Data on features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children and adolescents are scarce. We report preliminary results of an Italian multicentre study comprising 168 laboratory-confirmed paediatric cases (median: 2.3 years, range: 1 day–17.7 years, 55.9% males), of which 67.9% were hospitalised and 19.6% had comorbidities. Fever was the most common symptom, gastrointestinal manifestations were frequent; two children required intensive care, five had seizures, 49 received experimental treatments and all recovered.

No abstract

In humans, the interaction of the natural killer group 2 member D (NKG2D)-activating receptor on natural killer (NK) and CD8(+) T cells with its major histocompatibility complex class I-related chain (MIC) and UL16 binding protein (ULBP) ligands (NKG2DLs) promotes recognition and elimination of stressed cells, such as tumor or infected cells. Here, we investigated the capacity of HIV-1 to modulate NKG2DL expression and escape NGK2D-mediated immunosurveillance. In CD4(+) T lymphocytes, both cell surface expression and release of MICA, MICB, and ULBP2 were up-regulated >2-fold by HIV-1 infection. In HIV-infected CD4(+) T lymphocytes or Jurkat T-cell lines, increased shedding of soluble NKG2DLs (sNKG2DLs) was impaired by a matrix metalloproteinase inhibitor (MMPI). Moreover, naive HIV(+) patients displayed increased plasma sMICA and sULBP2 levels and reduced NKG2D expression on NK and CD8(+) T cells compared to patients receiving highly active antiretroviral therapy (HAART) or healthy donors. In individual patients, HAART uptake resulted in the drop of sNKG2DL and recovery of NKG2D expression. Finally, sNKG2DLs in patients' plasma down-regulated NKG2D on NK and CD8(+) T cells and impaired NKG2D-mediated cytotoxicity of NK cells. Thus, NKG2D detuning by sNKG2DLs may promote HIV-1 immune evasion and compromise host resistance to opportunistic infections, but HAART and MMPI have the potential to avoid such immune dysfunction.

Our results suggest a link between nef gene functions and the progression rate in HIV-1-infected children. Moreover, non-progressor-associated variations in the core domain of Nef, together with the genetic analysis, suggest that nef gene evolution is shaped by an effective immune system in these patients.