Immunology of Covid-19 Flashcards
In the corona-virus, where does the name corona come from?
- spike proteins present on cell surface resemble a crown
- latin for crown is corona
What type of genome is Covid-19?
1 - +ssRNA
2- +ssDNA
3 - -dsRNA
4 - +dsDNA
ss = single stranded ds = double stranded
1 - ssRNA
Is Covid-19 an enveloped or non-enveloped virus?
- enveloped
- protects viral DNA/RNA, helps virus evade immunity and facilitates cell entry for the virus
What is the main function of the spike protein located on the Covid-19 virus?
1 - inhibits binding to host cell membranes
2 - binds to host cell membranes
3 - evades immunity
4 - kills T and B cells
2 - binds to host cell membranes
Covid-19 is described as zoonotic. What does zoonotic mean?
- virus came from animals (bats here)
- think zoo and think animals
The S or spike protein located on the corona virus has been linked with what enzyme, and the associated symptoms of Covid-19?
1 - angiotensin-converting enzyme 2
2 - creatine kinase
3 - lactate dehydrogenase
4 - gluconeogenesterase
1 - angiotensin-converting enzyme 2
Covid-19 is a +ssRNA. What does the positive relate to?
1 - signifies virus is inside the cell
2 - identifies that the RNA is actually mRNA
3 - signifies the virus has not infected the host
4 - identifies that the RNA needs to be processed before entering the host DNA
ss = single stranded
2 - identifies that the RNA is actually mRNA
- this is important as it can be copied immediately by the ribosome in the cell
- important for infection so proteins can be produced
Covid-19 contains a nucleocapsid (N) protein. In addition to being a structural protein, what other functions does it have?
1 - helps bind to cell membranes and manipulate cell cycle
2 - helps infect cells and manipulate cell cycle
3 - assembly, transcription of proteins and manipulate cell cycle
4 - kills T and B cells and manipulate cell cycle
3 - assembly, transcription of proteins and manipulate cell cycle
In Covid-19 there are 2 large regions of the ssRNA that are called 1a and 1b, relating to non-structural proteins. There are a large number of these non-structural proteins. What is the function of non-structural proteins-1 (NSP-1)?
1 - interact with cell membranes allowing spike protein to bind
2 - Interacts with ribosomal mRNA-binding channel+inhibits host protein translation
3 - interfere with host immune response
4 - accentuates translation of viral mRNA and helps evade immune system
2 - Interacts with ribosomal mRNA-binding channel+inhibits host protein translation
- if cell is not making its own proteins it can make viral proteins
In Covid-19 there are 2 large regions of the ssRNA that are called 1a and 1b, relating to non-structural proteins. There are a large number of these non-structural proteins. What is the function of non-structural proteins-15 (NSP-15)?
1 - interact with cell membranes allowing spike protein to bind
2 - Interacts with ribosomal mRNA-binding channel+inhibits host protein translation
3 - interfere with host immune response
4 - accentuates translation of viral mRNA and helps evade immune system
3 - interfere with host immune response
- senses of the innate immune system are inhibited specifically interferon
In Covid-19 there are 2 large regions of the ssRNA that are called 1a and 1b, relating to non-structural proteins. There are a large number of these non-structural proteins. What is the function of non-structural proteins-16 (NSP-16)?
1 - interact with cell membranes allowing spike protein to bind
2 - Interacts with ribosomal mRNA-binding channel+inhibits host protein translation
3 - interfere with host immune response
4 - accentuates translation of viral mRNA and helps evade immune system
4 - accentuates translation of viral mRNA and helps evade immune system
- essentially makes MHC-I look less like an infected cell
Covid-19 contains a nucleocapsid (N) protein. In addition to being a structural protein it is also involved in assembly, transcription of proteins and can manipulate the cell cycle. The N protein has also been described as a Viroporins. Viroporins are small virally encoded hydrophobic proteins that oligomerize in the membrane of host cells, loosening of tight junctions and leading to the formation of hydrophilic pores. Why is this important in Covid-19?
- damages the epithelial membranes throughout the body
- means the virus can easily spread
The Covid-19 virus has 2 domains, which are areas of a protein that have a unique function, which is where the name S1 and S2 of the spike protein come from. This is important as this is how Covid-19 has been shown to bind with and infect the host. Is it the S1 or S2 domain that is involved in the interactions with angiotensin converting enzymes-2?
- S1
- protein must be in the up conformation for this to work
The Covid-19 virus has 2 domains, which are areas of a protein that have a unique function, which is where the name S1 and S2 of the spike protein come from. This is important as this is how Covid-19 has been shown to bind with and infect the host. Is it the S1 or S2 domain that is involved in the interactions with host cells leading to infection?
- S2
There are specific parts of the spike 1 protein that facilitate binding to ACE2 in the up confirmation. Using the labels below, label the parts of the spike 1 protein:
- receptor binding motif
- human ACE2
- receptor binding domain
1 - human ACE2
2 - receptor binding motif
3 - receptor binding domain
What is glycan shielding in terms of Covid-19?
1 - gylcans bind immune cells and render them inactive
2 - glycans replace the antigen altogether
3 - glycans are added to virus to hide antigens
4 - glycans release cytokines that are anti-inflammatory
3 - glycans are added to virus to hide antigens
- if no antigens are visible the immune cells cannot target the cell
Anti-genetic drift is the accumulation of random or stimulated mutations over time due to selective pressures for survival, specifically to regions where antibodies would bind. In terms of Covid-19 virus, where would there be the location for mutations to occur?
1 - N protein
2 - M protein
3 - S protein
4 - Envelope protein
3 - S protein (specifically the S1 domain)
- constant mutations ensure antibodies cannot effectively bind
- ensure the virus is very difficult to kill
What is immune imprinting?
1 - body produces a new antibody and then replicates it to fight a virus
2 - previous exposure to a virus is used to fight a new virus as it resembles old virus
3 - effector cells are replicated to fight the virus
4 - immune cells form a barrier around virus so it cannot infect host cells
2 - previous exposure to a virus is used to fight a new virus as it resembles old virus
- essentially old antibodies will be used, despite potential mutations
Immune imprinting is when the body uses previous exposure to a virus to fight another virus that may resemble the original virus, essentially old antibodies will be used, despite potential mutations. Why is this bad in Covid-19?
- variations of the virus like Omicron have mutated S proteins
- old antibodies are not as effective
- BUT B cells may not undergo clonal expansion and create new plasma cells
Glycan shielding is where the virus adds glycans to its structure to hide the S1 domain of the spike protein from antibodies and thus hide the antigens. If no antigens are visible the immune cells cannot target the cell. What can host immune system do to try and tackle this problem?
1 - produce pentraxins (CRP) to bind with glycans
2 - produce ficolins to bind with the glycans
3 - produce mannose binding leptin protein (MBL-P)
4 - produce T cells able to bind sugars
3 - produce mannose binding leptin protein (MBL-P)
- the sugar mannose is present on the glycans on the S1 domain
- MBL-P can bind and active the complement system
- produce membrane attack complex, opsonisation and agglutination
There are specific parts of the spike 1 protein that facilitate binding to ACE2 in the up confirmation. The 3 parts of the spike 1 protein are
- receptor binding motif
- human ACE2
- receptor binding domain
Which part of this structure do antibodies target?
- receptor binding domain
