Antibody Responses

At this point everyone has heard and most likely been affected by COVID-19, but may not know about the antibodies specific for this virus. When someone gets a viral or bacterial infection, the body will immediately start creating an immune response. The body wants to get rid of the invader as quickly as possible before it takes over and causes too much damage. With coronavirus, IgM and IgG are the antibodies being generated by this virus.

IgM is the first antibody produced to fight of a new infection. Although this isn’t the greatest antibody, it is better than nothing and is quick to respond to new infections. IgG is generated and will replace IgM. Once a B cell is activated by a mature T helper cell, it will start to create tons of clones while also class switching and undergoing affinity maturation. All these clones will only make the antibody it is told to make from the original B cell. Class switching and affinity maturation allow the B cell to produce to best antibody to respond to the infection. With Coronavirus, this antibody appears to be IgG. If only IgM is present, the infection is new and hasn’t had enough time to class switch and undergo affinity maturation. If you have both IgM and IgG, the B cells are changing their antibodies and switching IgM with IgG. Primarily having IgG would mean you have been infected long enough for your B cells to switch their antibody response. High levels of IgG can mean you have a chronic infection.

Many labs are attempting to develop blood tests to identify if someone has been infected by the coronavirus. Currently there are two tests, a polymerase chain reaction (PCR) test and a serological test. The PCR test is looking for any of the viruses RNA genetic material. A nasal or throat swab is used and can determine if someone has an active infection. The serological test is a blood test trying to find any antibodies that have been produced against COVID-19. If antibodies are found, this is an indication that the individual has had the infection previously. The PCR test is more useful when it comes to diagnosing someone since it takes multiple days for antibodies to be produced. The serological test would be better to see whether someone had the virus in the past, even if they were asymptomatic.

Detecting if someone has produced antibodies against coronavirus, may help them return to work faster. The amount of time this immunity lasts is still unknown. Using the serological test may also help professionals start to determine the amount of asymptomatic carriers. The blood plasma of those who have recovered from COVID-19 can now be injected into others. The FDA has approved this as a temporary antiviral treatment. This treatment has been approved for individuals who have serious infections. Houston, New York and Seattle are already using this form of treatment. There is still additional research needed to be done, but antibody research seems to be leading us in the right direction.