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Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21266111


Patients with COVID-19 may develop abnormal inflammatory response and lymphopenia, followed in some cases by delayed-onset syndromes, often long-lasting after the initial SARS-CoV-2 infection. As viral infections may activate human endogenous retroviral elements (HERV), we studied the effect of SARS-CoV-2 on HERV-W and HERV-K envelope (ENV) expression, known to be involved in immunological and neurological pathogenesis of human diseases. Our results have showed that the exposure to SARS-CoV-2 virus activates early HERV-W and K transcription but only HERV-W ENV protein expression, in an infection- and ACE2-independent way within peripheral blood mononuclear cell cultures from one-third of healthy donors. Moreover, HERV-W ENV protein was significantly increased in serum and plasma of COVID-19 patients, correlating with its expression in CD3+ lymphocytes and with disease severity. Finally, HERV-W ENV was found expressed in post-mortem tissues of lungs, heart, brain olfactory bulb and nasal mucosa from acute COVID-19 patients in cell-types relevant for COVID-19-associated pathogenesis within affected organs, but different from those expressing of SARS-CoV-2 antigens. Altogether, the present study revealed that SARS-CoV-2 can induce HERV-W ENV expression in cells from individuals with symptomatic and severe COVID-19. Our data suggest that HERV-W ENV is likely to be involved in pathogenic features underlying symptoms of acute and post-acute COVID. It highlights the importance to further understand patients genetic susceptibility to HERV-W activation and the relevance of this pathogenic element as a prognostic marker and a therapeutic target in COVID-19 associated syndromes.

Preprint Dans Anglais | medRxiv | ID: ppmedrxiv-21266918


Massive testing is a cornerstone in efforts to effectively track infections and stop COVID-19 transmission, including places where good vaccination coverage has been achieved. However, SARS-CoV-2 testing by RT-qPCR requires specialized personnel, protection equipment, commercial kits, and dedicated facilities, which represent significant challenges for massive testing implementation in resource-limited settings. It is therefore important to develop testing protocols that facilitate implementation and are inexpensive, fast, and sufficiently sensitive. In this work, we optimized the composition of a buffer (PKTP) containing a protease, a detergent, and an RNase inhibitor, that is compatible with the RT-qPCR chemistry, allowing for direct testing of SARS-CoV-2 from saliva in an RNA extraction-independent manner. This buffer is compatible with heat-inactivation reducing the biohazard risk of handling the samples. We assessed the PKTP buffer performance in comparison to the RNA-extraction-based protocol of the US Centers for Disease Control and Prevention in saliva samples from 70 COVID-19 patients finding a good sensitivity (82.2% for the N1 and 84.4% for the N2 target, respectively) and correlations (R=0.77, p<0.001 for N1, and R=0.78, p<0.001 for N2). We also propose an auto-collection protocol for saliva samples and a multiplex reaction to reduce the number of PCR reactions per patient and further reduce overall costs while maintaining diagnostic standards in favor of massive testing.

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