Detection and identification of coronaviruses in human tissues using electron microscopy

Area of Science:

• Pathology
• Virology
• Microscopy

Background:

• Accurate identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particles in patient tissues via electron microscopy (EM) is challenging.
• Misidentification of cellular structures as SARS-CoV-2 particles is common in published literature.
• Distinguishing viral particles from subcellular organelles requires expertise in viral ultrastructure and cell biology.

Purpose of the Study:

• To provide clear morphological criteria for differentiating coronavirus particles from common subcellular structures in EM images.
• To review ultrastructural changes observed in SARS-CoV-2 infected tissues, clarifying direct viral infection evidence.
• To aid researchers in accurate identification of SARS-CoV-2 in pathological specimens.

Main Methods:

• Review of published literature on SARS-CoV-2 ultrastructure and pathological findings.
• Analysis of morphological features of coronaviruses using electron microscopy.
• Comparison of viral particle morphology with common subcellular organelles.

Main Results:

• Specific ultrastructural features of coronaviruses are described to aid differentiation from vesicles and endoplasmic reticulum.
• Review highlights that observed tissue damage does not always equate to direct viral infection.
• Widespread ultrastructural changes in various organs suggest complex SARS-CoV-2 pathogenesis.

Conclusions:

• Accurate identification of SARS-CoV-2 particles by EM is crucial and requires careful morphological assessment.
• Understanding viral ultrastructure is key to avoiding misinterpretation of cellular components.
• Observed tissue alterations may result from direct infection or indirect immune/inflammatory responses to SARS-CoV-2.