Figure 2.

(A–D) DNA vaccination with tick salivary gland genes TSLPI, tHRF, Salp15, and Tix-5 in a 0-14-28 day immunization protocol. (A) Specific total IgG titers were measured in an Enzyme-linked immunosorbent assay (ELISA). Plates were coated with recombinant protein and incubated with mouse sera collected at timepoint 42 days pre-challenge. Sera was diluted in steps of 3 starting with 100 times and ending with 218,700 times dilution. Presented are the total IgG titers incubated with mouse sera 1:300 diluted for the tick salivary gland gene DNA vaccines. Statistical significance was calculated for each experimental group compared to the control, Empty pvax, using a one-way ANOVA statistical test (p< 0.05, **p<0.01, ***p<0.001, ****p<0.0001). (B) Borrelia loads in skin samples of the tick attachment site as determined by qPCR. Closed dots depict positive Borrelia loads, open dots depict PCR negative samples for which the OspA detection limit was divided by the sample’s mouse beta actin load. The Borrelia loads were compared to the negative control Empty pvax using a two-sided non parametric test (Mann-Whitney *P < 0.05, **P<0.01, ***P<0.001). (C) Tick weights in mg. Immunized mice were challenged with B. burgdorferi N40-infected I. scapularis nymphs. Nymphs were placed in a collection capsule on the back of each mice. The capsules were checked daily and the ticks were allowed to feed to repletion. Once they had fallen off their weight was measured. (D) Tick attachment is presented as percentage of ticks that are still attached per day. ns, not significant.