Fig. 7From: The replicase protein nsp2 of Chinese highly pathogenic porcine reproductive and respiratory virus is involved in protective immunity by promoting viral clearanceThe effect of exchange of SP and nsp2 on induction of humoral immunity. A The serum antibody dynamics from infected piglets by an IDEXX HerdChek PRRS X3 ELISA kit. S/P ≥ 0.4 was considered seropositive. B The serum NA titer at 42 DPI titrated in MARC-145 cells. C The serum NA titer at 63 DPI titrated in MARC-145 cells. Error bars represent standard deviation (SD). Asterisks mean the statistical difference between infected groups (*, P < 0.05; **, P < 0.01; ***, P < 0.001)Back to article page