FIG 4.

HMPV VLPs induce a CD3⁺ T cell infiltrate in the lungs of immunized animals after an HMPV challenge. At day 33 (5 days after an HMPV challenge), slices were collected from the left lung of each vaccinated mouse. Lung samples were fixed, paraffin embedded, sectioned at a 5-μm thickness, and stained with anti-CD3 antibody. (A) Lung samples were analyzed and scored for CD3⁺ T cell infiltration on a scale of 0 to 3. Infiltrate scores (mean ± SEM) of two mice from each group are shown. Comparisons of multiple groups were made by one-way ANOVA with Dunnett's posttest. No significant differences were noted. (B) Digital images of the CD3-stained lung sections were generated with an Aperio ScanScope CS2, and a color deconvolution algorithm was used to quantify CD3 staining. Ten random regions, covering the entire lung area, from two mice per group were chosen, and the CD3⁺ area of each region was calculated. Results are presented as the mean ± the SEM. Comparisons of multiple groups were made by one-way ANOVA with Dunnett's posttest (*, P < 0.05). (C to H) Representative images of lung sections from immunized or infected mice at 5 days after an HMPV challenge. Magnification, ×20. CD3⁺ T cells are stained dark brown. Scale bars are shown in the lower left corners.