Page 99 - MNU microbiology theoritical 2025

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

• New viral proteins move to nucleus where they combine with new DNA to

form new viruses

• Exception - Poxviruses synthesize their parts in host cell’s cytoplasm

b) RNA viruses:

• “+” sense RNA acts as mRNA - viral proteins are made immediately in

cytoplasm mediated by viral enzymes

• “-” sense RNA (e.g. influenza) - lst makes a “+” sense RNA copy via viral

enzyme

6- Assembly (maturation)

• Assembly of viral nucleic acid and protein coats → mature virus.

• Occurs in cell nucleus, cytoplasm or (with most enveloped viruses) at the

plasma membrane

➢ Cytoplasm, e.g. poliovirus.

➢ Nucleus, e.g. herpsvirus.

7- Release

A- Non-enveloped virus: rupture of cell membrane – release of mature particles.

B- Enveloped virus: release of virus by budding through outer cell membrane.

General Microbiology & Immunology (PM 401) theoretical handbook Page 88