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Context:

• Bharat Biotech launched its intranasal COVID-19 vaccine iNCOVACC, the first of its kind in India, on January 26.

Read all about Intranasal Vaccines: https://www.iasgyan.in/daily-current-affairs/intranasal-vaccine-11

iNCOVACC^®

• BBV154 – It is novel adenovirus vectored, intranasal vaccine for COVID-19.

Key Attributes:

• An intranasal vaccine stimulates a broad immune response – neutralizing IgG, mucosal IgA, and T cell responses.
• Immune responses at the site of infection (in the nasal mucosa) – essential for blocking both infection and transmission of COVID-19.
• The nasal route has excellent potential for vaccination due to the organized immune systems of the nasal mucosa.
• Non-invasive, Needle-free.
• Ease of administration – does not require trained health care workers.
• Elimination of needle-associated risks (injuries and infections).
• High compliance.
• Scalable manufacturing – able to meet global demand.

Immunoglobulin G (Ig G):

• Immunoglobulin G(Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. 
• IgG molecules are created and released by plasma B cells. Each IgG antibody has two paratopes.
• Function: Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses, bacteria, and fungi, IgG protects the body from infection. IgG are also involved in the regulation of allergic reactions. 

Immunoglobulin A:

• Immunoglobulin Ais an antibody that plays a role in the immune function of mucous membranes.

A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is mostly of endodermal origin and is continuous with the skin at body openings such as the eyes, eyelids, ears, inside the nose, inside the mouth, lips, the genital areas, the urethral opening and the anus. Some mucous membranes secrete mucus, a thick protective fluid. The function of the membrane is to stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated.

• The amount of IgA produced in association with mucosal membranes is greater than all other types of antibody combined.
• In its secretory form, is the main immunoglobulinfound in mucous secretions, including tears, saliva, colostrum, intestinal juice, vaginal fluid and secretions from the prostate and respiratory epithelium. It is also found in small amounts in blood. Because it is resistant to degradation by enzymes, secretory IgA can survive in harsh environments such as the digestive and respiratory tracts, to provide protection against microbes that multiply in body secretions.
• IgA has two subclasses - IgA1 and IgA2.

IgA1 vs. IgA2

• It exists in two isotypes, IgA1 (90%) and IgA2 (10%):
• IgA1 is found in serum and made by bone marrow B cells.
• In IgA2, the heavy and light chains are not linked with disulfide but with noncovalent bonds.
• IgA2 is made by B cells located in the mucosae and has been found to secrete into colostrum, maternal milk, tears and saliva.

T cell

• A type of white blood cell. T cells are part of the immune system and develop from stem cells in the bone marrow.
• They help protect the body from infection and may help fight cancer. Also called T lymphocyte and thymocyte.

• T cells (also called T lymphocytes) are major components of the adaptive immune system.
• Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response.

https://www.telegraphindia.com/india/bharat-biotech-to-launch-indias-first-intranasal-covid-vaccine-on-january-26/cid/1911315