Made of lipid and proteins rarely glycoprotein

May be modified host plasma membrane or internal membranes

Projections from the envelope are known as spikes or peplomers

HIV virus uses its spikes for this purpose.

Viruses are infectious intracellular obligate parasites consisting of nucleic acid (RNA or DNA) enclosed in a protein coat called capsidIn some cases, a membranous envelope may be present outer to the capsidViruses are classified based on the presence or absence of this envelope around the protein coat1. Enveloped viruses eg: Herpes simplex, Chickenpox virus, Influenza virus etc2. Non-enveloped viruses eg: Adeno virus, parvovirus etc: attachment of the virus to the host cell.1. The outermost covering is the capsid made up of proteins2. Non enveloped viruses are more virulent and causes host cell lysis3. These viruses are resistant to heat, acids, and drying4. It can survive inside gastrointestinal tract5. It can retain its infectivity even after drying6. It will induce antibody production in the host7. Mode of transmission is through fecal or oral matter, formites and dust1. The outermost envelope is made up of phospholipids, proteins or glycoprotein which surround the capsid2. Enveloped viruses are less virulent often released by budding and rarely cause host cell lysis3. Are sensitive to heat, acids, and drying4. Generally it cannot survive inside gastrointestinal tract5. It lose its infectivity on drying6. It will induce both cell mediated and antibody mediated immune response in the host7. Mode of transmission is through blood or organ transplants or through secretions