Fig. 6: Intrinsic pathogenicity of JN.1.7, KP.2, KP.3, and KP.3.1.1 in hamsters.
a Schematic of hamster infection and sample harvest. Golden hamsters were intranasally infected with 1 × 105 PFU JN.1, JN.1.7, KP.2, KP.3, or KP.3.1.1 (n = 5). Hamster lungs were harvested at 2 dpi for viral load detection or histological analysis. Created in BioRender. Zhu, R. (2025) https://BioRender.com/syp9nuf. b Viral gene copy detection in hamster lungs by RT-qPCR. RNA was extracted from homogenized hamster lungs, and RT-qPCR was conducted to detect the sgE and β-actin gene copies (n = 5). c Detection of infectious titer in infected hamster lungs by TCID50 assay. Homogenized hamster lung samples were 10-fold serial diluted to infect VeroE6-TMPRSS2 cells in 96-well plates (n = 5). Cellular cytopathic effect was recorded after 4 days of incubation to calculate the infectious titer. d, f Immunofluorescence staining of infected hamster lungs. Infected hamster lungs were embedded and sectioned, followed by immunostaining with SARS-CoV-2 nucleocapsid (N) protein antibody. Cell nuclei were labeled with DAPI stain (n = 5) (f). The fluorescence signal intensity was measured using ImageJ 1.53 (d). Scale bar, 200 μm. e, g Infected hamster lungs H&E staining and histological scoring. Sectioned hamster lungs were stained with hematoxylin and eosin. Images were taken under a microscope (g) and histological scoring was conducted based on the degree of tissue damage (n = 5) (e). Scale bar, 70 μm. The n number represents biological repeats. Data represent mean ± SEM. Statistical significance in (b–e) was determined with one-way ANOVA with post hoc Tukey’s multiple comparisons test. *p < 0.05, *** p < 0.001. ns represents not statistically significant. Source data are provided as a Source Data file.
