Covid 19 (Sars Cov 2) Flashcards
Structure Covid-19
Large
enveloped
pleomorphic
Genetic material
ssRNA (+ve)
Surface antigen covid 19
Spike glycoprotein (required for entry)
Proteins covid 19
Spike glycoprotein
Membrane protein
Envelope protein
(lipid bilayer)
Development of SARS
Sars Cov 1
Mers
Sars Cov 2
Sars Cov 1&2 bind to
ACE2 protein
Mers binds to
DDP4
Sars Cov 1
Asia 2002
Bats –> civets –> humans
MERS
Middle east 2012
Bats –> camels –> humans
Sars Cov 2
Wuhan, China 2019
Bats via unknown
All Coronaviruses came from…
BATS
Transmission Covid
Airborne (suspended, remain for a while)
droplets (coughs and sneezes create droplets of saliva and mucus)
Droplet vs airborne sizes
Droplets >5 microns
Airborne <5 microns
Barriers to Coronavirus
Mucus traps virus particles
Ciliated respiratory epithelium
Lungs: IgA, natural killer and macrophages
How does virus enter cells?
Spike protein binds to ACE2 membrane (lungs, GI, heart and kidneys)
Receptor mediated endocytosis (cell envaginates around virus)
How does coronavirus replicate?
ssRNA +ve –> ssRNA -ve –> ssRNA +ve
(RNA dependent RNA polymerase)
ssRNA +ve + viral proteins = nucleocapsid
(viral proteins come from ssRNA +ve)
Enzyme involved in coronavirus replication
RNA dependent RNA polymerase (RdRp)
Incubation period omicron
3 days
Top 5 symptoms of omicron
Runny nose Headache Fatigue Sneezing Sore throat
Diagnosis of COVID 19 methods
RT-qPCR
Lateral flow test
RT-qPCR stands for…
Reverse transcriptase quantitative PCR
Nasopharyngeal swap
Method of RT-qPCR
Swab
Extract RNA and convert to DNA
Amplify via PCR with SARS-COV2 primers
Viral RNA presence = active infection
Requirements to convert covid RNA to DNA and amplify
Reverse transcriptase Sequence specific primers DNA polymerase dNTP (deoxyribonucleotide triphosphate) mRNA
Lateral flow explained
Antibodies on lateral flow
Antigens on virus bind to antibodies
Antibodies dragged up test line by antigens
Antibodies bind to 2nd antibody to give visual result
LFT vs PCR
LFT less sensitive but very specific (antibody are specific)
LFT shows +ve when infectious (tests for surface proteins)
PCR tests for genetic material - can remain for weeks/months after
Why do we get variants of coronavirus?
Constantly replicating (10 hour life cycle) RNA polymerase: high error rate and lack of proofreading = mutations (genetic variation/resistance)
Different covid variants
Alpha (May, UK) Beta (August, south africa) Gamma (November, Brazil) Delta (October, India) Omicron (November, everywhere)
Early variants
Spread more easily
Vaccines less effective (B-D)
BUT effective protection against severe disease
Different vaccines
Viral vector
RNA
Whole virus
Protein subunit
Viral vector vaccine
Harmless virus used
Alter virus to contain some COVID genetic code
(Oxford/Astrazeneca)
RNA vaccine
Synthetic version of COVID 19 genetic code (mRNA)
Pfizer/Moderna
Whole virus vaccine
Weakened/inactive virus
CoronaVac
Protein subunit vaccine
Pieces of Covid 19 virus
eg spike protein fragments
(Novavax)
What do whole virus/protein subunit vaccines create?
Immune response
What do viral vector/RNA vaccines create?
Genetic code tells our cells to make spike protein which then triggers immune response
