Enhanced mortality and liver damage in virus-infected mice exposed to p-xylene

This study assessed effects of exposure to p‐xylene, a ubiquitous air pollutant, on mice infected with murine cytomegalovirus (MCMV), a mouse model for a common human virus. It was postulated that adverse health effects could occur as a result of (1) enhanced infection due to xylene‐induced immune suppression, (2) increased p‐xylene toxicity due to viral suppression of cytochrome P‐450 (P‐450), and/or (3) additive or synergistic effects on liver function due to tissue injury by both p‐xylene and MCMV. Mice were exposed to filtered air, 600 or 1200 ppm p‐xylene 6 h/d for 4 d and infected with a sublethal dose of MCMV after the first exposure. No deaths occurred among uninfected, p‐xylene‐exposed mice or infected, air‐exposed mice; 34% and 0% mortality occurred respectively in infected mice exposed to 1200 and 600 ppm p‐xylene. Virus titers in the liver and splenic natural killer cell activity were unaffected by exposure to 1200 ppm p‐xylene. Small but significant increases in serum aspartate aminotransfera...