Propagation of Brazilian Zika virus strains in static and suspension cultures using Vero and BHK cells.
The recent spread of Zika virus (ZIKV) in the Americas and the Pacific has reached alarming levels in more than 60 countries. However, relatively little is known about the disease on a virological and epidemiological level and its consequences for humans. Accordingly, a large demand for in vitro derived Brazilian ZIKV material to support in vitro and in vivo studies has arisen. However, a prompt supply of ZIKV and ZIKV antigens cannot be guaranteed as the production of this virus typically using Vero or C6/36 cell lines remains challenging. Here we present a production platform based on BHK-21 suspension (BHK-21SUS) cells to propagate Brazilian ZIKV at larger quantities in perfusion bioreactors. Scouting experiments performed in tissue culture flasks using adherent BHK-21 and Vero cells have demonstrated similar permissivity and virus yields for four different Brazilian ZIKV isolates. The cell-specific yield of infectious virus particles varied between respective virus strains (1-48PFU/cell), and the ZIKV isolate from the Brazilian state Pernambuco (ZIKVPE) showed to be a best performing isolate for both cell lines. However, infection studies of BHK-21SUScells with ZIKVPEin shake flasks resulted in poor virus replication, with a maximum titer of 8.9×103PFU/mL. Additional RT-qPCR measurements of intracellular and extracellular viral RNA levels revealed high viral copy numbers within the cell, but poor virus release. Subsequent cultivation in a perfusion bioreactor using an alternating tangential flow filtration system (ATF) under controlled process conditions enabled cell concentrations of about 1.2×107cells/mL, and virus titers of 3.9×107PFU/mL. However, while the total number of infectious virus particles was increased, the cell-specific yield (3.3PFU/cell) remained lower than determined in adherent cell lines. Nevertheless, the established perfusion process allows to provide large amounts of ZIKV material for research and is a first step towards process development for manufacturing inactivated or live-attenuated ZIKV vaccines.
Max Planck Institute for Dynamics of Complex Technical Systems, Bioprocess Engineering, Sandtorstr. 1, 39106 Magdeburg, Germany. Electronic address: nikolay@mpi-magdeburg.mpg.de.
Alexander
A
Nikolay
Federal University of Rio de Janeiro, COPPE, Cell Culture Engineering Laboratory, Cx. Postal 68502, Ilha do Fundao, 21941-972 Rio de Janeiro/RJ, Brazil. Electronic address: leda@peq.coppe.ufrj.br.
Leda R
LR
Castilho
Max Planck Institute for Dynamics of Complex Technical Systems, Bioprocess Engineering, Sandtorstr. 1, 39106 Magdeburg, Germany; Chair for Bioprocess Engineering, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany. Electronic address: ureichl@mpi-magdeburg.mpg.de.
Udo
U
Reichl
Max Planck Institute for Dynamics of Complex Technical Systems, Bioprocess Engineering, Sandtorstr. 1, 39106 Magdeburg, Germany. Electronic address: genzel@mpi-magdeburg.mpg.de.
Yvonne
Y
Genzel
D000818:Animals; D019149:Bioreactors; D002452:Cell Count; D018929:Cell Culture Techniques / Q000379:methods*; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D014709:Vero Cells; D019562:Viral Load; D014765:Viral Vaccines; D014776:Virus Cultivation / Q000379:methods*; D014779:Virus Replication; D000071244:Zika Virus / Q000254:growth & development* / Q000502:physiology
D014765:Viral Vaccines
BHK-21; Brazilian Zika virus; High cell density; Perfusion process; Process intensification; Suspension cell line