Neutralizing Antibodies: What We Should Know.
Updated: Aug 23, 2021
When we started fighting Covid 19, we had experts searching for effective solutions for a pandemic. They concurred that there were several possible ways the pandemic might unfold. Speculations ran high, and studies hinted at early detection, trace, and control as the most efficient way for control while conspiracy theorists were branching out wildly, even virulent than the virus itself.
One of the most heard stories during this pandemic are those about neutralizing antibodies (NAbs), how they stop infections by incapacitating the invading pathogen, and the breakthrough role they play for possible future treatments and better diagnostics.
More than just a story, the vital role that neutralizing antibodies play in our war against Covid-19 is real. Neutralizing antibodies can be measured semi-quantitatively to investigate the correlation of their levels in post-infection/recovery and/or post-vaccination with protection.
Vaccines have been rolled out and we only have the experts to thank for having been inoculated with the proper protection against Covid 19. While all the conspiracy theories die down, including the alleged hidden microchip and the utterly ridiculous 2-year post-vaccine zombie effect, we come to terms with what is real and what is not.
In retrospect, the world was ravaged the same way in 1918 with millions of lives lost worldwide. There was no prior course of action other than the lives we lost on that recorded milestone in world history. Over the last few months within this pandemic, medical and scientific experts have come up with their best efforts, and alas, we have developed vaccines over a record period of time.
But what do we really know about NAbs?
Admit it or not, we tend to lose ourselves in the translation of all the medical and scientific jargon. But on the flip side, and as all our healthcare and medical professionals try hard as they possibly can, there isn’t any other way to herald everything Covid 19 related to the masses.
It just isn’t possible, and yet here you have another spin on the subject.
To narrow down the complexities of medical jargon and whatnot here are a few words to explain the how’s and why’s of neutralizing antibodies. There will be medical terms you will encounter, few and far between in getting to the bottom line, but worry not. We’ll see through the journey together.
Antibodies explained.
Antibodies have three main functions:
Antibodies are secreted into the blood and mucosa, where they bind to and inactivate foreign substances such as pathogens and toxins (neutralization).
Antibodies activate the complement system to destroy bacterial cells by lysis (punching holes in the cell wall).
Antibodies facilitate phagocytosis of foreign substances by phagocytic cells (opsonization).
Antibodies have roles to play in the four key features of the immune system, which are;
Specificity: Antibodies precisely recognize toxins and pathogens.
Diversity: Antibodies against a variety of antigens preexist in the body.
Immunological memory: Reinfection doesn’t redevelop symptoms.
Immune tolerance: Self cells and tissues are not normally attacked.
Adding to the 3 main functions of antibodies and the four key features of the immune system, our bodies have the innate ability to produce five types of antibodies, these are the following;
IgA
IgD
IgE
IgG
IgM.
Ig stands for immunoglobulin and the five antibodies each have a job to perform when infection strikes, they protect the body from getting sick. Among the five, we fix ourselves on Igg and IgM. These two main antibodies are our main focus in pursuit of understanding antibodies and Covid 19. The IgM antibodies are the first ones to be produced. These are produced about a week into the infection and their levels peak at about three weeks into the infection. This system acts rapidly but it's not great at eliminating a pathogen for long periods of time. It only does so in the early stages.
IgM antibodies offer temporary protection as the body ramps up its production of the Igg
antibodies. The IgG antibodies provide the bulk of protection and also make about 75 percent of all antibodies in our system, they neutralize toxins and bind to the pathogen. They are long-lived and they decline very slowly. Once produced they can be produced again quickly the next time a person is exposed to the same pathogen.
Neutralizing antibodies and binding antibodies, what’s the difference?
Not all antibodies that bind a pathogenic particle are neutralizing. Non-neutralizing antibodies, or binding antibodies, bind specifically to the pathogen but do not interfere with their infectivity. That might be because they do not bind to the right region.
Non-neutralizing antibodies can be important to flag the particle for immune cells, signaling that it has been targeted, after which the particle is processed and consequently destroyed by recruited immune cells. Neutralizing antibodies on the other hand can neutralize the biological effects of the antigen without a need for immune cells. In some cases, non-neutralizing antibodies or insufficient amounts of neutralizing antibodies binding to virus particles can be utilized by some virus species to facilitate uptake into their host cells. NAbs from SARS-CoV-2 usually form approximately 1-2 weeks following infection.
In essence, NAbs are;
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.
Neutralizing antibodies can result in lifelong immunity to certain infections and can be used to see if a person has developed immunity to an infection after they have recovered from it.
Neutralizing antibodies can be confused with binding antibodies, which are responsible for binding to a pathogen and alerting the immune system to its presence so white blood cells can be sent to destroy it. Neutralizing antibodies, although an integral part of the body’s immune response, serve a different purpose to binding antibodies.
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.
In bacterial infections, neutralizing antibodies can block the harmful effects of toxins. This has been shown to happen in diphtheria medications, although they are no longer recommended to prevent diphtheria infections. Once a pathogen has been neutralized by a NAb, the pathogen is degraded by white blood cells, and the spleen filters the pathogen for it to then be excreted through urine or feces.
A common use for neutralizing antibodies in medicine is passive immunization. This is the process in which a person who is not immune to disease is given antibodies from a person who is already immune to the disease. Vaccination also makes use of neutralizing antibodies, which is known as active immunization. Vaccines are designed to mimic a natural immune response to an infection by injecting an active specimen of a virus or bacteria or part of a virus or bacteria into the body.
The immune system can be triggered to produce neutralizing antibodies in response to the virus or bacteria in the vaccine, which will then recognize and fight the infection naturally if the person is exposed to the pathogen for a second time. Serologic tests cannot diagnose acute infections but can expand the time for the testing window beyond the acute infection phase. NAbs are produced by B cells within the immune system and are characterized by stopping infections through incapacitation of the invading pathogen.
Among the various immunoglobulins raised in response to infection, coronavirus NAbs are unique. This is because they block the interaction between ACE2 (the cognate receptor) and the coronavirus spike protein receptor-binding domain. Or, they prevent the transferral of genes to host cells by viruses. The placement of the designated signal cutoff dictates the interpretation of semi-quantitative NAb assays either way.
There are assays used to assist in the tracking of infection chains and can also be used to answer epidemiological, virological, and clinic questions, including, but not limited to, whether a robust antibody response has occurred and how many infected individuals have remained asymptomatic.
There have been instances where antibody testing was used incorrectly. Leaving people with the false assumption that once you're positive for antibodies, that somehow correlates highly to being immune or having resistance. That's not necessarily the case. We need to look at the specific types of antibodies that provide that immunity. Recently, the FDA had approved 50 antibody serology tests and of those only one of them was a neutralizing antibody test.
The truth is the ability to detect neutralizing antibodies, can help us gain additional insight into the fight against this virus, and more importantly, NAbs is going to be an important component of the vaccine. Especially in tracking and knowing when boosters are needed and when we might trail off to a level where our vaccine is no longer effective.
Neutralizing antibodies now play a vital role in post-vaccine applications and overall population immunity tracking. It has been used previously and will continue to be used in research for different studies that are occurring and to date, measuring vaccine efficiency in a quantitative way.