Advax®-adjuvanted inactivated influenza vaccine provides accelerated protection of mice via early induction of an influenza-specific IgM response.

It would be advantageous if a strategy could be found to accelerate vaccine induction of anti-influenza adaptive immunity to more rapidly protect frontline workers and other vulnerable individuals during virus outbreaks. This study asked whether Advax® delta inulin adjuvant could accelerate the kinetics of protection afforded by a single dose of inactivated influenza vaccine (IIV) in two different strains of mice. A single dose of Advax®-adjuvanted IIV, but not IIV alone, gave complete protection if given 7 or 3 days before, and even when given at the same time as virus challenge (same day protection). Co-administration of both IIV and Advax® were critical to obtaining robust same day protection which was not seen with the individual vaccine components. Same day protection was lost in B-cell deficient μMT mice but was still evident in T cell-depleted mice, confirming its dependence on humoral but not T cell immunity. Day 6 post-challenge serum from protected mice demonstrated elevated influenza-binding IgM which had hemagglutination inhibition activity not seen in mice that received IIV alone. This confirmed that Advax® accelerated the kinetics of anti-influenza IgM production in response to IIV. Influenza protection could be transferred to naïve mice using day 6 sera or purified IgM from Advax®-adjuvanted IIV-immunised mice. Draining lymph nodes from protected mice showed increased CD138