Laboratory preparation of Varicella-Zoster Virus: Concentration of virus-containing supernatant, use of a debris fraction and magnetofection for consistent cell-free VZV infections

The research laboratory generation of free Varicella-Zoster Virus (VZV) from cultured yields results relatively low titers, with the result that most study of VZV infection utilizes cell-associated infection. However, important aspects of VZV-cell interaction, such as the entry mechanism and superinfection exclusion have not yet been studied in detail, in part due to the difficulty in obtaining a high titer cell free virus. Here, a method to generate relatively high-titer cell-free VZV, based on a combination of previously published techniques and subsequent concentration is described. VZV-infected cells are disrupted, sonicated and clarified by centrifugation. The cell-free virus in the supernatant is then concentrated to yield up to 105 PFU/ml. The cell debris pellet, which contains up to 106 PFU/ml can also be used for non cell-associated infection. Magnetic nanoparticles available commercially can be used to further enhance infection by cell-free-VZV. The tools described here hold promise for better understanding of important aspects of VZV-cell interactions such as entry and latency.