Final answer:
The lipid-containing envelope of many animal viruses is derived from the host cell's plasma membrane. This envelope plays a critical role in the infection process by aiding in the entry of the virus into new host cells and helps in evading the host's immune response.
Step-by-step explanation:
The Lipid-Containing Envelope of Viral Capsids:
The lipid-containing outer envelope surrounding the viral capsid of many animal viruses is derived from the host cell's plasma membrane. When viruses exit the host cell, they can bud from the plasma membrane, incorporating a portion of the membrane into their structure, forming the envelope. This envelope contains not only lipids but also proteins and carbohydrates, with the proteins often coded by both the viral and host genomes.
Enveloped viruses such as influenza virus, HIV, and varicella zoster virus benefit from this lipid bilayer as it assists in the infection process, specifically in the fusion method of entry whereby the viral envelope fuses with the plasma membrane of the host cell.
While some viruses use internal membranes such as the nuclear membrane or endoplasmic reticulum to form their envelope, the primary source cited for the viral envelopes of many animal viruses is the plasma membrane of the host cell.