Introduction
The novel 2019 SARS-CoV-2 coronavirus which causes significant morbidity and mortality has been declared a pandemic by the World Health Organization (Chan et al., 2020). Due to the highly infectious nature of this contagion, urgent and coordinated efforts are required to develop a vaccine against SARS-CoV-2.
SARS-CoV-2 is genetically related to the SARS-CoV coronavirus which infected 8096 in 25 countries around the world (Tang et al., 2020). Coronaviruses are RNA viruses with characteristic spikes on their envelopes resembling a crown-like structure (Siddell, 1995). They are zoonotic and therefore most likely crossed from animals such as bats into humans through intermediaries (Andersen, Rambaut, Lipkin, Holmes, & Garry, 2020; Huynh et al., 2012; Lai, Bergna, Acciarri, Galli, & Zehender, 2020). Clinical features of SARS-CoV-2 range from asymptomatic to severe respiratory distress syndrome (Wu et al., 2020).
The mode entry of SARS-CoV-2 has been recently shown to be through its direct interaction of the surface glycoprotein with human angiotensin-converting enzyme 2 (hACE2) (Hoffmann et al., 2020; Yan et al., 2020). This mode of entry is the same as hCoV-NL63 and SARS-CoV coronaviruses (Hofmann et al., 2005; Kuba et al., 2005). The receptor-binding domain of the surface glycoprotein was shown to be important for the entry of SARS-CoV-2 into the host cells as evidence by the crystal structure of the SARS-CoV-2 RBD domain in complex with hACE2 (Tai et al., 2020). Since the surface glycoprotein is surfaced exposed, it makes an ideal candidate for the development of neutralizing antibodies, therapeutic drug design and vaccine development (Ahmed, Quadeer, & McKay, 2020). However, due to the emergence of high mutation rates in RNA viruses, therapeutic modalities might be hampered (Elena & Sanjuán, 2005). Furthermore, antigen drift as has been a problem in the development of influenza vaccines needs to be considered in SARS-CoV-2 (Hensley et al., 2009).
This study analyzed the surface glycoprotein from emerging isolates of SARS-CoV-2 sequenced globally. Mutations in several isolates were detected from different geographical locations, which might have important implications for vaccine design and therapeutic development.