Figure 6.
Evaluation of protection against SARS-CoV-2-induced lung pathology
Syrian hamsters were immunized via intramuscular and oral routes. The intramuscular injection consisted of a single dose of 2 × 107 CFU, whereas the oral route of administration consisted of two doses of 2 × 108 CFU at a 2-week interval. Hamsters were challenged 3 weeks after the final immunization with 1 × 104 PFU of either parental strain (clade L) or delta variant (clade G). (A) Gross and (B) H&E-stained lung images from hamsters challenged with parental SARS-CoV-2 at day 5 post-challenge. Each image is representative of a group of two hamsters. (C) Gross and (D) H&E-stained lung images from hamsters challenged with B.1.617.2 SARS-CoV-2 at day 5 post-challenge. Each image is representative of a group of four hamsters. Infected lung tissue sections showing the characteristic lesion of interstitial pneumonia (red circle), perivascular cuffing (black arrowhead), and congestion (red arrowhead).