TONSILS ARE MAJOR SITES OF PROLONGED SARS-COV-2 INFECTION IN CHILDREN (preprint)

In the present study, we show that SARS-CoV-2 can infect palatine tonsils and adenoids 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. Briefly, nasal cytobrush (NC), nasal wash (NW) and tonsillar tissue fragments obtained at surgery were tested by RT-PCR, immunohistochemistry (IHC), flow cytometry and neutralization assay. We detected the presence of SARS-CoV-2 in at least one specimen tested in 25% of patients (20% in palatine tonsils and 16.27% in adenoids, 10.41% of NC and 6.25% of NW). Importantly, in 2 of the children there was evidence of laboratory-confirmed acute infection 2 and 5 months before surgery. IHC revealed the presence of SARS-CoV-2 nucleoprotein in epithelial surface and in lymphoid cells in both extrafollicular and follicular regions, in adenoids and palatine tonsils. Flow cytometry showed that CD20+ B lymphocytes were the most infected phenotypes by SARS-CoV-2 NP, followed by CD4+ and CD8+ T lymphocytes, and CD14+ macrophages and dendritic cells. Additionally, IF indicated that SARS-CoV-2-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. In conclusion, palatine tonsils and adenoids are sites of prolonged infection by SARS-CoV-2 in children, even without COVID-19 symptoms.

In Vitro Inhibition of SARS-CoV-2 Infection by Bromhexine hydrochloride (preprint)

The world enduring the SARS CoV-2 pandemic, and although extensive research has been conducted on the issue, only a few antivirals have been approved up to date to treat patients with COVID-19. Bromhexine hydrochloride was previously identified as a potent inhibitor of TMPRSS2, an essential protease for ACE-2 virus receptor interactions. In the present study, we investigated whether bromhexine treatment could reduce SARS CoV-2 replication in vitro. To evaluates the effectiveness of bromhexine against SARS COV-2 infection, viral load was measured using Caco-2 cell lines that express TMPRSS2. Our molecular docking results indicate that bromhexine displays an affinity with the active site of TMPRSS2. The drug was able to significantly inhibit SARS CoV-2, both parental and P1 variant strains, infection in the Caco-2 cell line, reducing about 40% of SARS-CoV-2 entrance, and about 90% of viral progeny in the supernatant 48h post-infection. Furthermore, bromhexine did not exhibit any direct virucidal activity on SARS CoV-2. In conclusion, bromhexine hydrochloride efficiently disrupts SARS CoV-2 infection in vitro and has the potential to become an effective antiviral agent in COVID-19 treatment.