Evaluation of the LTK63 adjuvant effect on cellular immune responses to measles virus nucleoprotein
Department of Veterinary Parasitology and Microbiology, Makerere University, Kampala, Uganda; Department of Pathology and Infectious diseases, The Royal Veterinary College, London NW1, United Kingdom
Background: A lot of pathogens enter the body via the nasal route. The construction of non-toxic mutants of heat labile Escherichia coli enterotoxin (LT), which is a potent mucosal adjuvant, represents a major breakthrough for the development of mucosal vaccines. Objective: This study was undertaken to critically evaluate the adjuvanticity of the mutant of LT (LTK63) on the cellular immune responses to intranasally co-administered recombinant measles virus nucleoprotein (rMVNP). Methods: Groups of CBA mice were immunized intranasally with rMVNP with or without LT or LTK63 as adjuvants. Another group was immunized subcutaneously with rMVNP in Freund's adjuvant. rMVNP and measles virus (MV) were used in a proliferation assay to test the LTK63 potentiating ability to induce T cell responses. Subsequently MVNP synthetic peptides spanning the length of the N protein were used with a proliferation assay to identify the T cell epitopes. Results: Splenocytes from mice immunized intranasally with rMVNP plus LT or LTK63, showed strong dose dependent proliferative responses to both the MVNP and MV. However, proliferative responses from the latter group were significantly lower than the former group (P < 0.05). Splenocytes tested recognized peptides 20, 21, 28, 31, 39, 40 and 50, suggesting these to be among important epitopes. Subcutaneous route was not effective in priming for T cell responses to rMVNP. Conclusion: These data further demonstrate the great potential of LTK63 as a safe mucosal vaccine adjuvant.
epitope; Escherichia coli enterotoxin; Freund adjuvant; immunological adjuvant; ltk 63; mutant protein; recombinant measles virus nucleoprotein; unclassified drug; virus nucleoprotein; animal cell; animal experiment; antigen recognition; article; cellular immunity; controlled study; dose response; female; lymphocyte proliferation; measles; Measles virus; nonhuman; spleen cell; T lymphocyte; Adjuvants, Immunologic; Administration, Intranasal; Animals; Bacterial Toxins; Cell Proliferation; Enterotoxins; Epitopes; Escherichia coli; Escherichia coli Proteins; Female; Immunity, Cellular; Immunity, Mucosal; Measles virus; Mice; Mice, Inbred CBA; Nucleoproteins; Spleen; Vaccines; Viral Proteins