Fig. 3.

Interprotomer disulfide-stabilized HMPV F variants induce high titer-neutralizing responses in mice. (A) Immunization regimen for CB6F1J mice (n = 10/group) with two HMPV F immunizations followed by serum analysis at week 5. (B) Elicited HMPV neutralization by prefusion F immunogens; experiment was carried out in two sets of mice, one set with v1-B and v3-B and a second set with v2-B. (C) Elicited HMPV neutralization by postfusion F immunogens; immunization experiment was carried out in a single set of mice. v4-B is significantly more immunogenic than postfusion F (P value = 0.0009 based on Mann–Whitney test; even if the highest response is removed, it would still be statistically better, with a P value = 0.002 based on a Mann–Whitney test). (D) Comparison of titers elicited by IP-DS–stabilized prefusion and postfusion forms of HMPV F.