Naked Science Forum
Life Sciences => Cells, Microbes & Viruses => Topic started by: colarris on 18/04/2020 10:12:58
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Can antibodies overcome all antigens?
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Antibodies have limitations.
- In mammals, antibodies are a Y-shaped molecule, with one region that is very variable.
- How much they vary is dependent on how many different options your body has to choose from
- The options are defined by the Major Histocompatibility Complex (MHC)
- Inbreeding reduces the variety of MHC options available to an organism, so the offspring will be less effective at fighting off disease
https://en.wikipedia.org/wiki/Major_histocompatibility_complex
You don't want the immune system to attack an organism's own organs, so the Thymus weeds out immune cells that might attack "self" tissues
- This means that cancerous cells can remain undetected by the immune system because they look like "own" tissues
- This also means that cancers are more likely to get transmitted from one organism to another (eg between Tasmanian Devils) if the population is inbred
See: https://en.wikipedia.org/wiki/Clonally_transmissible_cancer#Other_animals
I understand that sharks have two highly variable regions in their antibodies, so they can generate far more permutations, and match a greater range of potential pathogens than most mammals. (Camel antibodies also seem to be more flexible than other mammals...)
See: https://en.wikipedia.org/wiki/Heavy-chain_antibody#In_cartilaginous_fishes
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Can anti-bodies overcome all antigens?
Yes and no.
Yes, more or less by definition. A thing isn't an antigen unless it causes the body to raise antibodies against it. So, for example, cyanide, while toxic, won't raise antibodies so it's not an antigen.
No, in that an antibody isn't what actually overcomes anything. That's down to the rest of the immune system.
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Thanks for the info. :)
I guess I forgot about HIV(?)
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Camel antibodies also seem to be more flexible than other mammals...
Here is a story published in Cell journal, reporting work done in Llamas (part of the camel family) using Llama antibodies to attack COVID-19.
See: https://thenewdaily.com.au/news/good-news/2020/05/07/llamas-coronavirus-fight-science/
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Rabies viruses escape the immune system by progressing along the nervous system. They are not detected by the Antigen Presenting Cells (macrophages, dendritic cells) that trigger the immune response. But these viruses may be destroyed by antibodies when they are present because of treatment with rabies serum or because they were previously vaccinated.
Antibodies are immunoglobulins. There are different types. Immunoglobulins M (IgM) are predominant during the primary adaptative response of the immune system. They are less effective at neutralizing pathogens than immunoglobulins G (IgG) that characterize the secondary response.
Immunoglobulins A are transmitted by the mother to the fetus or the newborn via the milk.
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Camel antibodies also seem to be more flexible than other mammals...
This week's Naked Scientists podcast did an interview with one of the authors of this paper, generating coronavirus antibodies from a llama.
See: https://www.thenakedscientists.com/articles/interviews/covid-19-antibodies-and-llamas
One comment they made was that llamas were able to produce antibodies against MERS coronavirus, which humans caught from camels (and the camels picked up from bats).
- Since llamas and camels are related, and can both produce these unique antibodies, perhaps the camels could fight off the MERS virus, while their human handlers could not?
- MERs had a much higher fatality rate than COVID-19 (around 35% for MERS vs perhaps 3% for COVID-19)
- but MERS was much less contagious than COVID-19, so MERS didn't turn into a pandemic.
See: https://en.wikipedia.org/wiki/Middle_East_respiratory_syndrome