1 Introduction
The coronavirus disease (COVID-19) outbreak starting in 2019 was declared as public health emergency by the World Health Organization (WHO) on January 30, 2020, infecting more than 16.5 million people and continuing to spread throughout the world (WHO 1a, 2020; WHO 1b, 2020). The disease COVID-19 was first described in Wuhan, China, in patients that had respiratory tract infection and pneumonia (Zhou et al., 2020; Andersen et al., 2020). It is caused by a novel betacoronavirus known as severe acute respiratory syndrome virus 2 (SARS-CoV-2) that is genetically related to bat coronavirus RaTG13 and other betacoronaviruses that are found in bats (Zhou et al., 2020; Andersen et al., 2020; Lu et al., 2020).
Viruses in the coronavirus family are enveloped, single stranded positive sense RNA viruses with genomes ranging between 26 to 32 kb (Su et al., 2016; Fehr et al., 2015). The coronavirus family contains a wide range of viruses that are pathogenic to a variety of animal species including humans. However, many of these viruses tend to have limited host range and can cause severe diseases only in domestic animals, resulting in large production losses to producers. Some animal coronaviruses such as transmissible gastroenteritis virus (TGEV), bovine coronavirus (BCoV), feline coronavirus, canine coronavirus and turkey coronavirus cause enteritis in their respective hosts (Su et al., 2016). Others such as avian infectious bronchitis and canine respiratory coronavirus cause respiratory diseases in their respective hosts (Su et al., 2016).
Prior to 2003, viruses of the coronavirus family were not known to cause severe disease in humans. However, since the beginning of the 21st century three viruses from the betacoronavirus subfamily, Severe Acute Respiratory Syndrome virus (SARS), Middle Eastern Respiratory Syndrome virus (MERS) and SARS-Cov-2 have crossed the species barrier to infect humans (Kin et al., 2015; Peiris et al., 2003; Zhou et al., 2020).
When a novel virus results in an outbreak or pandemic, assessing the risk of the novel agent to infect other species is of paramount importance in order to control the disease. Since the emergence of SARS-CoV-2, a number of studies have been conducted as part of the risk assessment to determine if domestic animals that are used as companion animals in households or as source of food are susceptible to the virus. Additional studies were also conducted in laboratory animals such as mice, ferrets, non-human primates and others in search of animal models that could be used to study virus pathogenesis, vaccine efficacy studies and prophylaxis of the disease.
The purpose of this study was to determine if domestic poultry such as turkeys and chickens are susceptible to SARS-CoV-2 virus and play any potential role in the dissemination of the virus. In addition, the susceptibly of chicken embryos to SARS-CoV-2 was evaluated to determine if eggs could potentially be used for the production of potential SARS-CoV-2 vaccines.