Artificial Assembly of Envelope Particles of HVJ (Sendai Virus). Fusion Activity of Envelope Particles

Abstract

Summary An assay system for fusion activity of envelope particles of Sendai virus, reassembled from NP40-solubilized envelopes, was established and conditions for the artificial assembly of NP40-solubilized Sendai virus envelope particles with haemolytic and fusion activities were investigated. Large (GP1) and small (GP2) glycoproteins and lipids seemed to be required for the expression of haemolytic and fusion activities of envelope particles. Potential haemolysin activity was associated with GP2. A relatively high proportion of GP1 was required for formation of envelope particles with a high fusion activity. When the top lipid fraction (Hosaka & Shimizu, 1972a) was used for reassembly, the envelope particles usually exhibited both fusion and haemolytic activities but the optimal concentrations of the lipid for the two activities were different. An unidentified factor extractable with NP40 seemed to be necessary for fusion activity but not for haemolytic activity.