Download 5:15 p.m. 244. Combination Nanovaccine provides protection

Combination nanovaccine provides protection against influenza in aged mice
Ross Darling1, Kathleen Ross2, Sujata Senapati2, Jessica Alley3, Matthew Jefferson4, Michael J. Wannemuehler1, Surya
Mallapragada2, Marian Kohut3, Balaji Narasimhan3
1
Veterinary Microbiology and Preventive Medicine; 2Chemical & Biological Engineering; 3Kinesiology; and 4Neuroscience.
Iowa State University, Ames, IA
Statement of Purpose: Influenza is responsible for a
significant number of hospitalizations and mortalities in
individuals of all age groups. However, the heaviest
burden of influenza resides in the elderly, the fastest
growing segment of the U.S. population. Despite
increased vaccination programs, the effectiveness of
influenza vaccines in the elderly is highly variable due to
age-associated deficiencies of the immune response [1, 2].
Thus, next generation vaccines that may overcome age
related immune deficiencies are needed urgently.
Polyanhydride nanoparticles represent an adjuvant
platform that provides sustained release of encapsulated
antigen, leading to enhanced humoral and cell-mediated
immune responses [3, 4]. In addition, novel pentablock
copolymer-based micelles promote rapid antibody
development, and in combination with polyanhydride
nanoparticles and/or other adjuvants, may activate
multiple immune activation pathways [5]. In this work,
we demonstrate that a combination nanovaccine
formulation can improve immune efficacy in aged mice
subsequently infected with influenza A virus compared to
existing inactivated virus vaccines.
Methods: Dendritic cells (DCs) derived from bone
marrow and spleens of young (6-7 weeks) and aged (18
months) mice were cultured and stimulated in vitro with
polyanhydride nanoparticles, micelles, imiquimod (TLR7
agonist) and cyclic dinucleotides (STING pathway
activator). The expression of cell surface markers was
examined via flow cytometry. In addition, cytokine
secretion was measured via a multiplex assay.
To assess the protection provided by the
nanovaccines against H1N1 virus challenge, aged and
young mice were subcutaneously immunized with 20 µg
H1 hemagglutinin and 20 µg nucleoprotein in a primeboost or single dose regimen. Total anti-HA and anti-NP
IgG serum antibody titers were determined at 21 days and
32 days post-immunization via ELISA. Additionally,
serum hemagglutination-inhibition titers were also
examined. Finally, body weight and survival was
monitored for two weeks post challenge with 1 LD50 IAV.
Results: Following the stimulation with nanoadjuvants,
the expression of cell surface markers such as CD40,
CD80, and CD86 was enhanced in bone marrow dendritic
cells (BMDCs) of both age groups (Figure 1). In
particular, DCs stimulated with nanoparticles or micelles
had the greatest upregulation of co-stimulatory markers.
Upon immunization with the combination
nanovaccine, robust anti-HA and anti-NP antibody titers
were generated in young mice while aged mice
administered the nanovaccine had lower titers in
comparison. These titers were greater than mice
administered an inactivated virus (IAV) control.
Clinically, the nanovaccine protected the aged mice as
evidenced by the mild weight loss in these IAV infected
mice relative to control (i.e., saline treated) mice (Figure
2).
Figure 1. Nanovaccine adjuvants enhance surface expression of
BMDCs.
Figure 2. Nanovaccines protected aged mice from weight loss postchallenge.
Conclusions: In this work, multiple adjuvants were
demonstrated to enhance expression of co-stimulatory
molecules and cytokine secretion from both aged and
young mice. While the antibody titers in aged mice were
lower in comparison to young mice, these titers were
greater than control animals immunized with an
inactivated virus vaccine. Furthermore, mice immunized
with the nanovaccines formulation demonstrated less
weight loss post-challenge. Together, these data
demonstrate the potential of nanovaccines to overcome
age-related immune defects and enhance vaccine efficacy.
References:
[1] McElhaney JE. Ageing Res. Rev. 2011; 10: 379-88.
[2] Haynes L, Swain SL. Immunity 2006; 24: 663-6.
[3] Ross KA, et al. Int. J. Nanomedicine 2015; 10: 229-43.
[4] Ross KA, et al. J. Biomed. Mater. Res. A. 2014; 102: 41618.
[5] Ross KA, et al. ACS Biomater. Sci. Eng. 2016; 2: 368-374.