Immunogenicity testing of a recombinant N1 vaccine candidate, N1-MPP, adjuvanted with CpG 1018

Naive, female 6-8 week old BALB/c mice were either vaccinated once with 3 ug of recombinant N1-MPP, 3 ug N1-MPP + 3ug CpG 1018, or 3 ug of an irrelevant protein, or twice with the same formulations after a three week interval. Three weeks post boost, mice were challenged with 10x LD50 of A/Singapore/GP1908/2015 (H1N1) virus, and weight loss and survival were monitored over 2 weeks. Afterward, serological analysis was conducted and transferred to naive mice who were then challenged with 5xmLD50 of 140 A/Singapore/GP1908/2015 H1N1 to assess immunity. To determine whether CpG 1018 improves NA immunogenicity, even in admixtures to QIV, another prime boost regiment was conducted, in QIV admixtures, and mice were challenged once more.