Monoclonal antibodies and their importance in fighting COVID-19

When bacteria or viruses enter the body, the white blood cells in our blood mount an immune response to fight them off. Basically, the bacteria/virus/other pathogen have proteins known as antigens on their surface. And the immune system produces its own proteins, known as antibodies, to target these antigens.

Unlike the antibodies made naturally by the human immune system, monoclonal antibodies (mAb or moAb) are artificially created molecules that can mimic or strengthen the immune system's response; in this case, to the presence of SARS-CoV-2 virus in a COVID-19 positive patient. Monoclonal antibodies are made in a lab.

The term comes from monoclonal, meaning a group of cells formed by a single cell through cellular replication. And antibodies are the proteins produced by plasma cells in the body to fight off foreign pathogens such as different types of bacteria and viruses.

Monoclonal antibodies have been used for the treatment of various types of cancer in the past, as they enable the natural immune system of the human body to fight off cancer.

While antibodies are produced in the body to kill off disease-causing bacteria and viruses, they are also produced to fight off faulty cells in the body like cancer cells. Monoclonal antibodies are derived from cells that have recovered in the body after fighting off infection, and thus, have a specific response to a particular pathogen.

Passive antibody treatments, another line of treatment being administered to COVID-19 patients, have previously been administered to eliminate other diseases such as measles, mumps and influenza.

While there isn’t any literature available on the study conducted by researchers at the Israel Institute of Biochemical Research, scientists from the Netherlands have published their findings. They claimed the human 47D11 antibody - the monoclonal antibody developed by them - "binds a conserved epitope on the spike RBD explaining its ability to cross-neutralize SARS-CoV and SARS-CoV-2, using a mechanism that is independent of receptor-binding inhibition."

SARS-CoV causes severe acute respiratory syndrome (SARS). Epitopes are the specific place on the antigen (the protein on the virus) to which antibodies attach to deactivate or neutralise the pathogen. RBD stands for receptor-binding domain: SARS-CoV and SARS-CoV-2 are both coronaviruses which have spike proteins on their surface. These spike proteins have receptor binding domains that are crucial to how the viruses gain entry into healthy cells of the body. The human 47D11 antibody basically blocks these special RBD domains that the virus would have otherwise used to enter healthy cells.

These neutralizing monoclonal antibodies, they say, work both on an infected individual by "altering the course of infection in the infected host" to fight off the infection, or it can also protect a healthy individual who may have been exposed to the virus. The study goes on to add that this antibody-drug can be administered in combination with other treatments or by itself to prevent or treat symptoms of COVID-19, and even other emerging diseases in the future caused by viruses from the same subgenus.

Previously, researchers had developed a serological test called the ELISA antibody test for COVID-19, which has been used to determine if an individual has developed specific antibodies to the infection, and is thus immune to it.

As the above-mentioned findings explained, the monoclonal antibodies developed specifically for the treatment of COVID-19 are said to work on symptomatic as well as asymptomatic individuals, indicating that such types of drugs perform various functions against diseases and infections.

Monoclonal antibodies can perform several functions even in the treatment of various types of cancers. They can help identify cancer-causing cells in the body, even prompt a response from the body's immune system to destroy the outer lining of cancer cells, besides also blocking the growth of new infected cells.

As noted virologist Dr T. Jacob John explained to the newspaper Mint, "it is a natural extension of convalescent plasma therapy which has shown promising results so far," by giving antibodies passively to patients, as done in the passive antibody treatment performed on COVID-19 patients in the past as well.

Because monoclonal antibodies are also foreign bodies administered into a patient's body, they can also elicit a reaction from the immune system in response. Different monoclonal antibodies used in the treatment of various diseases can have different side effects as a result, some of which include:

• Allergic reactions
• Itching
• Fever
• Chills
• Diarrhoea
• Nausea and vomiting
• Immunological reactions such as serum sickness
• Chances of serious infection if administered with other drugs such as steroids

COVID-19, which is said to have started in Wuhan, China, in late 2019 has now spread all over the world. It has made millions of people sick and caused hundreds of thousands of deaths. Although only 20% of COVID-19 patients need to be hospitalised, the disease has spread quickly and overwhelmed even the best healthcare systems. As a result, countries all over the world have had to shut down borders, suspend travel, and impose unprecedented lockdowns that have caused many an economy to take a nosedive.

As the scientific community is hard at work developing drugs or vaccines that can effectively neutralise the SARS-CoV-2 virus, the development of monoclonal antibodies could be a big win. However, as with many other COVID-19 vaccines and drugs being tested, monoclonal antibodies will also go through rigorous human trials as well as further research before their efficacy in treating ill patients can be firmly established.