<P> Some viruses ( e.g. HIV and many animal viruses ) have viral envelopes covering their protective protein capsids . The envelopes are typically derived from portions of the host cell membranes ( phospholipids and proteins ) , but include some viral glycoproteins . They may help viruses avoid the host immune system . Glycoproteins on the surface of the envelope serve to identify and bind to receptor sites on the host 's membrane . The viral envelope then fuses with the host 's membrane , allowing the capsid and viral genome to enter and infect the host . </P>
<P> Some viruses ( e.g. HIV and many animal viruses ) have viral envelopes covering their protective protein capsids . The envelopes are typically derived from portions of the host cell membranes ( phospholipids and proteins ) , but include some viral glycoproteins . They may help viruses avoid the host immune system . Glycoproteins on the surface of the envelope serve to identify and bind to receptor sites on the host 's membrane . The viral envelope then fuses with the host 's membrane , allowing the capsid and viral genome to enter and infect the host . </P>
what is the origin of a viral envelope
what is the origin of a viral envelope
portions of the host cell membranes ( phospholipids and proteins )
portions of the host cell membranes ( phospholipids and proteins )