Question

Find SARS-CoV-2 on the phylogeny above – this is the virus that causes COVID-19. There have been two previous major coronavirus outbreaks in 21st century – SARS in 2002-2003 (caused by the virus SARS-CoV) and MERS in 2012-2013 (caused by the virus MERS-CoV).

(a)Based on the phylogeny above, how do we know that COVID-19 is a new disease and not a resurgence of SARS or MERS? Be specific and refer to the relationships shown on the phylogeny in your answer.

(b) And, is MERS-CoV more closely related to Human Coronavirus HKU1 (HCoV HKU1) or SARS-CoV-2? Explain your answer.

Species • 90% s SH • 70% s SH < 90% O SH <70% Severe acute respiratory syndrome-related coronavirus Viruses SARS-CoV BEKY72 SARS-CoV-2 IL SARSr-CoV RaTG13 SARS-CoV PC4-227 SARS-CoV Bat Hp-BetaCoV Ro-BatCoV GCCDC1 — Ro-BatCoV HKUS Ei-BatCoV C704 - Pi-BatCoV HKU5 Ty-BatCoV HKU4 MERS-CoV Ericov - Мну - HCOV HKU1 ChRCOV HKU24 — HCOV OC43 - MrufCoV 2JL14 -HCOV NL63 -HCOV 229E Bat Hp-betacoronavirus Zhejiang 2013 Rousettus bat coronavirus GCCDC1 Rousettus bat coronavirus HKU9 Eidolon bat coronavirus C704* Pipistrellus bat coronavirus HKU5 Tylonycteris bat coronavirus HKU4 Middle East respiratory syndrome-related coronavirus Hedgehog coronavirus 1 Murine coronavirus Human coronavirus HKU1 China Rattus coronavirus HKU24 Betacoronavirus 1 Myodes coronavirus 2JL14* Human coronavirus NL63 Human coronavirus 229E 0.1 Source: Coronaviridae Study Group of the International Committee on Taxonomy of Viruses, Nature Microbiology. March 2020. The phylogeny above shows relationships between different coronaviruses, including common human respiratory viruses (orange), zoonotic viruses that are pathogenic in humans (purple), and other coronaviruses that are generally not pathogenic in humans (black).