Virus Replication

Hsiao-Sheng Liu 劉校生 

國立成功大學微生物暨免疫學研究所

The objectives:

• How to calculate virus titer?

• One step growth curve

• The general stages of viral replication cycle

• Attachment, penetration and release of the viruses

How to measure virus titer?

Baculovirus plaques

Zones of clearing (plaques) are generated by infection of insect (Sf9} cells with individual baculovirus particles. Uninfected Sf9 cells surrounding the plaque are stained pink with neutral red.

10-6 10-7

PFU: plaque forming unit 1 PFU = 1 plaque = 1 bacterial phageCount : plaque 數量  x 稀釋倍數  x 10/9 = PFU/ml

Ex: 211 x 107 x 10/9 = 2.34 x 109 PFU/ml

211 plaques

What is one step growth curve?

陰蔽期潛伏期

What are the general stages in viral replication cycles?

General replicationprocedure

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© 2005 Elsevier

Complicated replicationprocedure (e.g. Herpes virus)

How the viral replication cycle is known?

Attachment: receptor, tissue tropism

HA: Hemagglutinine

Trimmers of HA on influenza virus membrane

Coreceptor: CCR5 CRCX4

CCR5: macrophage-tropic HIV

CXCR4: lymphocyte-tropic HIV

How does the virus enter the cell?

Endocytosis

Fusion

Pinocytosis (Viropexis)

Paramyxovirus fusion Syncytia

Togavirus

How is the virus released from the cell?

Orthomyxoviruswith M protein Herpes virus

Respiratory syncytial virus budding

Brooks et al, 1998