B AND T Flashcards
B cells
End of infection B goes to Memory B
Long life
Ready mode - to attack
Make antibodies
First cycle - 15 days to make ABs
Second cycle reduced to 5 days (MemB), 100x more ABs
Faster AB production, faster destruction
Vaccines
Prepare MEM B and T against specific viruses or bacteria
MEM T prevents severe+ - they remembered the virus
MEM T stimulate B response to produce specific ABs
Boosters help when IS cannot produce the required response
Quicker nAB dropoff
ANTIBODIES
Diminish with time post infection/vaccination
New ones created A/R
Initial nABs help prevent infection but is not sole indicator of vaccine effectiveness
T cells
T recognises virus
T signals B to produce specific ABs
Immunological memory
ABs
MEM B
MEM CD8+ T
MEM CD4+ T
Not all about ABs
New subject
Paper forwarded by Chise
https://www.science.org/doi/10.1126/sciimmunol.abl4509#.YTFPFaWpCph.twitter
Prof Akiko Iwasaki
Excited to share our work by @BenIsraelow et al published today.
We asked what are the roles of antibodies vs. T cells in controlling:
- primary infection,
- reinfection, and
- vaccine-mediated protection?
First, we asked if B cells are needed to control primary infection?
We used muMT mice (devoid of B cells) transduced with AAV-hACE2.
These mice had only a slight delay in viral clearance.
Thus B cells are not necessary for controlling primary SARS-CoV-2 infection.
However, in mice that have neither T cells nor B cells (RAG-/-), SARS-CoV-2 persisted with no sign of clearance.
Thus, innate immunity is insufficient,
Adaptive immunity is required to control primary infection.
These findings have important implications in the persistent SARS-CoV-2 infection we see in immunocompromised patients
This implies that defects in T and B cell immunity predispose people for chronic COVID infection.
Next, we wanted to know if CD4 vs. CD8 T cells are required for clearance of primary SARS-CoV-2 infection.
Depletion of CD4 or CD8 had moderate effects on loss of viral control.
However, depletion of both CD4 and CD8 T cells resulted enhanced viral replication.
What is the role of CD4 T cells in primary SARS-CoV-2 clearance?
It turns out that the role of CD4 T cells is mainly to support antibody production
Because in the absence of B cells, CD4 T depletion had little impact on viral control
Are T cells or Ab sufficient to control primary infection with SARS-CoV-2?
@BenIsraelow collected either sera (Ab) or T cells from infected mice at 14 days, and transfer to RAG-/- host, which were challenged with virus.
Turns out that Ab > T cells in controlling virus.
Next, we asked whether mRNA vax or natural SARS-CoV-2 infection establishes lung-resident CD8 T cells.
While both induced comparable circulating CD8 T cells (IV+), natural infection»_space; vax in establishing tissue-resident CD8 T cells (IV-). #mucosalimmunity
How well does the mRNA vax or primary infection protect against VOC, and how much of that depends on CD8 T cells?
Great news is that the mRNA vax or prior infection protected 100% of mice, even after CD8 T depletion at the time of challenge.
