Definition of Immune Imprinting
The objective of this week’s assignment is to understand the importance and role of definitions when it comes to communicating technical terms to non-technical readers. This assignment offers students the opportunity to hone their technical writing abilities by describing a complex term in their particular discipline using a parenthetical definition, sentence definition, and an expanded definition that includes a visual and four expansion strategies.
The term I have chosen is immune imprinting. The context of this situation is a clinical virologist explaining the term to first-year university students during a guest lecture.
What is immune imprinting?
Immune imprinting is a phenomenon in which the body recalls immune cells from a previous exposure to a virus rather than producing new immune cells in response to the current virus. The outcome of subsequent viral exposures can be shaped by immune imprinting (recall of previously-made antibodies rather than inducing new antibody responses) as pre-existing memory may interfere with the production of more effective immune responses and reduce vaccine efficacy (Zhang et al., 2019).
Expanded Definitions
Etymology
The term immune comes from the Latin word immunis meaning “exempt from public service or charge”. Imprint is derived from the Old French word empreinter, based on Latin imprimere, meaning “to press into”. Together, immune imprinting refers to the impression on the immune system of being exempt from disease.
History
Immune imprinting was originally termed “original antigenic sin” by Thomas Francis in 1960 during his work with hemagglutination inhibition assays against seasonal influenza strains (Francis, 1960). The scientific community has since moved away from the theologically-charged name given by Francis, who was the son of a Presbytarian minister. The phenomenon of immune imprinting has been highly investigated since its discovery and its implications are still significant in modern-day virology and vaccine development.
Comparison and Contrast
Imagine that the immune cells in our bodies are individual soldiers that defend our bodies from invading viruses that can attack and cause disease. The first time these soldiers meet a virus, they may recognize the foreign enemies’ armour, the viral antigens, and generate the most efficient weapons, antibodies, to combat that specific threat. Now, when these soldiers meet another virus with similarly-shaped armour, they mistake it for the first enemy and instead of generating the most efficient weapons to combat this new threat, they rely on the old weapons that worked against the enemy the first time. This mistaken identity is similar to how immune imprinting can shape our immune response to subsequent viruses.
Examples
Immune imprinting has been suggested to confer protection to elderly adults in the 2009 H1N1 pandemic who were alive and exposed to earlier H1 viruses during the 1918 Spanish Flu pandemic (Adalja & Henderson, 2010). Most recently, scientists have used the theory of immune imprinting to predict how newly developed vaccines will interact with the immune system to generate the most effective response to SARS-CoV-2 infection (Aydillo et al. 2021).
Visuals
The following image shows how antibody concentrations in the body can be boosted by sequential exposure to similar pathogens. Although Virus A, A’ and A” are ultimately different viruses, their antigens (surface proteins) are similar enough that the immune system produces antibodies against Virus A and A’ even when Virus A” is encountered. As shown in the graph on the right, this results in high levels of Virus A and Virus A’ antibodies and low levels of Virus A” antibodies during a Virus A” infection.
Figure 1. Levels of Antibodies in the Body After An Immune Response. (Source: Zhang et al. 2019, J Immunol)
Figure 1. Levels of Antibodies in the Body After An Immune Response. (Source: Zhang et al. 2019, J Immunol)
Works Cited
Adalja, A. A., & Henderson, D. A. (2010). Original Antigenic Sin and Pandemic (H1N1) 2009. Emerging Infectious Diseases, 16(6), 1028–1029. https://doi.org/10.3201/eid1606.091563
Francis, T. (1960). On the Doctrine of Original Antigenic Sin. Proceedings of the American Philosophical Society, 104(6), 572–578.
Zhang, A., Stacey, H. D., Mullarkey, C. E., & Miller, M. S. (2019). Original Antigenic Sin: How First Exposure Shapes Lifelong Anti–Influenza Virus Immune Responses. The Journal of Immunology, 202(2), 335–340. https://doi.org/10.4049/jimmunol.1801149
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