SARS-CoV-2 emerged at the end of 2019 as a new virulent virus that causes coronavirus disease 2019 (COVID-19). Three months later we’re still learning about it; however, the availability of advance technologies has increased the speed of research and therapeutic development. Health officials shared the full sequence of the virus after just one month, jump-starting studies looking for clues on how the virus behaves and can be neutralized, and therapeutic antibody and vaccine candidates are already preparing to enter initial clinical trials three months after we first learned of COVID-19.
So what do we know so far about the virus?
SARS-CoV-2 is spherical with protruding spikes. These spikes, aptly named Spike (S) proteins, interact with a protein on our cells called ACE-2 to enter and infect the cell1. The spike protein also needs to be primed by TMPRSS2, a serine protease, to facilitate fusion of the viral and host cell membrane.
SARS-CoV-2 is also closely related to SARS-CoV-1, another coronavirus, that was responsible for the SARS outbreak in 2003. However, SARS-CoV-2 is about 10X more infectious compared to SARS-CoV and is spreading faster as a result2. The 2003 SARS outbreak lasted about eight months where there were a little over 8,000 cases with 774 deaths in total3. In comparison, there have been over 500,000 COVID-19 cases and over 20,000 deaths in just 3 months4.
The SARS-CoV-2 spike protein has a higher affinity for the ACE-2 protein compared to the SARS-CoV-1 spike protein, making it easier to transmit from person-to-person. Also, coronavirus spike proteins consist of two halves that need to be separated before the virus can infect a host cell. This activation occurs more easily for SARS-CoV-2 due to the enzyme furin, which is found across many tissues in human cells.
The good news is that SARS-CoV-2 is not mutating at a high rate, which means that antibodies elicited by a vaccine will be broadly-neutralizing5. So getting SARS-CoV-2 vaccine will hopefully be more like getting a measles vaccine than a flu vaccine. Check out this article by John Cumbers on the timeline and 3 Paths To COVID-19 Treatment And Prevention – complete with infographic.
1. Hoffman M, et al. SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor, Cell. 2020.
2. Wrapp D, et al. Cryo-EM Structure of the 2019-nCoV Spike in the Perfusion Conformation, Science, 2020.
3. SARS Basics Fact Sheet. CDC. 2017. https://www.cdc.gov/sars/about/fs-sars.html
4. Coronavirus COVID-19 Global Cases by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU). John Hopkins University & Medicine. 2020. https://coronavirus.jhu.edu/map.html
5. Relatively Stable SARS-CoV-2 Genome is Good News for a Vaccine. The Scientist, 2020. https://www.the-scientist.com/news-opinion/relatively-stable-sars-cov-2-genome-is-good-news-for-a-vaccine-67319