Research led by Oxford University team, on mice has shown that a type of polymer called polyethyleneimine (PEI) is a potent adjuvant for test vaccines against these deadly viruses.
An adjuvant is added to a vaccine to boost immune response and offer better protection against infection.
Mice given a single dose of a flu vaccine laced with PEI via a nasal droplet were completely protected against a lethal dose of flu, a marked improvement over those given the shot without PEI or in formulations with other adjuvants, the journal Nature Biotechnology reported.
"Gaining complete protection against flu from just one immunisation is pretty unheard of, even in a study in mice," says Quentin Sattentau, professor of pathology at the Oxford's Dunn School of Pathology, who led the work, said in a Oxford statement.
"This gives us confidence that PEI has the potential to be a potent adjuvant for vaccines against viruses like flu or HIV, though there are many steps ahead if it is ever to be used in humans," adds Sattentau.
When included in a vaccine with a protein from HIV, flu or herpes virus, mice subsequently mounted a strong immune response against that virus.
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The immune response was stronger than with other adjuvants that are currently being investigated.
Oxford researchers now intend to test the PEI adjuvant in ferrets, a better animal model for studying flu. It is likely to be a couple of years before a flu vaccine with this adjuvant could be tested in clinical trials.
HIV, flu and herpes are some of the most difficult targets to develop vaccines against. HIV and flu viruses are able to change and evolve to escape immune responses stimulated by vaccines.
There aren't any effective vaccines against HIV and herpes as yet, and the flu vaccine needs reformulating each year and doesn't offer complete protection to everyone who receives it.
Finding better adjuvants could help in developing more effective shots against these diseases.