a, Primary SARS-CoV-2 challenge schematic. Two groups of male hamsters (N=4) were challenged with 105 plaque forming units (PFU) of either SARS-CoV-2 WT or ΔPRRA mutant and evaluated (b) weight loss, (c) disease score, (d) viral titer from nasal wash and (e) viral RNA from oral swabs. f-k, Twenty eight DPI, hamsters infected with SARS-CoV-2 WT or ΔPRRA were rechallenged with 105 PFU of SARS-CoV-2 WT and evaluated for (f) weight loss, (g) viral titer from nasal wash, (h) viral RNA from oral swabs, and (i) PRNT50 dilution from primary and rechallenge hamster sera. Data presented as mean values +/− SEM. P-values based on a two-tailed Student T-test.