Document Type

Data

Publication Date

3-10-2026

Abstract

Current vaccine formulations heavily rely on cold chains to avoid
degradation during transportation and storage. Vaccines typically degrade
when exposure to temperature outside of 2 – 8°C range, leading to waste and
logistical challenges, particularly in rural areas. This study investigates
the ability of poly(lysine)- and poly(glutamate)-based peptide coacervates
to improve the thermal stability of porcine parvovirus (PPV), a model
non-enveloped viral vaccine. We hypothesized that both the length and
specific amino acid sequence of the peptides forming the coacervates would
influence the stability of PPV. Long polypeptides (400–800 mers) provided
significant protection, slowing PPV inactivation at 60°C for up to seven
days by as much as 4 logs (10,000-fold), whereas shorter 48-mers offered
limited stability. Modifying peptide sequences revealed that glutamate
block copolypeptides at larger block sizes improved thermostability, while
incorporating alanine residues into lysine block copolypeptides improved
stabilization beyond that achieved by with long homopolypeptides. The
addition of sucrose in the formulations further improved thermostability,
while trehalose showed minimal benefit. While coacervation did not have a
significant impact on viral infectivity, [SP2.1]in vivo studies
demonstrated that coacervated PPV yielded lower antibody responses compared
to native virus, indicating the presence of polypeptide–capsid interactions
specific to immunogenic epitopes. Overall, this study showed that
coacervate formulations can be adjusted to enhance virus thermal stability;
however, further work is necessary to understand how such formulations can
provide thermostability without altering the immune response necessary for
a successful vaccine. Such design principles would enable the development
of formulations that could decrease the vaccine cold-chain dependence and
improve vaccine accessibility.

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