Fig. 2: Polyclonal antibodies to PyTRAP inhibit parasite invasion, traversal, and in vivo infection.

Mice were immunized three times with PyTRAP or PyCSP ectodomains. a Immune sera were used to verify binding to Py sporozoites via immunofluorescence. Shown is a representative example of fixed, permeabilized sporozoites labeled with a 1:100 dilution of polyclonal mouse serum from PyTRAP immunization. The anti-mouse IgG (anti-TRAP serum) is in the red channel shown alone on the left and in combination with anti-CSP mAb 2F6 (green channel) and a DAPI nuclear stain (blue channel); 10-µm scale bars are shown. Immune sera were then assessed for function in vitro for inhibition of invasion (b) and traversal (c). In b and c, pooled serum from cohorts of n = 5 mice (number of cohorts indicated above each bar) was tested in three independent assays. Each data point represents the average “% of pre-immune” invasion or traversal of these independent assays for each cohort pool. Each bar indicates the group mean, with error bars representing the standard error of the mean. Values representing percent changes from 100% (indicated by dotted lines) are shown above. Asterisks indicate a significant difference from 100% as determined by a two-tailed one-sample t-test. d Immunized mice were challenged by the bite of 15 PyGFPluc-infected mosquitoes and assessed for parasite liver burden by bioluminescent imaging. Each data point represents an individual mouse with each color corresponding to an independent immunization-challenge experiment (total number of animals shown above each bar). Each data point was normalized to the mean flux from “naive” mice within each challenge experiment, while “control” mice were an additional group immunized with HIV Env gp120 protein. Each bar indicates the group mean, with error bars representing the standard error of the mean. Values representing percent changes from 100% (indicated by a dotted line) are shown above. Asterisks indicate significance as determined by ANOVA with Kruskal–Wallis post-test. For b–d, * is p ≤ 0.05; ** is p ≤ 0.01; and **** is p ≤ 0.0001.