A tale of the ravaging ‘crown’ virus
Dr Ebenezer Idowu Ajayi
Wednesday, 15 April 2020
The new coronavirus, SARS-CoV-2, causing the respiratory disease known as COVID-19, belongs to family of the coronaviruses, and has its Ribonucleic Acid (RNA) core enveloped by fatty acids carrying spike glycoproteins on the surface forming a resemblance of a crown, called "corona" in Latin and other related Romance languages such as Spanish.
This class of virus causes infections in humans. It has been speculated to have been transmitted from the bat, the popular natural host, to either the pig (extending to the hog) or to the pangolin and then to humans, beginning from the Huanan wet market in Wuhan, Hubei Province of China. Although it was earlier considered that humans cannot infect other animals (especially pets) nor be transmitted by them, there is now a first case of a 4-year old Malayan tiger, Nadia confirmed to have been infected among the 7 sick big cats at the Bronx zoo, New York after it developed dry cough following contact with her infected caregiver, an asymptomatic zookeeper. Her test came out positive for COVID-19 on April 5, 2020.
The possibility of mutation of this virus may make it highly infectious for animals and may cause worries among animal handlers and pet owners or those near them. About 40 strains of the virus have been profiled, and it appears that the gain-of-function especially in the S-protein and probably of the envelope M-protein of the original bat coronavirus might have now rendered them able to exert cross-species infection via the ACE-2 receptor. Naturally, part of the virus life cycle is that its RNA makes contact with a host and replicates itself using the cell machinery of the host. Interestingly, the coronavirus, SARS-CoV-2, appears to be mutating at a very slow, unaggressive pace. The structural characteristics and infection mechanism are also a near fit to the original strain, thus making drug or vaccine design a hopeful effort at this stage and period of time.
Diverse pieces of evidence are being reported as to how asymptomatic persons lose their sense of smell (anosmia), voice; able to disperse it in their breath (micro-droplets especially from forced breath in those with underlying respiratory distress), fart and excreta. Scanty research findings have also suggested the ability of the virus to cross the blood-brain barrier to cause a nervous breakdown. All of these claims need further investigation in order to gather robust evidence before they can be acceptable. While the scientific community rally round and continue to work hard towards a problem-solving consensus to find a lasting cure for this public health challenge, let us all endeavor to stay safe, and be weary of speculations as they can be misleading.
As at the time of writing this global tale (April 16), there are 34 countries with more than 5000 cases with community spread. It suffices to say that if we do not heed the medical advice as necessarily put in place to flatten the curve, more dead bodies of casualties than can be handled for disposal would mean more contamination through the body fluids that would exude from them. Our health front line workers are already in danger of coming in contact with viremic (circulating in the blood of) a/symptomatic patients that are reporting for testing. We should cooperate in order not to overwhelm the system.
So far, compared to blood test, using the nasopharyngeal swab is the best way to confirm the infection, as this is more representative of the route of infection and manifestation of symptoms including dry cough and production of copious mucus that has the capacity to block the airway. The fact remains that there is need for expanded testing in order to know how many people have really been infected.
Therefore, until it is scientifically ascertained in a convincing manner that other animals can be infected, serve as a reservoir for the virus or capable of transmitting the virus to other animals and humans; and whether or not the virus may be shed in the excreta of a/symptomatic hosts, it will be imperative to continue to follow the existing advice on handwashing, sneezing/coughing into the sleeves, washing clothing materials and shoes after returning home, not touching the face (especially the mouth, eyes, and nose) with unwashed hands, using alcohol-based sanitizers, nose masks and face masks, maintaining 2-meter space between persons, avoiding overcrowded spaces, practicing physical/body distancing, and ultimately staying at home.
Beyond every one's cooperation to flatten the curve, it is our responsibility to keep our environment free of coronavirus disease.
Ebenezer Idowu O. Ajayi Ph.D., FIPMD
Biochemistry Department, Osun State University, Osogbo, Nigeria
Instituto de Investigación Médica Mercedes y Martín Ferreyra - INIMEC-CONICET-UNC, Cordoba, Argentina
The views expressed in this article are the author`s own and do not necessarily reflect the editorial views of the Science Communication Hub Nigeria.
Ather B, Edemekong PF. Airborne Precautions. Treasure Island (FL): StatPearls Publishing. 2020.
Bauchner H, Fontanarosa PB, Livingston EH. Conserving Supply of Personal Protective Equipment—A Call for Ideas. JAMA. 2020. doi:10.1001/jama.2020.4770
Chan JF-W, Yuan S, Kok K-H, To K K-W, Chu H, Yang J, et al. A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. The Lancet. 2020; 395(10223): P514-523.
Daly N, NatGeo. Tiger tests positive for coronavirus at Bronx Zoo, first known case in the world. 2020.
Ghert-Zand R, The Times of Israel. Forensic pathologists beware: COVID-19 lives on in blood after death. 2020.
Greaves CD, Sanderson R, Tindale WB. Air contamination following aerosol ventilation in the gamma camera room. Nucl Med Commun. 1995; 16(11): 901-904.
LaMotte S, CNN. Loss of smell from coronavirus: How to test your sense. 2020.
Livingston E, Desai A, Berkwits M. Sourcing personal protective equipment during the COVID-19 pandemic. JAMA. 2020. doi:10.1001/jama.2020.5317
Mackenzie JS, Smith DW. COVID-19: a novel zoonotic disease caused by a coronavirus from China: what we know and what we don't. Microbiol Aust. 2020; MA20013.
PRO/AH/EDR COVID-19 Update (106): Global, WHO. Archive Number: 20200415.7228978.
Qian H, Zheng X. Ventilation control for airborne transmission of human exhaled bio-aerosols in buildings. J Thorac Dis. 2018; 10(Suppl 19): S2295–S2304.
Qiu J, Scientific American. How China’s “Bat Woman” Hunted Down Viruses from SARS to the New Coronavirus. 2020.
Song F, Shi N, Shan F, et al. Emerging coronavirus 2019-nCoV pneumonia. Radiology 295(1): 210–217.
Sun Z, Thilakavathy K, Kumar SS, He G, Liu SV. Potential factors influencing repeated SARS outbreaks in China. Int. J. Environ. Res. Public Health 2020, 17(5), 1633: 1-11.
Tellier, R., Li, Y., Cowling, B.J. et al. Recognition of aerosol transmission of infectious agents: a commentary. BMC Infect Dis 19, 101 (2019).
Wang Q, Zhang Y, Wu L, Niu S, Song C, et al. Structural and functional basis of SARS-CoV-2 entry by using human ACE2. Cell 2020 (In Press).
World Health Organisation. 2020. Laboratory biosafety guidance related to coronavirus disease 2019 (COVID-19). Interim Guidance.