Your T cells went to EBV and Flu Back again

95% of people in the world have EBV by the age of 30, but only a fraction of these individuals present with symptoms or illness (i.e. infectious mononucleosis). Notably, the vast majority of kids who are infected (which is when a lot of people get it) experience no symptoms at all. Similarly, in adults, EBV infection can also present as a minor to nonexistent illness. That said, the scientific community does not know what exactly predisposes some individuals to developing a syndrome-producing mono infection as opposed to an asymptomatic infection. Likewise, that's exactly what a research team in the University of Massachusetts Medical School were investigating in their analysis of T-cells found to be reactive to both influenza A and EBV.

Frequently, T-cells are virus (or pathogen)-specific in their cellular receptors; likewise, the effector memory T-cells that are produced after an infection is cleared theoretically retain this specificity. Memory T-cells (like memory plasma cells/B cells) are responsible for initiating a more rapid, more robust immune response upon a secondary, tertiary, or quaternary (and beyond) infection of a pathogen the body has encountered before. So, a flu memory T-cell would optimally be effective against the exact same strain of flu if infected again.

This medical school team, however, has found that some T-cells are cross-reactive to both EBV and influenza A, and an increase in that population of T-cells results in more severe immune response (and more severe symptoms). Specifically, children with severe cases of mono (from EBV) had 25 times more of these cross-reactive cells than those who experienced no symptoms (and those with mild symptoms had 10 times more).

How do you avoid these cross-reactive cells and severe infection? By avoiding the flu!!! (or EBV!) One of these easier than the other because we have a vaccine for it (you should know which one that is).

EBV, in addition to causing mono, has several interesting factoids. First, it's a herpesvirus (human herpesvirus 4) and has known latency in tonsil cells. This means it can recurrently appear in times of stress both in its shedding and its presentation of symptoms; it's an infection that is never actually cleared. Furthermore, EBV has been associated with some cancers and autoimmune diseases, such as Hodgkin lymphomas and multiple sclerosis, respectively. All this from the infamous "kissing virus".

While this is only a drop in the bucket to understanding EBV infection and variability in symptoms, it's a start!

Miss ya, kiss ya, wouldn't want to E  B V ya!

-javarcia


https://www.sciencedaily.com/releases/2017/12/171205104219.htm