Tonsils are major sites of persistence of SARS-CoV-2 in children

Author(s):Show less -

de Lima, Thais Melquiades ; Martins, Ronaldo Braganca ; Miura, Carolina Sponchiado ; Oliveira Souza, Maria Vitoria ; Anzolini Cassiano, Murilo Henrique ; Rodrigues, Tamara Silva ; Veras, Flavio Protasio ; Sousa, Josane de Freitas ; Gomes, Rogerio ; de Almeida, Glaucia Maria ; Melo, Stella Rezende ; da Silva, Gabriela Conde ; Dias, Matheus ; Capato, Carlos Fabiano ; Silva, Maria Lucia ; Dias de Barros Luiz, Veridiana Ester ; Carenzi, Lucas Rodrigues ; Zamboni, Dario Simoes ; de Melo Jorge, Daniel Macedo ; Cunha, Fernando de Queiroz ; Tamashiro, Edwin ; Anselmo-Lima, Wilma Terezinha ; Pereira Valera, Fabiana Cardoso ; Arruda, Eurico

• Document type: Journal article
• Source: MICROBIOLOGY SPECTRUM; v. 11, n. 5, p. 14-pg., 2023-10-01.

Abstract

In the present study, we show that SARS-CoV-2 can infect palatine tonsils, adenoids, and secretions in children without symptoms of COVID-19, with no history of recent upper airway infection. We studied 48 children undergoing tonsillectomy due to snoring/OSA or recurrent tonsillitis between October 2020 and September 2021. Nasal cytobrushes, nasal washes, and tonsillar tissue fragments obtained at surgery were tested by RT-qPCR, immunohistochemistry (IHC), flow cytometry, and neutralization assay. We detected the presence of SARS-CoV-2 in at least one specimen tested in 27% of patients. IHC revealed the presence of the viral nucleoprotein in epithelial surface and in lymphoid cells in both extrafollicular and follicular regions, in adenoids and palatine tonsils. Also, IHC for the SARS-CoV-2 non-structural protein NSP-16 indicated the presence of viral replication in 53.8% of the SARS-CoV-2-infected tissues. Flow cytometry showed that CD20(+) B lymphocytes were the most infected phenotypes, followed by CD4+ lymphocytes and CD123 dendritic cells, CD8+ T lymphocytes, and CD14+ macrophages. Additionally, IF indicated that infected tonsillar tissues had increased expression of ACE2 and TMPRSS2. NGS sequencing demonstrated the presence of different SARS-CoV-2 variants in tonsils from different tissues. SARS-CoV-2 antigen detection was not restricted to tonsils but was also detected in nasal cells from the olfactory region. Palatine tonsils and adenoids are sites of prolonged RNA presence by SARS-CoV-2 in children, even without COVID-19 symptoms. IMPORTANCE This study shows that SRS-CoV-2 of different lineages can infect tonsils and adenoids in one quarter of children undergoing tonsillectomy. These findings bring advancement to the area of SARS-CoV-2 pathogenesis, by showing that tonsils may be sites of prolonged infection, even without evidence of recent COVID-19 symptoms. SARS-CoV-2 infection of B and T lymphocytes, macrophages, and dendritic cells may interfere with the mounting of immune responses in these secondary lymphoid organs. Moreover, the shedding of SARS-CoV-2 RNA in respiratory secretions from silently infected children raises concern about possible diagnostic confusion in the presence of symptoms of acute respiratory infections caused by other etiologies. (AU)

• FAPESP's process: 19/26119-0 - Emerging and re-emerging viruses: biology, pathogenesis and prospection
• Grantee: Eurico de Arruda Neto
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/07063-1 - Infection of lymphoid tissues by pandemic respiratory viruses: SARS-CoV-2 and Influenza A H1N1
• Grantee: Thais Melquiades de Lima
• Support Opportunities: Scholarships in Brazil - Doctorate