Figure 2.

Comparison of MC3, KC2, and L319 LNPs in mice and NHPs with unmodified and 1MpU-modified mRNA

(A) Individual and mean HI titers measured in sera collected from Balb/c mice (n = 8/group) after a single immunization (D20) and two immunizations (D42) with 5 μg of a monovalent A/California/07/2009 (H1N1) split influenza vaccine (Vaxigrip; MIV) or with 5 μg of unmodified mRNA (UNR) or 1MpU-modified mRNA (MNR) encoding full-length hemagglutinin (HA) of closely related influenza virus strain A/Netherlands/602/2009 (H1N1). The mRNA was encapsulated into MC3 (green), KC2 (purple), or L319 (orange) LNPs. Immunization was performed by 2 i.m. injections into the quadriceps given 3 weeks apart (D0, D21) under a final volume of 50 μL of PBS. For each lipid, UNR versus MNR comparison was performed by ANOVA after log transformation of the HI titers. When difference was significant, p-value was reported directly on the graph (B) 500 μL fractions of the mRNA vaccines used for the immunization of mice (i.e., 50 μg of UNR or MNR) were used to immunize cynomolgus macaques. The macaques (n = 4/group) were immunized by 2 i.m. injections into the deltoid given 4 weeks apart (D0, D28). A control group received 15 μg of the monovalent A/California/07/2009 Vaxigrip (MIV) following the same schedule. Individual and mean HI titers measured after a single immunization (D28) and after two immunizations (D55 and D85) are shown. A given symbol was attributed to each individual macaque from the different groups and kept the same throughout the graphs. (C) 8 weeks following the second immunization (D85), PBMCs were collected from the macaques for the determination of antibody-secreting cells (ASCs). The percentage of antigen-specific ASCs to the total IgG + ASCs is shown for each individual macaque represented by its symbol. The bar represents the mean for the group.