Evaluation of the fusion type CpG adjuvant for the enhancement of somatostatin DNA vaccine in ram lambs

Abstract

Simple co-injection of CpG adjuvant and somatostatin (SS) DNA vaccine can enhance the effect of the vaccine and promote the growth of animals. This study investigated the enhancing effect of the fusion type of CpG motifs on SS DNA vaccine and growth of ram lambs. In this study, we constructed the ptS/2SS-asd plasmid, pCpG plasmid and the CpG-SS fusion type recombinant plasmid named ptCS/2SS-asd. Twelve ram lambs were randomly divided into three groups, namely, the treatment (Group T1, ptCS/2SSasd; Group T2, pCpG + ptS/2SS-asd) groups and the control (Group C, pVAX-asd). The vaccine (1 mg/ ram) was injected into the rams at weeks 0, 3 and 6 of the study. The rams in Group T1 and T2 showed significantly higher anti-SS antibody, serum growth hormone and IGF-1 concentrations and average body weight than those in the control group (P < 0.05). Immunisation with ptCS/2SS-asd promoted the growth of rams similar to the effect of the simple co-injection of CpG and SS DNA vaccine. Thus, the fusion type of CpG adjuvant is an effective, simple, and low-cost method in enhancing the effect of SS DNA vaccine and the growth of ram lambs.