The paramyxovirus virus that lacks both hemagglutinin and neuraminidase activities is:

1. Influenza and mumps possess both haemagglutinin and neuraminidase spikes. 2. Measles possesses haemagglutinin but lacks neuraminidase spikes. 3. RSV lacks both haemagglutinin and neuraminidase spikes. The viral envelope contains a surface glycoprotein G, by which it is attached to the cell surface of the host cells. It contains F protein but lacks both H and N proteins. The F protein induces the fusion of the infected cells with adjoining cells, resulting in the formation of large multinucleated syncytia, from which the virus derives its name.