# RKS: NOVEL CORONAVIRUS 2 - Insight Into The 'Ultimate' Kill Strategy By Body's Defenses

 

# RKS: NOVEL CORONAVIRUS 2 - 

Insight Into The 'Ultimate' Kill Strategy By Body's Defenses

1st July 2021

THE VACCINE - BODY DEFENSES INTERFACE

Dear Reader,

Never before in known history of mankind has there been a vaccine available sans stringent testing. And never before has the World Health Organization (WHO) ever exercised its emergency validation veto for a vaccine until the fast-tracked approval granted for the COVID-19 vaccine!

What is the role of vaccine? Vaccines contain an inactivated / suppressed virus or bacteria (hereafter referred to as pathogen - meaning either virus or bacteria) or its inactive parts which when injected stimulates the body's responses. Hence, the vaccine substance is the antigen and to fight antigens the body must make specific antibodies.

SEQUENCE OF EVENTS IN KILLING OF AN INVADER & DISPOSING OF ITS REMAINS

1. The pathogen first infects a single cell of human (meaning the host). Once it penetrates into the host cell the virus or bacterium now becomes invisible.

2. The infected host cell makes an antiviral chemical called interferon (IFN) in an effort to limit the spread of the pathogen. This is achieved in 2 ways:

a) The IFN can directly kill the virus that has invaded.

b) The IFN also attracts Natural Killer (NK) variety of T cells to assist in disposing of the pathogen.

3. There are white blood cells (WBCs) swarming in the blood and every ready to fight pathogens, antigens and allergens. Those important for tackling infections include lymphocytes and neutrophils. Lymphocytes constitute 20-40% of WBCs and have a role to play in identifying, fighting, killing and disposing off the invading pathogen. The important types of lymphocytes for the said purpose include: T cells (80%) and B cells.

a) NK (T) cells (5-15% of T cells): These blood cells are the first to react and help kill the pathogen by secreting IFN and also by another destructive chemical called Tumor Necrosis Factor (TNF)- alpha. NK cells are always supercharged and can act fast and prompt to reflexly kill any invader.

b) Cytotoxic T cells (10-30% of T cells): These blood cells require activation and then enter the battle arena later to dispose of the virus or bacteria.

c) B cells (20% of lymphocytes): These blood cells are the manufacturers of antibodies - also medically known as immunoglobulins (Ig).

4. The NK cells are always on the prowl searching for an infection.

a) The surface of every host cell has a MHC I (Major Histocompatibility Complex class I) protein molecule. When the virus attacks it hijacks the protein manufacturing machinery of host cell in order to make its own proteins. Thereafter pieces of peptide proteins made by virus get displayed by the MHC class I on the host cell surface. This enables the roaming NK cells to identify which host cells have been invaded by the virus!

b) In the first 1-2 days, following pathogen invasion, the NK cells cannot identify a specific virus or bacterium and attacks the invader as if blind-folded. 

c) The fight afforded by IFN from host cell and NK cells, as well as TNF-alpha liberated by latter, buys time for the body to reinforce with the pathogen-specific defences.

4. In 3-4 days pathogen-specific Cytotoxic T cells are activated and these multiply so as to mount a full-blown attack on the virus. The Cytotoxic T cells annihilate the virus or bacterium by following sequential mechanisms with the help of protein-based chemicals.

a) Perforin: This drills a hole in the infected host cell.

b) Ganzymes: These are enzymes that enter via the created pores to kill the pathogen and thereafter program the death of the infected cell (process called apoptosis).

c) Granulysin: A toxic factor which dissolves the cell to ultimately remove the infected host cell. 

If the invaded virus has not divided (replicated) the T cell - mediated killing is enough to tackle the infection. However, if the virus has replicated inside the host cell it enters the blood.

ROLE OF ANTIBODIES IN PATHOGEN KILLING

The pathogen that has entered the blood is called - as the famously now known word 'antigen'. It is now the turn of B cells to eliminate the pathogen. B cells have a receptor on their surface called B-cell receptor (BCR) which is nothing but a Y-shaped Ig. 

