In silico assessment of immune cross protection between BCoV and SARS-CoV-2
BackgroundHumans have long shared infectious agents with cattle, and the bovine-derived human common cold OC-43 CoV is a not-so-distant example of cross-species viral spill over of coronaviruses. Human exposure to the Bovine Coronavirus (BCoV) is certainly common, as the virus is endemic in most high-density cattle-raising regions. Since BCoVs are phylogenetically close to SARS-CoV-2, it is possible that cross-protection against COVID-19 occurs in people exposed to BCoV. MethodsThis article shows an in silico investigation of human cross-protection to SARS-CoV-2 due to BCoV exposure. We determined HLA recognition and human B lymphocyte reactivity to BCoV epitopes using bioinformatics resources. A retrospective geoepidemiological analysis of COVID-19 was then performed to verify if BCoV/SARS-CoV-2 cross-protection could have occurred in the field. Brazil was used as a model for the epidemiological analysis of the impact of livestock density - as a proxy for human exposure to BCoV - on the prevalence of COVID-19 in people. ResultsAs could be expected from their classification in the same Betacoronavirus genus, we show that several human B and T epitopes are shared between BCoV and SARS-CoV-2. This raised the possibility of cross-protection of people from exposure to the bovine coronavirus. Analysis of field data added partial support to the hypothesis of viral cross-immunity from human exposure to BCoV. There was a negative correlation between livestock geographical density and COVID-19. Whole-Brazil data showed areas in the country in which COVID-19 prevalence was disproportionally low (controlled by normalization by transport infrastructure). Areas with high cattle density had lower COVID-19 prevalence in these low-risk areas. ConclusionsThese data are hypothesis-raising indications that cross-protection is possibly being induced by human exposure to the Bovine Coronavirus.