Methods: Children of 1-15 years of age received single dose of live attenuated SA-14-14-2 JE vaccine under JE vaccination drive (April 2014 to May 2014) were enrolled for this study. Blood samples from 149 children were collected on day 0 (pre- vaccination) and day 28 post-vaccination. Neutralizing anti-JE virus antibody titer were assessed in serum by plaque reduction neutralization test (PRNT). Further percentage of T cell subset CD3+, CD8+, CD4+ IFN-γ+ , CD4+ IL-4+, CD4+ IL-17+and CD4+CD25+ TReg in children belongs to non responders and high titer group were determined by flow cytometry. Plasma level of various cytokine IFN- γ, IL-4, IL-17, TGF-β and IL-10 were measured by ELISA
Results:23(15.43 %) children were found to be non responder (PRNT <10) and 30 (20.13%) were found to be of high antibody titer group (PRNT>320). Higher percentage of Treg cell was found in non responder (2.44± 0.19%) when compare to high titer group (0.812± 0.14%) ( p<0.001). Moreover significant increased expression of TGF-β was also found in non responder than high titer group. (p=0.002).
Conclusion:This study indicates that Treg cells expansion have role in down regulating the antibody response to Japanese Encephalitis vaccination. Increased expression of TGF-β in non responder seems to stimulate additional Treg production. Further studies are needed to evaluate if removing dominant Treg epitopes could improve the immunogenicity and developing an effective JE vaccine strategy in future.
S. Saxena, None
S. Ghildiyal, None
M. Baluni, None
J. Umrao, None
T. Dhole, None