Longitudinal SARS-CoV-2 infection study at Ulm University

In light of the COVID-19 pandemic, universities around the world were challenged by the difficult decision whether classes could be held face-to-face in the winter semester 20/21. The gross anatomy course is considered an essential practical element of medical school. In order to protect the participants and teaching staff and to gain more knowledge about SARS-CoV-2 infections among students during a semester with face-to-face teaching a longitudinal test study was conducted. Medical students from the first three years of medical school were also invited. Out of a total of almost 1,000 swabs, only two active asymptomatic infections were detected at the start of the semester, none during the semester. At semester start, approximately 6% of the students had antibodies. At the end of the semester, only nine seroconversions after infection in 671 individuals occurred. This was surprisingly low because a massive second wave of infections hit Germany during the same period. The conclusion therefore is that face-to-face teaching under these measures was not infection-promoting even with high incidence rates in the overall population with the SARS-CoV-2 variants present at that time period. Moreover, the results are indicative of a preventive effect of hygiene concepts together with repetitive testings before and during a semester.

IFITM proteins promote SARS-CoV-2 infection in human lung cells

Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) are thought to restrict numerous viral pathogens including severe acute respiratory syndrome coronaviruses (SARS-CoVs). However, most evidence comes from single-round pseudovirus infection studies of cells that overexpress IFITMs. Here, we verified that artificial overexpression of IFITMs blocks SARS-CoV-2 infection. Strikingly, however, endogenous IFITM expression was essential for efficient infection of genuine SARS-CoV-2 in human lung cells. Our results indicate that the SARS-CoV-2 Spike protein interacts with IFITMs and hijacks them for efficient viral entry. IFITM proteins were expressed and further induced by interferons in human lung, gut, heart and brain cells. Intriguingly, IFITM-derived peptides and targeting antibodies inhibited SARS-CoV-2 entry and replication in human lung cells, cardiomyocytes and gut organoids. Our results show that IFITM proteins are important cofactors for SARS-CoV-2 infection of human cell types representing in vivo targets for viral transmission, dissemination and pathogenesis and suitable targets for therapeutic approaches.