Figure 4.

Cognitive deficits resolve in adult-infected mice but cognitive and myelin deficits persist long-term after juvenile H1N1 infection.

(A) Schematic illustration of experimental timeline. Mice were intratracheally inoculated at P14 with PBS or H1N1, and endpoint analyses were performed at P194, 6 months post-infection (MPI).

(B) Time spent in center of the open field over 10-minute testing period. Open field performed 6 months post-infection. n = 10 control, n = 12 H1N1 mice.

(C) Total distance moved in the open field over 10-minute testing period. Open field performed 6 months post-infection. n = 10 control, n = 12 H1N1 mice.

(D) Novel preference for NORT performed 6 months post-infection. n = 10 control, n = 12 H1N1 mice.

(E) Representative TEM images of mice infected with H1N1 during the juvenile period 6 months post-infection at the level of the cingulum of the corpus callosum in cross-section. Myelinated axons visible as electron-dense sheaths encircling axons.

(F) Quantification of myelinated axon density. n = 6 mice per group.

(G) G-ratio relative to small (<500 nm), medium (500–1000 nm), and large (>1000 nm) caliber axons for control (black points) or H1N1 (blue points) treated mice. n = 6 mice per group.

(H) Schematic illustration of experimental timeline. Mice were intratracheally inoculated at P60 with PBS or H1N1, and endpoint analyses were performed at P88, 4 weeks post-infection.

(I) Time spent in center of the open field over 10-minute testing period. Open field performed 4 weeks post-infection. n = 7 control, n = 8 H1N1 mice.

(J) Total distance moved in the open field over 10-minute testing period. Open field performed 4 weeks post-infection. n = 7 control, n = 8 H1N1 mice.

(K) Novel preference for NORT performed 4 weeks post-infection. n = 7 mice per group.

(L) Schematic illustration of experimental timeline. Mice were intratracheally inoculated at P60 with PBS or H1N1, and endpoint analyses were performed at P116, 8 weeks post-infection.

(M) Time spent in center of the open field over 10-minute testing period. Open field performed 8 weeks post-infection. n = 7 mice per group.

(N) Total distance moved in the open field over 10-minute testing period. Open field performed 8 weeks post-infection. n = 7 mice per group.

(O) Novel preference for NORT performed 8 weeks post-infection. n = 7 control, n = 6 H1N1 mice.

Data shown as mean ± SEM; each dot represents an individual mouse. ns: p > 0.05, * p < 0.05, analyzed via (B-D, F, I-K, N, and O) unpaired two-tailed t-test, (G) unpaired-t tests with correction for multiple comparisons, or (M) Mann-Whitney U test for datasets that failed the Shapiro-Wilk test. Scale bar (E), 1 μm.