Flu Vaccine: Nasal Drops May Succeed Where Shots Have Failed

Flu viruses adapt and mutate, making influenza vaccines less effective. New research – published in the journal Science – has found a way to break down the virus’s defenses, giving future flu vaccines a boost.

Researchers from the University of California, Los Angeles – led by Ren Sun, a professor of molecular and medical pharmacology working in the university’s David Geffen School of Medicine – came up with a wholly new approach to developing flu vaccines.

Conventional vaccines reduce “immunogenicity” – that is, the ability of a substance to trigger the body’s immune response – by attenuating the virus. But the new approach preserves robust immune responses and works by identifying and eliminating the so-called immune evasion function of the viruses.

The body’s “first-line defense” function is for interferons to neutralize viruses as quickly as possible, while the “second line” of defense is to modulate our immune response, thereby offering us long-term protection against viruses. Interferons are signaling proteins that coordinate our immune response. As Sun explains, “If viruses do not induce interferons, they will not be killed in the first-line defense; and without interferons, the adaptive immune response is limited. “For these reasons, viruses have evolved strategies to evade detection and limit the production of the interferons by host organisms,” he added.

So, Sun and team found and disabled a genomic sequence of the influenza virus responsible for the interferon induction. “By disabling these interferon-evasion function,” explains first study author Yushen Du, “the engineered virus is weakened in typical hosts.” “At the same time,” she adds, “due to interferon stimulation, the engineered virus generates very strong immune responses.”