In Situ Detection of SARS-CoV-2 RNA in Tissues

Paraffin-embedded tissues were sectioned at 5 μm and subjected to ISH using the RNAscope ZZ probe technology (Advanced Cell Diagnostics, Newark, CA). In situ hybridization was performed to detect tissue distribution of SARS-CoV-2 RNA in tissues from tissue tropism study (tissue distribution and tropism of SARS-CoV-2 in WTD). Nasal turbinate, palatine tonsil, medial retropharyngeal, mandibular and tracheobronchial lymph nodes, and lung were tested by RNAscope 2.5 HD Reagents–RED kit (Advanced Cell Diagnostics) as previously described [10 (link)]. Proprietary ZZ probes targeting SARS-CoV-2 RNA (V-nCoV2019-S probe ref # 848561) or anti-genomic RNA (V-nCoV2019-S-sense ref # 845701) designed and manufactured by Advance Cell Diagnostics were used for detection of viral RNA. A positive control probe targeted the Bos taurus–specific cyclophilin B (PPIB Cat# 3194510) or ubiquitin (UBC Cat # 464851) housekeeping genes, while a probe targeting dapB of Bacillus subtilis (Cat # 312038) was used as a negative control.