Virus - Infection Flashcards
What are the four ways viruses can infect?
Latent
Persistent
Lysis
Transformationq
What does transformation infection lead to?
Tumor cells with oncogenic virus development
What is the process of transformation?
The virus carrying oncogenes with capacity for cancer by altering host behaviour
What is the general infection cycle?
Binding surface of a host, receptor-ligand interactions, membrane fusion or receptor-mediated endocytosis, host DNA insertion, virion assembly then budding.
How do retroviruses infect?
Integrate into genem and produced cDNA where viral integrase integrate them into genome
What are examples of transformation viruses?
Retrovirus
Human papillomavirus
How does Human Papillomavirus infect?
Contain oncogenes within own genome, integration leading to host cell machinery expression
HPV
This carries oncogene E6 which inhibits P53 function
What is lysis infection?
This is infection of a host with dealth, being pathogenic, like ebola
How does Ebola infiltrate?
Containing glycoproteins binding Niemann-Pick C1 receptors with endocytic internalisation and endosomal transportations
What is the intracellular life-cycle of Ebola?
RNA injectied into cytoplasm by glycoprotein fusion, replicated by viral polymerase enzymes
What is persistent infection?
This is slow-killing of cell, with slow virus release like HIV
How does HIV enter the cell?
CCR5 co-receptor aand CD4 receptor with transcriptase DNA for host integration
How do HIV evade host immune response?
Dormancy of viral genome for persistence.
How does HIV remain dormant?
Inhibition of host cell transcription by binding TF like P53 and NF-kB like NEF protein.
How is HIV latency maintained?
Epigenetic modifications of viral promoter as well as repression of chromatin remodelling complexes that bind the HIV LTR region
LTR region
This is a cis-acting regulatory element that controls the initiation and regulation of HIV transcription.
What does prolonged HIV infection result in?
Replication in T Cells depleting their efficiency with progressive immune dysfunction
Viral Integrase Enzyme
This catalyses viral DNA integration into the host for dsDNA incorporation into host genome forming provirus
Provirus
This is the viral genetic material able to replicate, incorporated into the host genome
How is latency reactivation stimulated?
Environemtnal signals where peristence triggers immune response with antibody production and immune cell activation
What is latent finfection?
Virus is present but not harmful until stimulated, like Herpesvirus
What are the steps of the Virus life cycle?
Attachment
Uncoating
Replication
Biosynthesis
Assembly of virus
Budding
How does attachment occur?
Outer envelope surrounding the genome has proteins binding host cells, or membrane fusion
What is the process of uncoating?
Release of nucleic acids with fusion of envelope with the host membrane like measles
How can uncoating occur?
Endosomal acidification for enveloped viruses or proteolytic cleavage of capsid for naked viruses
What does replication require?
Formation of dsDNA from the viral genome then transport into nucleus with integrase incorporation.
How does integrase faciltiate its function?
Binds long terminal repeats of virus and Barrier-To-Autointegration Factor of host
How does biosynthesis occur?
Binding of RNAP to promoters of the virus with epigenetic modifications
What are the THREE CATEGORIES of viral infection?
Entry - Attachement, uncoating
Replication - Biosynthesis
Exit - Assembly and budding
