INTRODUCTION
SARS-CoV-2 infection is associated with a significant rate of severe
disease requiring intensive care (1,2). While various risk factors have
been identified (3), severe illness can affect anyone, the potential for
severe illness extends to a broad range of individuals, and reliable
individual biological markers to predict unfavorable outcomes remain
lacking. The severity depends, in particular, on an inefficient and
unbalanced immune response. The severity of the disease is notably
influenced by an inadequate and imbalanced immune response. Firstly, an
insufficient interferon response contributes to uncontrolled SARS-CoV-2
replication (4), and secondly, an overactive proinflammatory response
results in damage to respiratory epithelial cells (5).
Anelloviridae, a family of non-enveloped single-stranded DNA viruses,
persistently inhabit various compartments within infected hosts,
constituting a significant component of the human virome (6). Torque
teno virus (TTV), belonging to the Alphatorquevirus genus, ranks among
the most prevalent anelloviruses in humans (7). TTV is not associated
with any specific disease. However, its presence in blood is indicative
of cellular immune function, and TTV load is currently being
investigated in clinical trials for adjusting immunosuppression in solid
organ transplant cases to prevent opportunistic infections and graft
rejection.
The respiratory tract stands as a hypothesized primary entry site for
initial infection and serves as a frequent shedding source (8). TTV is
detectable in respiratory samples from nearly all individuals. Elevated
viral loads have been correlated with lung impairment in patients with
respiratory conditions such as asthma (9) and linked to respiratory
bacterial dysbiosis in lung transplant recipients (10).
Given its affinity for the respiratory mucosa and its connection with
cellular immunity, our study aimed to ascertain whether the assessment
of TTV levels in nasopharyngeal samples upon admission to the emergency
ward could serve as a predictive indicator for identifying the potential
risk of severe disease in patients infected with SARS-CoV-2.