In order to determine the impact of pathogenic Litopenaeus vannamei, shrimps with weights of (2.2±0.24) g were challenged with Vp at a concentration of 5×10⁷ CFU/mL for 36 h. The hepatopancreas tissues from the experimental and control groups were collected at 6 h, 12 h, 24 h, and 36 h after the start of the experiment to evaluate antioxidant enzyme activities and immune and mTOR signal pathway-related gene expression levels. The results showed that after challenge with Vp, SOD activity was significantly higher than that of the control group (<0.05), while CAT, GSH-PX, and GST activities all increased at first and subsequently decreased, reaching the peak value at 12 h, 6 h and 24 h, respectively ( were significantly higher than in the control group ( were up-regulated at first and then decreased after reaching their peaks at 12 h and 24 h, respectively, while the level of the gene was significantly lower than that of the control group during the time 12-36 h (< 0.05). These results showed that functions of the immune system were affected by Vp. Several important genes in mTOR signal pathway were also been quantified by qRT-PCR. The relative expression levels of P<0.05). were both up-regulated at first and then decreased after reaching peak values at 12 h and 6 h, respectively ( was significantly lower than that of the control group after challenge (<0.05). The results indicated that Vp challenge had a noticeable impact on antioxidant enzyme activities and immune and mTOR signal pathway-related gene expression of , with significant destructive effect on the shrimp's immune system.