1. When antigens bind to BCR, B cells are differentiated into plasma cells.

2. Plasma B cells produce a specific single type antibody to counter the specific antigen. These antibodies are secreted into the blood and other parts of body.

It is the Ig that ultimately confronts and help eliminate the virus.

THE ANTIBODIES ENIGMA

For fighting infection due to bacteria and viruses the body has 3 types of antibodies:

1. IgA: These comprise 15% of total Ig and protect the linings of the intestine and airway passages.

2. IgM: These comprise 10-15% of total Ig and constitute the body's first INITIAL response when attacked by a virus or bacteria (antigens).

3. IgG: These comprise 70-80% of total Ig and are specific antibodies present to fight against specific antigen. IgG is responsible for the long-term immunity against pathogens.

Ig can eradicate the infective bacteria and viruses by 4 mechanisms:

1. Neutralize the virus / bacteria: Ig block the binding sites of the pathogen so it cannot access and penetrate the host cell.

2. Agglutination: Ig make the pathogens such as virus stick to each other (agglutination) and enable clumping. The NK cell and neutrophils (collectively known as phagocytes) can easily identify and destroy the agglutinated virus in comparison to a single virus.

3. Phagocytosis: The Ig bound virus has special binding affinity for Fc receptors present on the WBCs. Thus the phagocytes swallow the antigen-bound virus and then destroy it with the help of free radicals and destructive enzymes secreted within the cell.

4. Complement system activation: When Ig activates 'complement system', another defence mechanism of the body, the virus is made more weaker and becomes easily susceptible to killing via phagocytosis.

The ability of antibodies to neutralize the virus and bacterium is a major protective benefit afforded by vaccines. 

VACCINES AND PROTECTION AGAINST SARS-CoV-2 

The SARS-CoV-2 [also called novel coronavirus-2 (nCoV-2)] can be dealt with by the body by a 2-pronged defence:

1. If the virus attacks the host cell and has not yet multiplied: The NK cells can kill the virus and limit spread and the infection process.

2. If the virus attacks the host cell and has multiplied: The antibodies need to tackle the virus so as to curb the infection.

Symptoms in COVID-19 occur because the immune mechanisms fight the viral army and not the single virus that has already entered inside the host cell and become undetected. Thus, it requires the SARS-CoV-2 to be eliminated by the Ig since the virus battalion has already multiplied and entered the blood.

The prime role of vaccines, therefore, is to strengthen the immune system by assisting in developing specific antibodies for the SARS-CoV-2 in our fight against the menace of COVID-19. 

DISCUSSION

All the basic discussed above is pure science and based on published and well known facts about immunity and immune mechanisms. Unless the same is grasped all the debates that one has regarding the current vaccination and its controversies is mere one's perception and individual understanding and could be baseless in the context of medical science and its realities. 

Which vaccine? When vaccine? Vaccine interval? With changing stances by the manufacturers,  regulators (including Indian Council of Medical Research - ICMR) and even WHO the present scenario is confusing. Why? Because the nCoV-2 is novel as its name states, and the vaccines have not been afforded breathing space to ascertain their optimal capabilities (& limitations). So the bottom line is:

1. If you want to be vaccinated check your antibodies prior.

2. Re-check antibodies concentrations post-vaccination to ascertain its benefit to each one as an individual.

3. Post-COVID-19 infection, if one has been unlucky, need to ascertain the amounts of antibodies lingering before deciding upon further course of action regarding immunization.

If antibody levels are extremely high, even more than following vaccination, taking a dose of vaccine is like driving expertly on a road trip from Kanyakumari to Kashmir and then undergoing a driving test, as one of my dear doctor colleague had once professed!

One needs to be a well-informed consumer of vaccine if the benefits are to be maximised!

DR R K SANGHAVI

Prophesied Enabler

Experience & Expertise: Clinician & Healthcare Industry Adviser