engleski

Reduction of hepatocyte transduction by fiber- modified adenoviruses following their strong uptake by Kupffer cells

Binding of blood factor X (FX) to Adenovirus (Ad) hexon protein was shown to be responsible for liver transduction. Unexpectedly we reported previously that an Ad5 pseudotyped with the shaft and fiber from serotype 3 (Ad5S3K3) was also impaired in its ability to drive hepatocyte transduction, thus questioning a potential role of fiber protein in Ad5 liver tropism. To better understand the role of fiber potein in Ad liver tropism, we compared Ad5S3K3 and an Ad pseudotyped with Ad3 fiber shaft (Ad5S3K5) to an Ad with unmodified capsid (Adwt). All three vectors were shown to bind to immobilized FX with similar efficacy but Ad5S3K3 and Ad5S3K5 were impaired in FX mediated transduction of CHO cells compared to Adwt. Following intravenous administration, a dose-dependent transgene expression was observed at day 2 post-infection (p.i.) for all three viruses. Interestingly, Ad5S3K3 but not Ad5S3K5 led to a reduced transgene expression at day 2 in liver compared to Adwt. In contrast, Q-PCR analyses performed at the same time point p.i. demonstrated a dramatic decrease in viral DNA content in liver for both Ad5S3K3 and Ad5S3K5. Remarkably, after Kupffer cell (KC) depletion either by pre-administration of Ad or by clodronate-liposomes, Ad5S3K3- and Ad5S3K5- injected mice displayed a liver transgene expression comparable to KC-depleted Adwt-injected mice. Finally, experiments are ongoing to confirm the role of FX in liver transduction by Ad5S3K3 and Ad5S3K5 in KC-depleted mice. Altogether, our results emphasize a role of fiber protein in controlling Ad distribution in the liver.

Fiber modified adenovirus; Adenovirus serotype 3; Factor X

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