ONE HEALTH APPROACH ON SARS-COV-2 - USING SHEEP AS SENTINEL ANIMALS TO INCREASE FUTURE PANDEMIC PREPAREDNESS - a pilot study

Coronaviruses are a family of viruses that can infect a number of species of birds and mammals with great zoonotic potential to cross species barriers and cause spill-over events. SARS-CoV-2 has been shown to cause clinical and inapparent disease and mortality in several animals cohabitating with humans. Sheep are also susceptible to SARS-CoV-2 and have potential to harbor and spread the virus, as well as develop neutralising antibodies due to similarities of virus-receptor interactions to those in humans. The main aim of this study was to investigate the prevalence of SARS-CoV-2 neutralising antibodies in sentinel animals after natural exposure to the virus. The serum samples were collected from sheep in Central Portugal, Serra da Estrela region, both prior to and during the COVID-19 pandemic. The sheep were kept on dairy farms for production of Serra da Estrela cheese, in small herds and in constant contact with farm workers. The sera were tested using already established SARS-CoV-2 pseudovirus systems for multiple SARS-CoV-2 variants including Wuhan, Delta and Omicron. Partial neutralisation activity towards Wuhan and Delta variants was observed, while neutralisating antibody escape was observed in all Omicron variants tested due to the mutations present . Our results indicate that potential SARS-CoV-2 virus cross-species transmission could have been established through contacts between people and animals on sheep farms. Using farm animals as sentinels is of great importance for implementing One Health Approach in zoonotic virus surveillance and control towards increasing future pandemic preparedness.