Immunological imprinting is a phenomenon in which earlier exposure to a virus strain (an antigen) results in B-cell memory that provides future protection against related antigens. In other words, the naive immune system bears an indelible “imprint” from the first time it encounters an antigen, such as a viral virus. Antigenic imprinting, immune imprinting, and original antigenic sin (OAS) are further names for immunological imprinting.
Since many epidemiological studies linked immune imprinting with the impact of childhood exposure to the influenza A virus on susceptibility to contract severe influenza infections later in life, Thomas Francis Jr., a renowned scientist, first used the term OAS in relation to the influenza virus in the 1960s. However, the emergence of the severe acute respiratory syndrome coronavirus has recently brought it to public attention.
It seems that original antigenic “sin” carries a bad reputation. It suggests that after being exposed to an antigen for the first time as a youngster, a person develops a lifetime antigenic bias. Even though the original strain is more reactive than newer strains, OAS can still be utilized with the correct vaccine formulation. The researchers also talked about the contrasting findings in the published scientific literature on OAS, which is predominately concerned with the influenza virus.
The time of sampling following a second exposure to an antigen is a confounder when OAS is investigated as a bias in antibody levels. Additionally, the term “biases” has a wide range of meanings; it may refer to anything from a quantifiable difference to a difference in antibody affinities for original vs recall antigens.
OAS can also refer to in vivo antibody recall by a secondary antigen, albeit this is less common. Despite the fact that they bind the primary antigen, these do not exhibit significant in vitro binding to the secondary antigen. The word “sin” has had limited utility in OAS throughout the last two decades due to its connotations. Therefore, it is advisable to steer clear of this phrase and instead use those that have a clear definition and are less likely to be misunderstood.
Immune imprinting’s ability to prevent all immunological reactivity disparities from being converted into epidemiological differences is another important characteristic. Consequently, varying susceptibility to diseases could be seen as a
