Distinct T cell polyfunctional profile in SARS-CoV-2 seronegative children associated with endemic human coronavirus...

Area of Science:

• Immunology
• Virology
• Pediatrics

Background:

• SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection in children often presents as asymptomatic or mild illness.
• Limited research exists on SARS-CoV-2 antiviral immunity, specifically T-cell responses, in African children.
• Understanding T-cell responses is crucial for comprehending protective immunity against SARS-CoV-2 in pediatric populations.

Purpose of the Study:

• To investigate SARS-CoV-2-specific T-cell responses in unvaccinated, asymptomatic South African children.
• To compare T-cell responses between SARS-CoV-2 seropositive and seronegative children.
• To explore potential cross-reactivity with endemic human coronaviruses.

Main Methods:

• Analysis of SARS-CoV-2-specific CD4+ T-cell responses in 71 unvaccinated children.
• Categorization of children into SARS-CoV-2 seropositive and seronegative groups.
• Assessment of T-cell functional profiles and association with endemic human coronavirus (HCoV) HKU1 IgG response.

Main Results:

• SARS-CoV-2-specific CD4+ T-cell responses were detected in 83% of seropositive and 60% of seronegative children.
• While response magnitude did not differ significantly, seropositive children showed more polyfunctional T-cells.
• T-cell frequency in seronegative children correlated with HCoV HKU1 IgG levels.

Conclusions:

• SARS-CoV-2-specific T-cells are present in both seropositive and seronegative South African children.
• Cross-reactivity with endemic coronaviruses likely contributes to T-cell responses in seronegative children.
• These T-cell responses may play a role in the observed mild SARS-CoV-2 disease presentation in children.