Hello,
I am reading on vaccines in general and I wonder if the beneficial effects of vaccines (as vaccination is the most effective choice when pathogens are to be stopped and prevented) lower the Darwinian fitness of immune cells such as T-cells and B-cells.
Thank you for your answers!
Generally spoken: no. The fitness of the immune system can more or less be regarded as infinite. What does happen is that vaccines trigger specific subsets of immune cells that differ from those getting activated by a natural infection. This can either be benificial, or not.
I'm not sure if they can lower the fitness of immune cells, maybe yes, but for sure they lower the fitness of the whole organism.
In a natural infection, innate immunity plays an important role in activating adaptive immunity but also in responding to the pathogen itself. It takes around 1 week to mount an appropriate adaptive response, so in the meanwhile the protection is on innate immunity, if it doesn't work properly the pathogen may spread and the organism can die. So probably, vaccines affect more the fitness of innate immune system than the adaptive one.
Also, infectious diseases can have delayed effects. Not all the infected individuals experience these effects, meaning that probably some individuals are more prone to them, so having a lower fitness. Vaccines abrogate these differences
For "naturall" immunity, the pathogens we encounter are well-dealt with.
"Novel" pathogens must be dealt with harshly ,in any way possible, until the immune system catches up. If the viruses are made of specific capsids and antigens, they can be problematic for individual populations.
Hence, the "quadranto girjono" - forty days before ships could enter Venice.
Biblical - no?
Costanza Maria Cristiani I agree with you, vaccines stimule via Il4 B lymphocytes and favorise Th2 pathway. Th2 who give a decline of Th1 necessary to destrue cancer and viral infections
I'm not sure what do you mean by the Darwinian fitness regarding lymphocytes.
Lymphocytes are antigen specific cells which can respond to the exact particular antigen (or extremely close related) and naive, antigen non-experienced cells are very unique (usually each lymphocyte clone is available in almost single quantity around the whole body) and it takes much time find, activate and expand them in order to mediate protection. Quite often a particular pathogen may successfully evade eradication and expand alot. So it's eradication also requires efforts from the organism.
Without antigen activation naive lymphocytes are useless (the body carries plenty of the cells which will never even meet their antigen, but it's required to have an array of potential antigen responders).
So, during vaccination we selectively expand these useful antigen-specific cells and differentiate them towards memory cells. So, when the infection happens the pathogen will be met not with a few naive cells which require deployment, but with a pool of differentiated and ready to act T-cells and antibodies produced by the respective B-cells. And if the pathogen doesn't come, then at least lymphocytes will differentiate towards long living memory cells.
So, upon vaccination lymphocyte clones expand and become more fit and grant protection against the respective pathogen.
I guess, that is profit and increased Darwinian fitness.
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