Self-amplifying mRNA seasonal influenza vaccines elicit mouse neutralizing antibody and cell-mediated immunity and protect ferrets.

Currently licensed influenza vaccines focus immune responses on viral hemagglutinin (HA), while the other major surface glycoprotein neuraminidase (NA) is not tightly controlled in inactivated vaccine formulations despite evidence that anti-NA antibodies reduce clinical disease. We utilized a bicistronic self-amplifying mRNA (sa-mRNA) platform encoding both HA and NA from four seasonal influenza strains, creating a quadrivalent influenza vaccine. sa-mRNA vaccines encoding an NA component induced the production of NA-inhibiting antibodies and CD4+ T-cell responses in both monovalent and quadrivalent formulations. Including NA in the vaccine enabled cross-neutralization against antigenically drifted strains and provided greater protection than HA alone upon A(H3N2) challenge in ferrets. These results demonstrate that next-generation bicistronic sa-mRNA vaccines expressing HA and NA induce potent antibodies against both viral coat proteins, as well as vaccine-specific cell-mediated immunity. When formulated as a quadrivalent seasonal influenza vaccine, the sa-mRNA platform provides an opportunity to increase the breadth of protection through cross-neutralizing anti-NA antibodies.

Francisella tularensis Infection of Mice as a Model of Sepsis.

Sepsis results from the dysregulated immune response to infection. While the stimulator and progression of the septic response is poorly understood, the systemic production of a storm of cytokines is common in all etiologies of sepsis. While the complexity of this uncontrolled cascade is difficult to replicate using single molecule agonist, for example, lipopolysaccharide (LPS), several whole organism models can stimulate this cytokine storm. Herein, we detail protocols developed to trigger and analyze the systemic septic response in mouse models using the bacterium Francisella tularensis.