[Nosocomial respiratory infection due to coronavirus in neonatal intensive care units: prospective evaluation]

Coronavirus Nsp1: Immune Response Suppression and Protein Expression Inhibition

Coronaviruses have brought severe challenges to public health all over the world in the past 20years. SARS-CoV-2, the causative agent of the COVID-19 pandemic that has led to millions of deaths, belongs to the genus beta-coronavirus. Alpha- and beta-coronaviruses encode a unique protein, nonstructural protein 1 (Nsp1) that both suppresses host immune responses and reduces global gene expression levels in the host cells. As a key pathogenicity factor of coronaviruses, Nsp1 redirects the host translation machinery to increase synthesis of viral proteins. Through multiple mechanisms, coronaviruses impede host protein expression through Nsp1, while escaping inhibition to allow the translation of viral RNA. In this review, we discuss current data about suppression of the immune responses and inhibition of protein synthesis induced by coronavirus Nsp1, as well as the prospect of live-attenuated vaccine development with virulence-attenuated viruses with mutations in Nsp1.

Game of "crowning" season 8: RAS and reproductive hormones in COVID-19 - can we end this viral series?

The outbreak of a newly identified coronavirus, the SARS-CoV-2 (alternative name 2019-nCoV), capable of jumping across species causing zoonosis with severe acute respiratory syndromes (SARS), has alerted authorities worldwide. Soon after the epidemic was first detected in the city of Wuhan in the Hubei Province of China, starting in late December 2019, the virus spread over multiple countries in different continents, being declared a pandemic by March 2020. The demographic characteristics of the infected patients suggest that age, sex, and comorbidities are predictive factors for the fatality of the infection. The mechanisms of viral entry into the human host cells seem to be in a close relationship with the mechanisms of regulating the renin-angiotensin system (RAS), which may explain the pathogenesis associated with the infection. This brings new insights into the possibilities of exploiting viral entry mechanisms to limit associated complications by means of enhancing the resistance of the infected patients using methods of regulating the RAS and strategies of modulating ACE2 expression. In this perspective article we exploit the mechanisms of COVID-19 pathogenesis based on the demographic characteristics of the infected patients reported in the recent literature and explore several approaches of limiting the initial steps of viral entry and pathogenesis based on viral interactions with ACE2 and RAS. We further discuss the implications of reproductive hormones in the regulation of the RAS and investigate the premise of using endocrine therapy against COVID-19.

A human coronavirus responsible for the common cold massively kills dendritic cells but not monocytes

Human coronaviruses are associated with upper respiratory tract infections that occasionally spread to the lungs and other organs. Although airway epithelial cells represent an important target for infection, the respiratory epithelium is also composed of an elaborate network of dendritic cells (DCs) that are essential sentinels of the immune system, sensing pathogens and presenting foreign antigens to T lymphocytes. In this report, we show that in vitro infection by human coronavirus 229E (HCoV-229E) induces massive cytopathic effects in DCs, including the formation of large syncytia and cell death within only few hours. In contrast, monocytes are much more resistant to infection and cytopathic effects despite similar expression levels of CD13, the membrane receptor for HCoV-229E. While the differentiation of monocytes into DCs in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 requires 5 days, only 24 h are sufficient for these cytokines to sensitize monocytes to cell death and cytopathic effects when infected by HCoV-229E. Cell death induced by HCoV-229E is independent of TRAIL, FasL, tumor necrosis factor alpha, and caspase activity, indicating that viral replication is directly responsible for the observed cytopathic effects. The consequence of DC death at the early stage of HCoV-229E infection may have an impact on the early control of viral dissemination and on the establishment of long-lasting immune memory, since people can be reinfected multiple times by HCoV-229E.

[Vertical transmission of human coronavirus. Prospective pilot study]

Les coronavirus humains (HCoV) ont été impliqués dans la survenue d'infections respiratoires nosocomiales chez les nouveau-nés. Plusieurs cas d'infections néonatales ont été mis en évidence. Cette étude pilote recherche l'existence d'une éventuelle transmission maternofœtale des HCoV pouvant expliquer les cas infections néonatales observées dans les premières 24 heures de vie.

Matériel et méthode

Étude monocentrique prospective pilote. Étude des couples mère–enfant par la réalisation de trois prélèvements : vaginal et respiratoire chez la mère (VM et RM) lors du travail, gastrique chez le nouveau-né (GNN). Suivi clinique des nouveau-nés et des mères jusqu'à j3. Analyse virologique des échantillons par reverse transcription-polymerase chain reaction (RT-PCR) en temps réel pour la recherche des HCoV 229-E et OC43.

Résultats

Cent cinquante-neuf couples mère–enfant ont été inclus de juillet 2003 à août 2005. Seul HCoV 229-E a été détecté dans 11 échantillons chez six couples mère–enfant. Pour deux couples, les trois prélèvements (VM, RM et GNN) étaient positifs (cas 1 et 2). Pour le cas 3, seuls le VM et GNN étaient positifs. Pour deux couples, seuls les RM étaient positifs (cas 4 et 5). Pour le cas 6, seul le VM était positif. Pour les trois GNN positifs, aucun enfant n'était symptomatique.

Conclusion

Une possible transmission verticale des HCoV est mise en évidence dans cette étude pilote qui nécessite désormais d'être poursuivie à plus large échelle. Il convient également d'inclure la recherche des coronavirus humains identifiés récemment, HCoV NL63 et HKU1, et d'analyser le profil génomique des HCoV détectés chez les trois couples mère–enfant positifs.