Amplified and tissue-directed expression of retroviral vectors using ping-pong techniques

M. E. Hoatlin, S. L. Kozak, C. Spiro, D. Kabat

Research output: Contribution to journalReview articlepeer-review

13 Scopus citations


Ping-pong amplification is an efficient process by which helper-free retrovirions replicate in cocultures of cell lines that package retroviruses into distinct hostrange envelopes [11]. Transfection of a retroviral vector DNA into these cocultures results in massive virus production, with potentially endless cross-infection between different types of packaging cells. Because the helperfree virus spreads efficiently throughout the coculture, it is unnecessary to use dominant selectable marker genes, and the retroviral vectors can be simplified and optimized for expressing a single gene of interest. The most efficient ping-pong vector, pSFF, derived from the Friend erythroleukemia virus, has been used for high-level expression of several genes that could not be expressed with commonly employed two-gene retroviral vectors. Contrary to previous claims, problems of vector recombination are not inherent to ping-pong methods. Indeed, the pSFF vector has not formed replication-competent recombinants as shown by stringent assays. Here we review these methods, characterize the ping-pong process using the human erythropoietin gene as a model, and describe a new vector (pSFY) designed for enhanced expression in T lymphocytes. Factors that limit tissue-specific expression are reviewed.

Original languageEnglish (US)
Pages (from-to)113-120
Number of pages8
JournalJournal of Molecular Medicine
Issue number3
StatePublished - Mar 1995
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery
  • Genetics(clinical)


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