Quantitative real-time PCR for titration of infectious recombinant AAV-2 particles

J Virol Methods. 2005 Jul;127(1):40-5. doi: 10.1016/j.jviromet.2005.03.006. Epub 2005 Apr 12.

Abstract

In this report, we present a fast, reliable and easy to perform method to quantify infectious titers of recombinant AAV-2 (rAAV-2) particles using the LightCycler technology, which is independent from the therapeutic transgene and without the presence of a marker gene. The method is based on the life cycle of AAV-2: after infection of the host cell, the single stranded (ss) AAV-2 genome is converted into a double stranded (ds) form. Following infection with rAAV-2, HeLa cells were lysed and ssDNA of transcriptionally inactive particles were efficiently removed by ssDNA-specific S1 nuclease digestion. The remaining viral dsDNA can be quantified by quantitative real-time PCR (qPCR). For validation of the new method, rAAV-2 preparations were analyzed by two other standard methods for titration of infectious particles in parallel, i.e. the infectious center assay (ICA) as well as flow cytometry using GFP as a marker. Comparing the infectious titers of 40 different AAV-2 fractions assessed by qPCR with the titers determined by FACS analysis a significant correlation (r=0.87, p<0.001) with a mean ratio of the titers assessed by qPCR and FACS of 1.92 (S.D.+/-1.59) was found. Further, the titers of seven rAAV-2 fractions using qPCR and ICA covering 5 log ranges were compared and a significant correlation was found between the results (r=0.80, p<0.001) with a mean ratio of 3.38 (S.D.+/-1.79), respectively.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • DNA, Single-Stranded / analysis
  • DNA, Single-Stranded / metabolism
  • DNA, Viral / analysis
  • DNA, Viral / metabolism
  • Dependovirus / genetics
  • Dependovirus / isolation & purification*
  • Dependovirus / metabolism
  • Genetic Vectors / genetics
  • Genetic Vectors / isolation & purification*
  • Humans
  • Polymerase Chain Reaction / methods*
  • Polymerase Chain Reaction / standards
  • Reproducibility of Results
  • Single-Strand Specific DNA and RNA Endonucleases
  • Virus Replication

Substances

  • DNA, Single-Stranded
  • DNA, Viral
  • Single-Strand Specific DNA and RNA Endonucleases