A method for tolerizing a mammalian subject to administration of a live virus carrying a gene for delivery to a cell of the subject is disclosed. The method entails administering to the subject a suitable amount of an inactivated virus prior to administration of the live virus. The prior administration of the inactivated virus suppresses anti-virus cytotoxic T cells, permitting longer transgene persistence once the live virus is administered, and permitting effective readministration of live virus.
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