DISCUSSION
Anelloviruses, and Torque Teno virus (TTV) in particular, are now
considered potential surrogate markers of cellular immunity in solid
organ transplant recipients. Interestingly, recent reports found that
high levels of TTV in blood are predictive of a poor response to
SARS-CoV-2 vaccination in lung and kidney transplant recipients
(13–15).
In this study, we observed that the TTV load in nasopharyngeal samples
could predict the need for ICU admission in patients infected with
SARS-CoV-2. We established a threshold value as an independent
predictor. This analysis was conducted during the initial wave of the
SARS-CoV-2 pandemic in France and involved patients who were infected
with the virus for the first time. Subsequent to the first wave,
point-of-care testing using nasopharyngeal dry swabs was directly
implemented in the emergency ward to enhance patient care and optimize
bed management (16). Consequently, this prevented the possibility of
conducting further analyses on the same sample. It is imperative to
corroborate these findings using current SARS-CoV-2 variants and after
SARS-CoV-2 vaccination or prior infection, as well as in the context of
other acute respiratory viral infections.
Prior studies have documented the correlation between the detection and
quantification of TTV and viral respiratory tract infections caused by
SARS-CoV-2 and other viruses. In a study conducted before the COVID-19
pandemic, involving children with acute respiratory diseases, Maggi et
al. noted that TTV was more frequently detected and at higher levels in
nasal secretions of patients with bronchopneumonia compared to those
with milder symptoms (8). In an investigation into the respiratory
microbiome and virome signatures associated with the severity of
COVID-19 infection, Merenstein et al. discovered that within a week of
admission, anelloviridae were more prevalent and present in higher
titers in patients with severe disease (17). Furthermore, a recent study
also observed that viruses from the anelloviridae family were
significantly more abundant in samples from deceased and hospitalized
patients in comparison to those from ambulatory individuals (18).
Conversely, in a study that compared TTV plasma loads over a two-week
period between severe and mild-moderate SARS-CoV-2 cases, Solis et al.
demonstrated that a TTV DNA load lower than 700 copies/mL was linked to
a higher risk of severe COVID-19. However, this association was observed
at a time when lymphocyte counts were notably lower in severe cases
during the second week after symptom onset (19).
Collectively, the growing body of evidence suggests that anellovirus
reactivation is linked to an inadequate cellular antiviral response, and
the replication of TTV within the respiratory tract might reflect
respiratory immune deficiency. Detecting and quantifying TTV could serve
as markers for predicting the severity of acute viral respiratory
infections.