Engineering the vaccinia virus L1 protein for increased neutralizing antibody response after DNA immunization.
BACKGROUND
The licensed smallpox vaccine, comprised of infectious vaccinia virus, has associated adverse effects, particularly for immunocompromised individuals. Therefore, safer DNA and protein vaccines are being investigated. The L1 protein, a component of the mature virion membrane that is conserved in all sequenced poxviruses, is required for vaccinia virus entry into host cells and is a target for neutralizing antibody. When expressed by vaccinia virus, the unglycosylated, myristoylated L1 protein attaches to the viral membrane via a C-terminal transmembrane anchor without traversing the secretory pathway. The purpose of the present study was to investigate modifications of the gene expressing the L1 protein that would increase immunogenicity in mice when delivered by a gene gun.


RESULTS
The L1 gene was codon modified for optimal expression in mammalian cells and potential N-glycosylation sites removed. Addition of a signal sequence to the N-terminus of L1 increased cell surface expression as shown by confocal microscopy and flow cytometry of transfected cells. Removal of the transmembrane domain led to secretion of L1 into the medium. Induction of binding and neutralizing antibodies in mice was enhanced by gene gun delivery of L1 containing the signal sequence with or without the transmembrane domain. Each L1 construct partially protected mice against weight loss caused by intranasal administration of vaccinia virus.


CONCLUSIONS
Modifications of the vaccinia virus L1 gene including codon optimization and addition of a signal sequence with or without deletion of the transmembrane domain can enhance the neutralizing antibody response of a DNA vaccine.
Shinoda
Kaori
K
Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-3210, USA. shinodak@niaid.nih.gov
Wyatt
Linda S
LS
Irvine
Kari R
KR
Moss
Bernard
B
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D019470:Biolistics; D005260:Female; D005818:Genetic Engineering / Q000379:methods*; D006801:Humans; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D012900:Smallpox Vaccine / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014615:Vaccinia / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D014616:Vaccinia virus / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
D000914:Antibodies, Viral; C087715:L1R protein, Vaccinia virus; D012900:Smallpox Vaccine; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins