biases in T cell responses.

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In BAL, at 7 dpi.

Good Tc1 CKs were detected.

Group inH1/V: against HA after H1N1 or H3N2.

Groups inH1 and inH1/H5: NP-induced responses after a H1N1, but not H3N2.

Sequential vaccinations exert effectively localized recall of CD8 T cell responses against heterologous IAV

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Sequential vaccinations exert effectively systemic recall of CD8 T cell responses against heterologous IAV

In spleen, at 7 dpi.

Good Tc1 CKs were detected.

Group inH1/V: against HA after H1N1 or H3N2.

Groups V: NP-induced responses after a H1N1, but not H3N2.

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Summary

All studied 4-dose vaccinations could induce some degrees of heterosubtypic protection in mice.

Combined use of LAIV + IIV vaccines could achieve the best heterologous protection.

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Conclusion

Potential benefits of combined use of LAIV + IIV vaccines.

Best protection against lethal challenge of heterologous IAV in mice.

Developing alternative vaccine strategies for universal protection.

Relevant immunologic information.

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Acknowledgement

Funding

Health and Medical Research Fund of Hong Kong (HMRF14130962)

National Institutes of Health

(NIAID contract HHSN272201400006C)

Research Grant Council of Hong Kong

(Project No. T11-705/14N).

Prof. Leo LM POON’s Lab

Prof. Leo LM POON

Prof. Malik PEIRIS

Dr. Olive TW LI

Dr. CM POH

Dr. Ranawaka A.P.M. PERERA

Dr. Sophie A. VALKENBURGA

…AND our labmates