FIG 1.

Challenge of CBA mice with the attenuated EHV-1 strain KyA or the pathogenic strain RacL11. (A) The Kentucky A (KyA) strain of EHV-1 lacks the genes encoding gI and gE and is attenuated in both equines and mice. —, no deletion. (B and C) Average body weights (B) and percentages of survival (C) of CBA mice infected with KyA or RacL11. Groups of CBA mice (n = 8) were infected intranasally with 2 × 10⁶ PFU/mouse of KyA or 1.5 × 10⁶ PFU/mouse of RacL11, which is the standard protocol used in our previous publications (14, 17, 19). Mice were monitored daily for clinical signs of infection, weight gain or loss, and morbidity.