[Effect difference between two segments in invariant chain CLIP on humoral immune]

To compare the effect between two segments (PBS and GBS) of Class II -associated invariant chain peptide (CLIP) of invariant chain (Ii) on humoral immune by immune carrier.

First six hybrids containing Newcastle disease virus (NDV) epitope F2 and Ii segments (Cyt/TM/F2, Cyt/TM/F2/GBS, Cyt/TM/PBS/F2, Cyt/TM/F2/TRIM, Cyt/TM/F2/GBS/TRIM, Cyt/TM/PBS/F2/TRIM) were reconstructed respectively. Then they were inserted into the prokaryotic expression vector pET-32a and transformed into E. coli Rosetta (DE3) to induce the expression of the recombinant proteins. Finally mice were immunized with these purified fusion proteins, the specific antibody titers were detected with ELISA, to compare and analyze the effect among different groups on the immune response.

All the six groups immunized with these hybrids increased antibody titers (from 1.5-fold to 4.9-fold, respectively) compared with the group immunized with F2 alone. Within the above six groups, the hybrids containing either PBS or GBS had higher antibody titers from 1.6-fold to 2.4-fold than the hybrids without the both segments. However, the group of the hybrid containing PBS had a 1.5-fold antibody titer higher than the group of GBS hybrid.

Ii cytosolic and transmembrane domains could increase the immune response, while the segment PBS behaved better than GBS in an immune vector based on Ii.