title: Evaluation of infectious titer in a candidate HSV type 2 vaccine by a quantitative molecular approach.
abstract: BACKGROUND
  One of the critical tasks in analytical testing is to monitor and assign the infectivity or potency of viral based vaccines from process development to production of final clinical lots. In this study, a high throughput RT-qPCR based approach was developed to evaluate the infectious titre in a replication-defective HSV-2 candidate vaccine, called HSV529. This assay is a combination of viral propagation and quantitative RT-PCR which measures the amount of RNA in infected cells after incubation with test samples.
  
  
  RESULTS
  The relative infectious titre of HSV529 candidate vaccine was determined by a RT-qPCR method targeting HSV-2 gD2 gene. The data were analyzed using the parallel-line analysis as described in the European Pharmacopoeia 8th edition. The stability of HSV529 test samples were also investigated in a concordance study between RT-qPCR infectivity assay and a classical plaque assays. A suitable correlation was determined between both assays using an identical sample set in both assays. The RT-qPCR infectivity assay was further characterized by evaluating the intermediate precision and accuracy. The coefficient of variation from the six independent assays was less than 10%. The accuracy of each of the assay was also evaluated in the range of 92.91% to 120.57%.
  
  
  CONCLUSIONS
  Our data demonstrate that the developed RT-qPCR infectivity assay is a rapid high throughput approach to quantify the infectious titer or potency of live attenuated or defective viral-based vaccines, an attribute which is associated with product quality.
authors: Microbiology & Virology Platform, Department of Analytical Research & Development North America, Sanofi Pasteur, 1755 Steeles Avenue West, Toronto, Ontario M2R 3 T4, Canada. ali.azizi@sanofipasteur.com.
authors: Ali
authors: A
authors: Azizi
authors: Mei
authors: M
authors: Tang
authors: Lucy
authors: L
authors: Gisonni-Lex
authors: Laurent
authors: L
authors: Mallet
mesh_terms: D022301:Herpes Simplex Virus Vaccines / Q000592:standards*; D057166:High-Throughput Screening Assays / Q000379:methods; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D013678:Technology, Pharmaceutical / Q000379:methods*; D013997:Time Factors; D064166:Vaccine Potency; D019562:Viral Load / Q000379:methods*
chemical_list: D022301:Herpes Simplex Virus Vaccines; D012367:RNA, Viral