Replication of SARS-CoV-2 in human respiratory epithelium

Abstract

30SARS-CoV-2 emerged by the end of 2019 to rapidly spread in 2020. At present, it is of utmost 31 importance to understand the virus biology and to rapidly assess the potential of existing drugs 32 and develop new active compounds. While some animal models for such studies are under 33 development, most of the research is carried out in the Vero E6 cells. Here, we propose fully 34 differentiated human airway epithelium cultures as a model for studies on the SARS-CoV-2. 35 Further, we also provide basic characteristics of the system. 36 37While these viruses are present in the human population for a long time, they are believed to 43 enter the human population in a zoonotic event, and one may speculate that they may have 44 caused epidemics similar to the one observed for the SARS-CoV-2. Time to the most recent 45 ancestor analysis suggests that human coronavirus HCoV-NL63 is the oldest species in humans, 46 followed by its cousin HCoV-229E and two betacoronaviruses, which emerged in humans in a 47 relatively near past 1,2, 3,4 . In the 21 st century, we already faced the emergence of the three novel 48 coronaviruses in humans, of which SARS-CoV disappeared after one season never to come 49 back, and MERS-CoV never fully crossed the species border, as its transmission between 50 humans is highly ineffective 5,6,7 . The 2019 zoonotic transmission, however, resulted in the 51 emergence of a novel human coronavirus, which seems to carry an optimal set of features 52 allowing for its rapid spread with considerable mortality. Whether the virus will become 53 endemic in humans is an open question 8,9,10 . 54At present, the studies on the virus are carried out using a surrogate system based on the 55 immortalized simian Vero E6 cell line 11 . While this model is convenient for diagnostics and 56 testing of some antiviral drugs, it has serious limitations and does not allow for the 57 understanding of virus biology and evolution. To make an example, the entry route of human 58 coronaviruses varies between the cell lines and differentiated tissue, not mentioning the immune 59 responses or virus-host interactions 12,13,14 . 60Here we used the fully differentiated epithelium cultures to study the infection with the 61 novel human coronavirus SARS-CoV-2. We observed an efficient replication of the virus in 62 the tissue, with the maximal replication at 2 days post-infection. At the time of the study no 63 (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.antibodies were available. Therefore we developed immuno-FISH to show that the virus infects 64 primarily ciliated cells of the respiratory epithelium. 66Results and discussion 67 The HAE cultures reconstitute the tissue lining the conductive airways of humans. Fully 68 differentiated, are among the best tools for studying the viral infection in a natural 69 microenvironment 15 . These air-liquid interphase cultures contain a number of cell types (e.g., 70 basal, ciliated, and goblet). At the sa...

Challenges and opportunities for antiviral monoclonal antibodies as COVID-19 therapy

“…Equally importantly, there is ~1000-fold greater virus shed into the apical compartment relative to the basal compartment [ 26 ]. The near exclusive apical infection and shedding of SARS-CoV-1 is consistent with the trafficking of ACE2 to the apical membrane of the human airway epithelium in vivo and in WD-HAE cultures in vitro [ [26] , [27] , [28] ]. Given that SARS-CoV-2 binds the same ACE2 receptor for cellular entry, it is not surprising that SARS-CoV-2 undergoes the same preferential apical infection and shedding [ [26] , [27] , [28] ], and that apical infection of polarized cells in vitro leads to substantially more virus than basolateral infection [ 29 ].…”

Coronavirus Antiviral Research Database (CoV-RDB): An Online Database Designed to Facilitate Comparisons between Candidate Anti-Coronavirus Compounds

“…The 293T cells are typically used for cell–cell fusion and pseudovirus entry experiments. Several studies have also used human alveolar epithelial cells or a variety of different respiratory system or kidney organoids [ 24 , 25 ]. The cell lines used for MERS-CoV are similar, with the main exception that 293T/DPP4 (dipeptidyl peptidase 4) cells are used instead of 293T/ACE2 cells because DPP4 (aka CD26) is the MERS-CoV receptor [ 18 ].…”

Identification of pulmonary comorbid diseases network based repurposing effective drugs for COVID-19

“…Nasal administration of resveratrol to control COVID-19 replication in the early stage of infection and to avoid drug metabolism and availability COVID-19 infected patients expel virus-laden droplets under the right conditions, liquid droplets from sneezes, coughs and just exhaling. The virus-laden droplets deposit to the lining of the nose and throat of the nearby people who inhale them 79,80 . COVID-19 is turned out to be the most lethal disease in the world with about 68% of the mortality are linked to comorbidity 81 .…”