Fig. 2

PR8_HA(H2) does not replicate nor cause pathogenesis in Tmprss2^−/− mice. Female C57BL/6 J wild type (WT) and Tmprss2^−/− knock-out (KO) mice (8–12 weeks old) were infected intranasally with 2 × 10⁴ focus forming units (ffu) PR8_HA(H2) (H2N1). Body weight was monitored for 14 days post infection (dpi; WT: n = 12; KO: n = 10). a Mean body weight in percent of starting weight ± 1 standard error of mean (SEM). b Survival curve. Statistics for survival curve was calculated with the log rank test. ns: non-significant. c Viral load in lung at 2 (WT: n = 7; KO: n = 7) and 4 dpi (WT: n = 8; KO: n = 9). Mean titers are shown ±1 SEM. The detection limit for the ffu assay was 40. Undetectable titers were set to 1. d Mean (grey) ± 1 SEM of the relative lung weight (lung weight*100/body weight) determined on 2 (WT: n = 8; KO: n = 8; mock (m2): n = 5) and 4 dpi (WT: n = 8; KO: n = 9). e On 2 dpi (WT d2: n = 13; KO d2: n = 13; mock m d2: n = 5) and 4 dpi (WT d4: n = 17; KO d4: n = 21), eye blood was collected. Cell types (lymphocytes, monocytes and granulocytes) were phenotyped and counted based on cell volume using the VetScan HM5 hematologic system. Cell types are presented in percentage of total white blood cells (WBC). Mock samples were collected from WT mice. To note, we did not compare basal cell counts in KO versus WT since a difference is not expected, although it cannot be excluded. Bars represent mean values, error bars show ±1 SEM. Statistics for (c) and (d) were calculated by Mann Whitney Tests (** p < 0.01; *** p < 0.001)