Page 100 - MNU microbiology theoritical 2025

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

Viral Growth Curve

The one-step growth curve begins with the eclipse period, which is followed by

a period of exponential growth

1) Eclipse phase: the period during which the virus becomes uncoated and no

infectious virus particles are detected inside the cell.

2) Latent period: during which new virus particles are assembled inside the cells

but no extracellular virus particles are detected. (eclipse + maturation)

3) Rise period (brust): when the viruses

are released and increase in count.

Burst size: number of virions

produced per infected cell (10-10,000)

Effect of viral growth on infected cells

1-Lytic cycle:

 It results in the destruction (lysis and death) of the infected cells.

 The viral genome exists as a separate molecule within the bacterial cell and

replicates separately from the host bacterial DNA.

 When the cell becomes filled with viruses, lysis occurs and new viruses are

free to infect other cells

 Viruses of the lytic cycle are called virulent viruses

General Microbiology & Immunology (PM 401) theoretical handbook Page 89