Strong homology between SARS-CoV-2 envelope protein and a Mycobacterium sp. antigen allows rapid diagnosis of Mycobacterial infections and may provide specific anti-SARS-CoV-2 immunity via the BCG vaccine

• Published in: Annals of diagnostic pathology Vol. 48; p. 151600
• Main Authors: Nuovo, Gerard, Tili, Esmerina, Suster, David, Matys, Eva, Hupp, Lance, Magro, Cynthia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2020
• Subjects: AFB; Antibodies, Viral - immunology; Antigens, Viral - immunology; BCG; BCG Vaccine - immunology; Betacoronavirus - immunology; Clinical Laboratory Techniques - methods; Coronavirus Envelope Proteins; Coronavirus Infections - diagnosis; Coronavirus Infections - immunology; COVID-19; COVID-19 Testing; Cross Reactions; Envelope protein; Humans; Immunohistochemistry - methods; Mycobacterium - immunology; Original Contribution; Pandemics; Pneumonia, Viral - immunology; SARS-CoV-2; Tuberculosis - diagnosis; Tuberculosis - immunology; Viral Envelope Proteins - immunology; COVID-19; Envelope protein; SARS-CoV-2; AFB; BCG
• ISSN: 1092-9134; 1532-8198
• DOI: 10.1016/j.anndiagpath.2020.151600

The vaccine BCG has been reported to offer protection against SARS-CoV-2 infection. It has been hypothesized this is based on nonspecific enhancement of innate immunity. This study addressed whether there is strong homology between a SARS-CoV-2 capsid protein and a Mycobacterium bovis protein that would allow for stronger, more specific immune protection. The study also showed the utility of immunohistochemistry in the diagnostic pathology laboratory for elucidating this information. Immunohistochemistry documented that an antibody directed against the SARS-CoV-2 envelope, but not the spike or membrane proteins, strongly cross hybridized to 11/11 Mycobacterial species tested, including M. bovis. BlastP analysis showed high homology of the SARS-CoV-2 envelope protein with 12 consecutive amino acids of the protein LytR C, which is a consensus protein unique to Mycobacteria. Six additional cases of human tuberculosis with few organisms showed that the viral envelope specific antibody (5/6) was more accurate than the AFB stain (2/6) for diagnostic purposes. These data indicate BCG vaccination induces a specific immunity against SARS CoV-2 that targets the viral envelope protein that is essential for infectivity. Thus, a concurrent booster or first use of the BCG vaccine may reduce the severity of the current COVID-19 pandemic. The data also suggests the value of using the SARS-CoV-2 envelope antibody in the diagnosis of Mycobacterial infections in formalin fixed, paraffin embedded tissues by the diagnostic pathologist. •The envelope protein of SARS-CoV2 is strongly homologous with a consensus Mycobacterial protein.•Immunohistochemistry with an antibody against the viral envelope, thus, can detect Mycobacterial infections.•This test is superior to the AFB stain for Mycobacterial detection by the anatomic pathologist.•The BCG vaccine offers a strong, viral specific immunity against COVID-19 due to this strong homology.