SJL/J mice are highly susceptible to infection by mouse adenovirus type I

Mouse adenovirus type 1 (MAV-1) targets endothelial and monocyte/macrophage cells throughout the mouse. Depending on the strain of mouse and dose or s train of virus, infected mice may survive, become persistently infected, or die. We surveyed inbred mouse strains and found that for the majority test ed the 50% lethal doses (LD(50)s) were > 10(4.4) PFU. However, SJL/J mice w ere highly susceptible to MAV-1, with a mean LD50 of 10(-0.32) PFU. Infecte d C3H/HeJ (resistant) and SJL/J (susceptible) mice showed only modest diffe rences in histopathology. Susceptible mice had significantly higher viral l oads in the brain and spleen at 8 days postinfection than resistant mice. I nfection of primary macrophages or mouse embryo fibroblasts from SJL/J and C3H/HeJ mice gave equivalent yields of virus, suggesting that a receptor di fference between strains is not responsible for the susceptibility differen ce. When C3H/HeJ mice were subjected to sublethal doses of gamma irradiatio n, they became susceptible to MAV-1, with an LD50 like that of SJL/J mice. Antiviral immunoglobulin G (IgG) levels were measured in susceptible and re sistant mice infected by an early region IA null mutant virus that is less virulent that wild-type virus. The antiviral IgG levels were high and simil ar in the two strains of mice. Taken together, these results suggest that i mmune response differences may in part account for differences in susceptib ility to MAV-1 infection.