GPT and infection: The average AST, ALT, and LDH levels in sera of chickens in NZ9000/pTX8048, MDXEF-1/pTX8048 group, and infection control group were transiently and significantly elevated on 4 dpi compared to PBS control group and four ΔHexon-expressing bacteria groups, which indicating that severe pathological changes have occurred in liver (43).