IL-21 signaling is dispensable for antibody recall responses to secondary RABV challenge.

<p>A) Five weeks post-immunization, mice immunized in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002129#pntd-0002129-g001" target="_blank">Figure 1</a> with 10³ (left panels a and b) or 10⁵ (right panels c and d) ffu/mouse were challenged with 10⁵ ffu/mouse of pathogenic Challenge Virus Strain-N2c and sera analyzed 3 and 5 days post-challenge by ELISA for anti-RABV G antibody recall responses as described in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002129#pntd-0002129-g001" target="_blank">Figure 1</a>. PBS-immunized IL-21R−/− and wild-type mice were also tested in parallel and a representative ELISA data is shown in panel e. B) Antibody titers for individual mice immunized with 10³ ffu/mouse rRABV and then challenged [from <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002129#pntd-0002129-g002" target="_blank">Figure 2A(b)</a>] are shown to indicate an antibody recall response against RABV G by day 3 post-challenge in a minimum number of IL-21R−/− mice. Mice that survived challenged are shown with a green icon, mice that did not survive challenge are shown with a red icon. Statistical difference in antibody titers by ELISA between two groups of data was determined using an unpaired, two-tailed t test and data is presented at the mean ± SEM. *p<0.05, **p = 0.01–0.001, ***p≤0.001. (N = 9–11 mice per group from two independent experiments). (p.c. = post-challenge; ffu = focus forming units; OD = optical density).