Panel A shows an experimental schematic where mice were immunized with either LAIV-WT or LAIV-SenNP and then co-housed with Sendai-Luc infected index mice, with some mice treated with FTY720 or PBS control. Panel B presents bioluminescence curves for LAIV-WT, LAIV-SenNP with PBS, and LAIV-SenNP with FTY720 contact mice, showing the log10 flux over days post-exposure. Panel C is a bar graph showing the probability of infection for immunized contact mice. Panel D shows another experimental schematic where MT minus slash minus mice were immunized with LAIV-WT or LAIV-SenNP prior to co-housing with Sendai-Luc infected index mice. Panel E presents bioluminescence curves for MT minus slash minus mice immunized with LAIV-WT and LAIV-SenNP, showing the log10 flux over days post-exposure. Panel F is a bar graph showing the probability of infection for MT minus slash minus contact mice. Panel G shows an experimental schematic where mice were immunized with LAIV-WT or LAIV-SenNP and treated with isotype or anti-CD4 depleting antibodies before co-housing with Sendai-Luc infected index mice. Panel H presents bioluminescence curves for mice immunized with LAIV-WT, LAIV-SenNP with isotype antibody, and LAIV-SenNP with anti-CD4 antibody, showing the log10 flux over days post-exposure. Panel I is a bar graph showing the probability of infection for isotype and anti-CD4 treated mice immunized with LAIV-WT or LAIV-SenNP. Solid dark lines represent means, solid pale lines represent individual mice, dashed grey lines represent the limit of detection, and dashed red lines represent the threshold of infection.
Circulating effector cells, B cells, and CD4 T cells are dispensable for protection against transmission even when a lower quantity of respiratory tract TRM are present. (A) Experimental schematic where LAIV-WT i.n. or LAIV-SenNP i.n. immunized contact mice were co-housed with Sendai-Luc–infected index mice and treated with FTY720 or PBS control i.p. (B) Bioluminescence curves of LAIV-WT i.n. (n = 11), LAIV-SenNP i.n. with PBS (n = 15), and LAIV-SenNP i.n. with FTY720 (n = 15) contact mice following co-housing with index mice. (C) Probability of infection for immunized contact mice, calculated as the proportion of contact mice that became infected. (D) Experimental schematic where μMT−/− mice were immunized i.n. with LAIV-WT or LAIV-SenNP prior to co-housing with Sendai-Luc–infected index mouse. (E) Bioluminescence curves of μMT−/− mice immunized with LAIV-WT (n = 9) and LAIV-SenNP (n = 16). (F) Probability of infection for μMT−/− contact mice immunized with LAIV-WT and LAIV-SenNP. (G) Experimental schematic where LAIV-WT i.n. or LAIV-SenNP i.n. immunized contact mice were treated with isotype or anti-CD4–depleting antibodies and co-housed with Sendai-Luc–infected index mice. (H) Bioluminescence curves of mice immunized with LAIV-WT (n = 16), LAIV-SenNP and treated with isotype antibody (n = 16), and LAIV-SenNP and treated with anti-CD4 antibody (n = 16). (I) Probability of infection for isotype- and anti-CD4–treated mice immunized with LAIV-WT or LAIV-SenNP. For B, E, and H, solid dark lines represent means, solid pale lines represent individual mice, dashed grey lines represent the limit of detection, and dashed red lines represent the threshold of infection. Error bars (C, F, and I) represent 95% binomial confidence intervals. All data are combined from two independent replicates. Statistical significance was determined using a two-sided Mann–Whitney test with *P < 0.05, **P < 0.01, ***P < 0.001, and NS for not significant.