GPT and infection: Serum levels of two liver enzymes, alanine aminotransferase (ALT) and aspartate transaminase (AST), were significantly elevated in MBT mice on day 3 post infection (median values 2844 and 3032 U/L, respectively), by comparison with uninfected controls (80 and 292 U/L, respectively; Mann-Whitney U test, p < 0.01 for both), suggesting an early onset of liver dysfunction.