a bonobo humanity?

One way – maybe not a good way – of learning about the immunological system is being alerted to something – a term or an acronym, and going down its rabbit hole to find its connection to things you know a little about. So, neutralising antibodies and Omicron – I’ve taken this phrase from an early episode of The Immunology Podcast  (ep 24 – though that wasn’t the main topic of the episode, linked below), Omicron being a late and seemingly less deadly variant of SARS-CoV-2, – what to make of it?

A neutralizing antibody (NAb) is an antibody that is responsible for defending cells from pathogens, which are organisms that cause disease. They are produced naturally by the body as part of its immune response, and their production is triggered by both infections and vaccinations against infections.

Which makes me wonder – aren’t all antibodies neutralising antibodies? Well, there are also binding antibodies, which bind to a pathogen and alert the immune system to its presence so that it can then be destroyed by white blood cells. Neutralising antibodies are a product of B-cells in the bone marrow. They work ‘by affecting how the molecules on the pathogen’s surface can enter cells in the body’. For example, with viruses there are two types, enveloped (they’re inside a lipid membrane) and non-enveloped.  The enveloped types are heat-sensitive, the non-enveloped are heat resistant, which sort of makes sense. In the case of the enveloped type, the neutralising antibody blocks its attachment to and entry to the cell, and with the non-enveloped type, the antibody can bind to the capsid protein, which is the protein shell that surrounds the genetic information within a virus cell.

So where do we go from here? Well let’s look at this capsid protein and how the antibody binds to it, presumably to prevent the virus from replicating – what they mean by neutralising? But take this:

Neutralizing antibodies can also stop pathogens from changing their structure and shape, known as conformational changes, in order to enter and replicate within a cell.

So pathogens can change structure and shape once they’re in the body, in order to enter into particular cells within that body? Anyway, there are viruses that can get their way around NAbs by means of regular mutation. Such viruses include Zika and dengue, not to mention influenza. And it can get worse:

A process known as antibody-dependent enhancement (ADE), which leads to more severe infections, can take place when a virus binds to antibodies that help the virus infect cells. The virus is better able to enter into cells in the body and is sometimes more able to replicate once it has entered a host cell.

So it seems these antibodies are a double-edged sword, as these summarising remarks indicate:

Neutralizing antibodies have found application in medicine and are often used as part of vaccines, but they have been found to help viruses enter cells and replicate to cause severe infections, and as such ensuring that neutralizing antibodies will not facilitate infection is an important part of developing vaccines.

So that’s enough of NAbs for now….oh but what about that connection with Omicron?  Omicron was/is a highly mutated variant of SARS-CoV-2 which has ‘evolved into many different sub-variants’ according to the abstract of the paper linked below, which lists at least some of these sub-variants, and it’s a long list. It seems these sub-variants may have survived/thrived by being a whole lot less lethal than the original strains. But don’t take my word for it. Anyway the paper was published back in March 2023, and the pandemic was very much on the wane by then I think, so it does seem as if the virus has found an accommodation with our bodies, or antibodies, or whatever.

So enough already, I think it’s time to switch to another topic, I’m way out of my depth with this one. And yet, it’s so…. I’ll keep listening to the podcast, at least.

References

https://www.news-medical.net/health/What-are-Neutralizing-Antibodies.aspx#:~:text=A%20neutralizing%20antibody%20(NAb)%20is,infections%20and%20vaccinations%20against%20infections.

https://pmc.ncbi.nlm.nih.gov/articles/PMC9985919/

https://www.science.org/doi/10.1126/scitranslmed.abn8057

Ep. 24: “Autoimmune Disease” Featuring Dr. Jennifer Gommerman