"Association between Epstein‐Barr‐Virus reactivation and development of Long‐COVID fatigue"
pmc.ncbi.nlm.nih.gov
SARS‐CoV‐2 RNA was detectable neither in throat washing nor stool in any of the study participants by real‐time RT‐PCR. SARS‐CoV‐2 antibody titres (IgA and IgG) did not differ between the cohorts (Figure S1) ... EBV real‐time PCR was negative in all blood or stool samples. However, EBV DNA was detected in throat washings in 15/30 (50%) of Long‐COVID patients while only in 4/20 (20%) of non‐Long‐COVID patients who had recovered from their SARS‐CoV‐2 infection (p = .0411). EBV load levels were not significantly different between the two cohorts in EBV‐specific real‐time PCR positive samples (Figure 1). All patients of both groups, except one patient in the fully convalescent COVID‐19 group (SARS‐CoV‐2 – LC), had past EBV infections, as confirmed by EBV IgG seropositive and IgM seronegative status at the time of investigation, thus, the EBV replication observed was due to EBV reactivation rather than primary infection. EBV specific antibody titres as assessed by microarray in blood were not different between the groups (Figure S2).
There seems to be a flaw in this logic.
You cannot rule out EBV reinfection with
this evidence. So the premise that this is proof of reactivation is not watertight, likely maybe but conclusive, I don't think so.
Secondly the literature suggests EBV reactivation is a complex phenomenon. EBV is reported to reactivate in a lytic phase which produces and spreads virus by using up and killing the cell. However it can apparently persist in at least four different types of latent phase with varying degrees of viral protein synthesis.
The paper discusses
EBV load levels suggesting no significant difference in load between positive samples in both cohorts, which presumably is a measure intended to distinguish different modes of EBV DNA release such as apoptosis of cells carrying latent infection from lytic reactivation, it does not quantitatively identify these modes but seems to show the 20% of covid recovered patients with EBV had the same EBV production process as the 50% of longcovid patients, whichever it was.
This suggests EBV does not cause longcovid, otherwise the 20% recovered with EBV would not be recovered. It suggests EBV might be reproducing more often in people with longcovid.
This is correctly termed an association and to my mind looks like a sign of something wrong in longcovid patients triggering either opportunist EBV lytic reactivation or apoptosis of cells with latent EBV infections but not direct evidence EBV is the cause of longcovid.
Does that make sense? Honestly I found it a bit confusing but interesting, given my own experience of various recurring viruses.