Clinical reactions after immunization and challenge
After immunization, none of the piglets in groups A1 (SD-R vaccine-treated and SD-challenge group) and A2 (SD-R vaccine-treated and HLJWK108-1711-challenge group) showed any clinical signs of PRRS compared to the negative control group and challenge control group. After challenge, none of the piglets in groups A1 (Fig. 2A, Fig. 3A) and A2 (Fig. 2B, Fig. 3B) showed significant changes in body temperature or weight loss. However, the piglets in group B1 (nonvaccinated and SD-challenge group) had various disease manifestations at 5 dpi, including fever persisting for 6-13 d (≥40.5℃) (Fig. 2A), and the piglets in group B2 (nonvaccinated and HLJWK108-1711-challenge group) had various disease manifestations as early as 1 dpi, including intermittent fever for 5-10 d (≥40.5℃) (Fig. 2B). In addition, the piglets in groups B1 and B2 had various levels of anorexia and emaciation. Compared to the negative control piglets in groups C1 and C2, the piglets in groups B1 and B2 gained less body weight (p <0.05) during 8-14 dpi and 15-21 dpi (Fig. 3A, Fig. 3B). In the course of the study, the piglets in groups C1 and C2 had no clinical signs of disease.