A novel vaccine adjuvant for recombinant flu antigens

Many new vaccines under development consist of rationally designed recombinant proteins that are relatively poor immunogens unless combined with potent adjuvants. There is only one adjuvant in common use in the U.S., aluminum phosphate or hydroxide (e.g. alum). This adjuvant, however, has significant limitations, particularly regarding the generation of strong cell-mediated (T-cell) immune responses. A novel adjuvant, JVRS-100, composed of cationic liposome–DNA complexes (CLDC) has been evaluated for immune enhancing activity. The JVRS-100 adjuvant has been shown to elicit robust immune responses compared to CpG oligonucleotides, alum, and MPL adjuvants, and efficiently enhances both humoral and cellular immune responses. Safety has been evaluated in preclinical studies, and the adjuvant is now in early-stage clinical development. One application of this novel adjuvant is to augment the immune responses to recombinant subunit antigens, which are often poorly immunogenic. The JVRS-100 adjuvant, when combined with a recombinant influenza hemagglutinin (H1), elicited increased specific antibody and T-cell responses in mice. Single-dose vaccination and prime/boost vaccinations with JVRS-100-H1 were both shown to be protective (i.e., survival, reduced weight loss) following H1N1 (PR/8/34) virus challenge. Enhanced immunological responses could be critically important for improved efficacy and dose-sparing of a recombinant influenza vaccine.