Fig. 3.

Improved ribosomal skipping results in lethality more similar to WT NiV in vivo. (a) WT NiV and recombinant mCherry reporter viruses without (rNiV-mCh^M) or with (rNiV-mCh^M-opt) the GSG linker for optimal P2A skipping were used to inoculate groups of Syrian hamsters (n = 10 per group for each virus and dose combination, intraperitoneal route) at 10³ p.f.u. or 10⁴ p.f.u. per animal. Kaplan–Meier survival curves show no significant differences between WT NiV (○) and rNiV-mCh^M-opt (▾), whereas rNiV-mCh^M ( × ) exhibited significant attenuation relative to WT NiV that was most apparent at the higher inoculum used (P = 0.037, log-rank Mantel–Cox test). (b) Two hamsters were inoculated with rNiV-mCh^M-opt (10⁴ p.f.u., intraperitoneal route), and tissues were imaged ex vivo for mCherry fluorescence at 6 and 7 days p.i. using an IVIS Spectrum imaging platform. Data are displayed as radiant efficiency on a colour scale from 2 × 10⁷ (dark red) to 4.35 × 10⁷ (yellow). Gb, Gallbladder. White arrow indicates fluorescence in olfactory bulb. (c) Immunohistochemistry with anti-NiV-M was performed on lung and brain tissues from similarly infected hamsters. Arrows indicate examples of positive antigen staining. PA, Pulmonary artery; BR, bronchiole.