Question

Discuss the significance of antigenic drift and antigenic shift

Answer 1

Antigens are those molecules which enter the body and induce an immunological effect in the body. As an effect, antibodies are generally generated in the body which fight against the antigen. Viruses contain such antigens against which the body tends to develop antibodies. However, there are some phenomenon by which the viral particles undergo rapid change in their antigenic make up and hence the host fails to develop antibodies. These processes are as discussed below:

Antigenic drift: According to this mechanism, the rapid and faulty nucleic acid replication in the virus induces random mutations in it thus inducing a structural change in the antigenic make up. This new antigen is then not recognized by the host since its structural make up has been altered as compared to previous. Thus, the body considers it as a new infection and hence the immune response dampens. This is why vaccines and medicines are not available against some rapidly dividing and mutating viruses such as influenza virus.

Antigenic shift: According to this mechanism, two or more viral species interact and fuse with each other to generate a new viral class or modify the pre-exisiting class with presence of new antigenic locations. These new antigens are not recognized by host body and hence infection elevates. This type of process is particularly more deleteriuos in nature since viruses from variuos sources such as animal viruses, human viruses, bird viruses can combine and cause a co-infection, which has highly deleterious effect on the immune system.