Microbiology

Microbiology Study Guide

In contrast, when a person is exposed to a vaccine against any infection or disease, then the immunity that is developed in the human body is known as artificially acquired active immunity. The vaccine may consist of bacteria, virus, or toxoids. This immunity is known as artificially acquired since the exposure to the vaccine does not happen during the normal scheme of events. As opposed to active immunity, passive immunity is activated when antibodies enter the body. This immunity lasts for a brief period of time and protects the body from infections and diseases for that short timeframe. In this type of immunity, the immune system does not get activated. It can also be divided into two categories: naturally acquired passive immunity and artificially acquired passive immunity. Detecting Antibodies with Laboratory Tests Antibodies within the body can be tested and detected with different laboratory tests and diagnostic procedures. It should be noted that there is a positive relationship between the presence of an antibody and disease in the body. When the serum of the antibody is studied, the study is known as serology. Serology is concerned with the presence of titer antibody in a person, which denotes the estimated level of antibody. It is represented in terms of a unit volume of serum that is 1:100. There are different types of serological tests. Agglutination tests are done to detect the clumping of an antigen; the antibodies detected in this test are known as agglutinins. In this test, the molecules of the antibodies fuse with the molecules of the antigens, either on the bacterial surface, red blood cells, or particles, and become large clumps. The precipitation test helps detect antibodies known as precipitins in fluids and gels. In this test, the antibodies react with the dissolved antigens and form large sized complexes, so that they become easily visible as precipitate particles. The third category of serological tests is the complement fixation test, in which the fusion with antigens and antibodies is done in the presence of complement-like blood proteins. If the antibodies react and fuse with the complement, the test will reflect positive results. The last type of serological test is known as the fluorescent antibody technique. The reaction between antibody and antigen can be detected using this test. In this test, the solution of the antibody is fused with the antigen containing cells. If a reaction happens, the outcome shows the accumulation of fluorescent dye on the surface.

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