IBT Bioservices has developed several mouse models of IFV infection wherein mice are inoculated intranasally with an LD90 dose of virus. Test articles are administered per client instruction, and positive controls are available for comparison. Routine study endpoints include: lethality health score, weight, temperature, viral burden in lungs / BALF, cytokine response. IBT's challenge virus seeds are well characterized and lead to highly reproducible lethality rates. To demonstrate this characterization, a meta-analysis was performed on over 30 groups challenged with an LD90 of the IFV A/Texas/36/91 (H1N1) strain (~52 PFU). The result was an average 12.4% survival rate (very near the theoretical 10%) with a mean time to death of 8.2 days.