Synthesis of Newcastle disease virus (NDV)-like envelopes in insect cells infected with a recombinant baculovirus expressing the haemagglutinin-neuraminidase of NDV.

Electron microscopical examination of negatively stained extracellular fluids (ECF) from Spodoptera frugiperda cell cultures infected with a recombinant baculovirus expressing the Newcastle disease virus (NDV) haemagglutinin-neuraminidase (HN) revealed NDV-like envelopes which resembled the envelopes of authentic NDV. Immunogold staining with anti-NDV HN monoclonal antibodies demonstrated HN antigen in spikes on the NDV-like envelopes. The ECF from the recombinant-infected cultures also contained baculovirus particles which resembled standard baculovirus particles except that some showed polar protrusions of the envelope. It was concluded that the HN of NDV, in the absence of the matrix protein, might be able to initiate and control the production of viral envelopes which are morphologically identical to those of authentic NDV.