Page 97 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

Viral replication

 Replication between viruses is greatly varied and depends on the type of

genes involved in them. Most DNA viruses assemble in the nucleus while

most RNA viruses develop solely in cytoplasm
1- Adsorption

• Attachment of the virus to the host cell by

interaction between specific proteins on viral

surface and specific receptors on target cell

membrane

2- Penetration

• Passage of the virion from the surface of the cell, across cell membrane →

cytoplasm.

(a) Direct penetration: Some naked viruses (e.g.

poliovirus)

(b) Fusion of virus envelope with cell membrane: Ex:

measles, influenza.

(c) Endocytosis: through engulfment by

receptor-mediated endocytosis and form

coated vesicles.

General Microbiology & Immunology (PM 401) theoretical handbook Page 86