On the whereabouts of SARS-CoV-2 in the human body: A systematic review

Abstract

Since SARS-CoV-2 appeared in the human population, the scientific community has scrambled to gather as much information as possible to find good strategies for the containment and treatment of this pandemic virus. Here, we performed a systematic review of the current (pre)published SARS-CoV-2 literature with a focus on the evidence concerning SARS-CoV-2 distribution in human tissues and viral shedding in body fluids. In addition, this evidence is aligned with published ACE2 entry-receptor (single cell) expression data across the human body to construct a viral distribution and ACE2 receptor body map. We highlight the broad organotropism of SARS-CoV-2, as many studies identified viral components (RNA, proteins) in multiple organs, including the pharynx, trachea, lungs, blood, heart, vessels, intestines, brain, male genitals and kidneys. This also implicates the presence of viral components in various body fluids such as mucus, saliva, urine, cerebrospinal fluid, semen and breast milk. The main SARS-CoV-2 entry receptor, ACE2, is expressed at different levels in multiple tissues throughout the human body, but its expression levels do not always correspond with SARS-CoV-2 detection, indicating that there is a complex interplay between virus and host. Together, these data shed new light on the current view of SARS-CoV-2 pathogenesis and lay the foundation for better diagnosis and treatment of COVID-19 patients.

Author summary

Since the beginning of 2020, SARS-CoV-2 quickly spread throughout the human population and caused a pandemic with devastating consequences at a global scale. The scientific community is challenged to find good strategies for the containment and treatment of this virus. In this context, an important step is charting the viral presence in the human body to improve diagnostics, prevention or treatment.

Here, we bring together the current scientific knowledge on SARS-CoV-2 detection in the human body and body fluids. We observe that SARS-CoV-2 impacts the human body well beyond the lungs and shows a complex interplay with the human host that is not always correlated with its entry receptor (ACE2) expression levels. Many studies identified viral components (RNA, proteins) of SARS-CoV-2 in multiple organs (pharynx, trachea, lungs, blood, heart, vessels, intestines, brain, male genitals and kidneys) and body fluids (mucus, saliva, urine, cerebrospinal fluid, semen and breast milk). However, besides the lungs, researchers were only able to detect infectious virus in stool and urine in a limited set of SARS-CoV-2 patients.

By combining these studies, our study provides an eagle’s view on the current status of SARS-CoV-2 pathogenesis and lays the foundation for better diagnosis and treatment of COVID-19 patients.