Quantitative determination of lentiviral vector particle numbers by real-time PCR

Here, we describe a quantitative, DNA-based real-time PCR approach to deter mine the number of lentivinis particles that are present in vector preparat ions. In this approach, the minus strong-stop cDNA fragment that is present In viral capsids serves as template for PCR. Using this technology, we fou nd that only 0.1%-1% of the virus particles that are present in vector prep arations are infectious. The approach described here is rapid, reliable, an d simple in concept and can be used to estimate both vector particles, in s upernatants and the number of infectious particles. Also, this approach can easily be adapted to a high-throughput system by using 96-well plates and a 2-h running time.