The rate at which retroviral vectors bind to and infect cells is mostly controlled by diffusion. During retrovirus infection, only a small fraction of the retroviral vectors can transduce target cells. Virion adsorption is the limiting step of this process. The use of polycations, such as Polybrene, is standard in many retroviral infection protocols owing to the observations of improved infection efficiency. Its mechanism of action is thought to involve neutralization of electrostatic repulsion between virion and cell membranes, enhancing attachment. ViraDuctin™ Retrovirus Transduction Kit is a proprietary formulation for the transduction of retrovirus. After forming a complex with retrovirus in culture medium, the ViraDuctin™ reagents typically provide higher transduction efficiency in many cell types compared to reagents such as Polybrene. It is ideal for transduction of nonpermissive cells such as primary cells and stem cells. 40 transductions.