Oral immunization with HCV-NS3-transformed Salmonella: induction of HCV-specific CTL in a transgenic mouse model.
OBJECTIVE
The ability to induce cytotoxic T cells is considered an important feature of a candidate hepatitis C virus (HCV) vaccine. We used an oral immunization strategy with attenuated HCV-NS3-transformed Salmonella typhimurium to deliver DNA directly to the gut-associated lymphoid tissue.


METHODS
HLA-A2.1 transgenic mice were immunized once with transformed attenuated Salmonella. HCV-specific CD8+ T cells were analyzed in vitro as well as in vivo by challenge of mice with recombinant HCV-NS3 vaccinia virus.


RESULTS
Salmonella (10(8) colony-forming units; 20 microg plasmid DNA) induced cytotoxic and IFN-gamma-producing CD8+ T cells specific for the immunodominant epitope NS3-1073 in 26 of 30 mice (86%) that persisted for at least 10 months. A second epitope (NS3-1169) was also recognized by cytotoxic and IFN-gamma-producing T cells, whereas a third one (NS3-1406) stimulated IFN-gamma production without cytotoxicity. The minimal amount of plasmid DNA required to induce CTLs was 2 ng. Upon challenge with recombinant HCV-NS3-expressing vaccinia virus, vaccinia titers were significantly lower in mice immunized with Salmonella-NS3 than in mice immunized with control Salmonella, demonstrating the in vivo function of CTLs.


CONCLUSIONS
Oral immunization with attenuated Salmonella typhimurium as a carrier for HCV DNA induces long-lasting T-cell responses.
Wedemeyer
H
H
Liver Diseases Section, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-1800, USA.
Gagneten
S
S
Davis
A
A
Bartenschlager
R
R
Feinstone
S
S
Rehermann
B
B
D000284:Administration, Oral; D000818:Animals; D015789:HLA-A2 Antigen / Q000276:immunology; D016174:Hepacivirus / Q000276:immunology*; D007114:Immunization; D007371:Interferon-gamma / Q000096:biosynthesis; D051379:Mice; D008822:Mice, Transgenic; D012486:Salmonella typhimurium / Q000235:genetics*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019444:Vaccines, DNA / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology*; D014761:Viral Hepatitis Vaccines / Q000276:immunology*; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000276:immunology; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D015789:HLA-A2 Antigen; D007371:Interferon-gamma; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; D014761:Viral Hepatitis Vaccines; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases