Porcine reproductive and respiratory syndrome virus (PRRSV) is well known for its genetic variation and ability to change constantly,avoid host defense and establish a long-term infection.Although current vaccines can confer protection against homologous reinfection,their efficacy against heterologous infection is questionable.The objective of this study was to determine whether peptide hydrogel H9e can be used as an adjuvant for PRRS modified live virus (MLV) vaccine and its immunological mechanisms of adjuvanticity.Thirty-five pigs (3-weeks old) were divided into 7 groups (5 pigs/group) including PBS control groups,pigs vaccinated with Ingelvac PRRS MLV vaccine only,and pigs vaccinated with Ingelvac PRRS MLV vaccine adjuvanted with H9e hydrogel.