You asked "Does EBV influence memory B cell formation?
The answer is yes. This is not about MS so if not interested don't read
Burns DM, Tierney R, Shannon-Lowe C, Croudace J, Inman C, Abbotts B, Nagra S, Fox CP, Chaganti S, Craddock CF, Moss P, Rickinson AB, Rowe M, Bell AI. Memory B-cell reconstitution following allogeneic hematopoietic stem cell transplantation is anEBV-associated transformation event Blood. 2015;126(25):2665-75.
In patients with low or undetectable levels of EBV, the circulating B-cell pool consisted predominantly of transitional and naive cells, with a marked deficiency of CD27+ memory cells which lasted >12 months.
However, among patients with high EBV loads, there was a significant increase in both the proportion and number of CD27+ memory B cells. Analysis of sorted CD27+ memory B cells from these patients revealed that this population was preferentially infected with EBV, expressed EBV latent transcripts associated with B-cell growth. These findings suggest that EBV reactivation may drive the expansion of latently infected CD27+ B lymphoblasts in the peripheral blood.