Viruses And Helminths Of The Nervous System Flashcards
What is the importance of studying viral diseases
Viruses infect various parts of the nervous system
Why is the Polio virus still around
Almost eradicated by the world
Misinformation- people dont take vaccines,
Outline the structure of viruses
Nuclei acid- store genomic information
Capsid- protein rich capsule, made up of small proteins called capsomeres
Nucleocapsid- nuclei acid and capsid
Viral proteins
Lipid envelope- phospholipid bilayer
Enzymes
What are the two major structures of viruses
Enveloped viruses
Naked viruses- no lipid envelope
Outline viral biodiversity
-morphology (size and shape)
-type of nuclei acid in the genome
-how they produce mRNA
Outline the steps of viral replication
-Attachment
-Penetration
-Uncoating and synthesis
-Assembly and release of viruses
Outline the attachment step in viral replication
Determine severity of infection, what host the virus attacks and where it occurs
Outline the penetration step in viral replication
Viruses can penetrate the host cell by either fusing with the host cell membrane or by priming the host signalling pathway leading to endocytosis.
What is a spike protein
Very specific viral protein
What is fusion in viral replication
How a virus enters cells
Endocytosis
Outline the un coating and synthesis step in viral replication
The shell of the capsid disintegrates and the HIV protein (reverse transcriptase) transcribes RNA into DNA
HIV specific- Viral DNA is transported across the nucleus and takes its genome and integrates it into hosts DNA
What are the mechanisms of virus entry into host cell
Endocytosis:
-macropinocytosis
-clathrate mediated
-caveolae
-lipid raft
Fusion
Outline the assembly and release of viruses step in viral replication
Some of the replicated RNA becomes the genome of new viruses, while the cell uses other copies of the RNA to make new HIV proteins. The new viral RNA and HIV proteins move to the surface of the cell, where a new, immature HIV forms.
The virus is released from the cell, and the HIV protein (protease) cleaves newly synthesised poly proteins to create a mature infectious virus
What is classification
The arrangement of organism into taxonomic groups according to their observed similarities
(Classical Linnaean hierarchy system)
What are the current classification systems
ICTV (international committee on the taxonomy of viruses)
-still based on classical Linnaean heiarchal system but primarily depends on the genome and nuclei acid material of the viruses
What is the Baltimore classification system.
All viruses want get to a protein stage
7 classes of viruses
What are class 1 viruses
Double stranded DNA viruses (herpes)
Transcribe DNA to form mRNA
What are class 2 viruses
Single stranded DNA viruses
Hold genomic material as DNA, either in positive or negative sense
Convert into double stranded DNA- transcribed to mRNA
What are class 3 viruses
Segmented genomes. Each genome segment is transcribed separately to produce monocistronic mRNA
What are class 4 viruses
Single stranded RNA, positive sense (polycistronic mRNA)
Convert mRNA into RNA in negative sense to make more of RNA in the positive sense
What are class 5 viruses
Influence, ebbbola
Hold genomic material as RNA in negative sense
Make mRNA by converting negative RNA to positive RNA
What are class 6 viruses
HIV
Hold DNA as single stranded RNA in positive sense, diploid- two at a time
DNA/RNA hybrid using reverse transcriptase
RNA disintegrates, DNA is replicated
Outline the antigenic drift regarding viral mutations
Viruses accrue small mutations as they spread and replicate
Two viruses combine to form a new virus- reassortment
What is neurocysticercosis
The infection caused by the larval form of the tapeworm ‘taenia solium’ the most common parasitic disease of the CNS and the most common cause of acquired epilepsy worldwide
This has primarily been a disease that remains endemic in low-socioeconomic countries, but because of increased migration neurocysticerosis is being diagnosed more frequently in high-income countries
