Newly-developed Sendai virus vector for retinal gene transfer: reduction of innate immune response via deletion of all envelope-related genes.
BACKGROUND
Recombinant Sendai virus vectors (rSeV) constitute a new class of cytoplasmic RNA vectors that have shown efficient gene transfer in various organs, including retinal tissue; however, the related immune responses remain to be overcome in view of clinical applications. We recently developed a novel rSeV from which all envelope-related genes were deleted (rSeV/dFdMdHN) and, in the present study, assess host immune responses following retinal gene transfer.


METHODS
rSeV/dFdMdHN or conventional F-gene deleted rSeV (rSeV/dF) was injected into subretinal space of adult Wistar rats or C57BL/6 mice. The transgene expression and histopathological findings were assessed at various time points. Immunological assessments, including the expression of proinflammatory cytokines, natural killer (NK)-cell activity, as well as SeV-specific cytotoxic T lymphocytes (CTLs) and antibodies, were performed following vector injection.


RESULTS
rSeV/dFdMdHN showed high gene transfer efficiency into the retinal pigment epithelium at an equivalent level to that seen with rSeV/dF. In the early phase, the upregulation of proinflammatory cytokines, local inflammatory cell infiltration and tissue damage that were all prominently seen in rSeV/dF injection were dramatically diminished using rSeV/dFdMdHN. NK cell activity was also decreased, indicating a reduction of the innate immune response. In the later phase, on the other hand, CTL activity and anti-SeV antibodies were similarly induced, even using rSeV/dFdMdHN, and resulted in transient transgene expression in both vector types.


CONCLUSIONS
Deletion of envelope-related genes of rSeV dramatically reduces the vector-induced retinal damage and may extend the utility for ocular gene transfer; however, further studies regulating the acquired immune response are required to achieve long-term transgene expression of rSeV.
Murakami
Yusuke
Y
Department of Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Ikeda
Yasuhiro
Y
Yonemitsu
Yoshikazu
Y
Tanaka
Sakura
S
Kondo
Haruhiko
H
Okano
Shinji
S
Kohno
Ri-Ichiro
R
Miyazaki
Masanori
M
Inoue
Makoto
M
Hasegawa
Mamoru
M
Ishibashi
Tatsuro
T
Sueishi
Katsuo
K
D000818:Animals; D016923:Cell Death; D016207:Cytokines / Q000378:metabolism; D003588:Cytopathogenic Effect, Viral; D017353:Gene Deletion; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007113:Immunity, Innate / Q000276:immunology*; D018836:Inflammation Mediators / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017208:Rats, Wistar; D010253:Respirovirus Infections; D012160:Retina / Q000166:cytology / Q000378:metabolism* / Q000821:virology; D029082:Sendai virus / Q000235:genetics*; D013997:Time Factors; D014161:Transduction, Genetic / Q000379:methods*; D019076:Transgenes; D014759:Viral Envelope Proteins / Q000235:genetics*
D016207:Cytokines; D018836:Inflammation Mediators; D014759:Viral Envelope Proteins; D049452:Green Fluorescent Proteins