RESUMO
Molecular epidemiology has provided an additive value to traditional public health tools by identifying SARS-CoV-2 clusters, or providing evidence that clusters based on virus sequences and contact tracing are highly concordant. Our aim was to infer the levels of virus importation and to estimate the impact of public health measures related to travel restrictions to local transmission in Greece. Our phylogenetic and phylogeographic analyses included 389 SARS-CoV-2 sequences collected during the first 7 months of the pandemic in Greece and a random collection in 5 replicates of 3,000 sequences sampled globally, as well as the best hits to our dataset identified by BLAST. Phylogenetic analyses revealed the presence of 70 genetically distinct viruses identified as independent introductions into Greece. The proportion of imported strains was 41%, 11.5%, and 8.8% during the three periods of sampling, namely, March (no travel restrictions), April to June (strict travel restrictions), and July to September (lifting of travel restrictions based on a thorough risk assessment), respectively. These findings reveal low levels of onward transmission from imported cases during summer and underscore the importance of targeted public health measures that can increase the safety of international travel during a pandemic.
RESUMO
BackgroundSevere COVID-19 pneumonia has been associated with the development of intense inflammatory responses during the course of infections with SARS-CoV-2. Given that Human Endogenous Retroviruses (HERVs) are known to be activated during and participate in inflammatory processes, we examined whether HERV dysregulation signatures are present in COVID-19 patients. ResultsBy comparing transcriptomes of Peripheral Blood Monocytes (PBMCs) and Bronchoalveolar Lavage Fluid (BALF) from patients and normal controls we have shown that HERVs are intensely dysregulated in BALF, but not in PBMCs. In particular, upregulation in the expression of multiple HERV families was detected in BALF samples of COVID-19 patients, with HERV-W being the most highly upregulated family among the families analysed. In addition, we compared the expression of HERVs in Human Bronchial Epithelial Cells (HBECs) without and after senescence induction in an oncogene-induced senescence model, in order to quantitatively measure changes in the expression of HERVs in bronchial cells during the processes of cellular senescence. ConclusionsThis apparent difference of HERV dysregulation between PBMCs and BALF warrants further studies in involvement of HERVs in inflammatory pathogenetic mechanisms as well as exploration of HERVs as potential biomarkers for disease progression. Furthermore, the increase in the expression of HERVs in senescent HBECs in comparison to non-induced HBECs provides a potential link for increased COVID-19 severity and mortality in aged populations.