Viral, host and environmental factors that favor anthropozoonotic spillover of coronaviruses: An opinionated review, focusing on SARS-CoV, MERS-CoV and SARS-CoV-2

Abstract

Environmental factors play a key role in the zoonotic transmission of emerging pathogenic viruses as mankind is constantly disturbing wildlife's ecosystems usually by cutting down forests to build human settlements or by catching wild animals for food, which deprives the viruses of their natural hosts and gives them opportunity to infect humans. In December 2019, a new coronavirus emerged from bats and was named SARS-CoV-2 by the International Committee for Taxonomy of Viruses, and the disease it causes named COVID-19 by the World Health Organization. Disease outbreaks such as SARS in 2002–2003, MERS in 2012 and the current COVID-19 pandemic are the result of higher mutation rates of coronaviruses and their unique capacity for genetic recombination, resulting in adaptations that make them more suitable to cross the species barriers and infect other species. This ability for host switching and interspecies infection is often attributed to the great diversity of these viruses, which is a result of viral and host factors such as the low fidelity of their RNA-dependent RNA polymerase, the high frequency of their homologous RNA recombination, and the adaptation of the S protein to bind host receptors like the angiotensin converting enzyme 2 (ACE2) in the case of SARS-CoV and SARS-CoV-2, and dipeptidyl peptidase 4 (DDP4) in MERS-CoV. This review presents an overview of the zoonotic transmission of SARS, MERS and COVID-19, focusing on the viral, host and environmental factors that favor the spillover of these viruses into humans, as well as the biological and ecological factors that make bats the perfect animal reservoir of infection for these viruses.

Anti-Inflammatory, Antiallergic, and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus terreus

“…The co-crystalized ligand is known to form a hydrogen bond with Ser195 that is important for binding [36]. In this study, we have docked the isolated compounds (1)(2)(3)(4) in the active site of the human NE. Out of the tested compounds, only butyrolactone I (1) has shown a docking score superior to that of the cocrystalized ligand (Table 3).…”

“…For more than a year now, since 2019, the whole world has been faced with the Coronavirus Disease 2019 (COVID-19) pandemic, believed to be caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV 2), a zoonotic viral infection that first emerged and was reported in Wuhan, China in December 2019 [ 1 , 2 ]. During this year, scientists from all around the globe set new horizons for collaborations to race against time to produce a dependable and a reliable vaccine.…”

The Safety of Slaughterhouse Workers during the Pandemic Crisis

“…Besides the viruses mentioned above, there is also the class of Coronaviridae that is further divided into four genera: alphacoronavirus, betacoronavirus, gammacoronavirus, and deltacoronavirus, however, it was found that only alpha- and betacoronaviruses are infectious for humans [ 15 , 16 ]. Coronaviruses are endemic, and most of the strains cause common colds, but some of the strains provoke severe lower respiratory tract infections, and might be lethal [ 17 , 18 , 19 , 20 ].…”

Emerging and Re-Emerging Diseases: Novel Challenges in Today’s World or More of the Same?

“…Emerging (and re-emerging) transmissible diseases have been impacting human populations since the Agricultural revolution, when hunter-gatherers settled and started crop cultivation and animal domestication, circa 12,000 years ago, reflecting man’s first steps in nature’s manipulation [ 3 , 4 ]. Since then, a vast number of animal and human diseases have circulated on the earth’s surface [ 4 ], reaching to the current 2019 novel coronavirus epidemic as an extreme reminder of the role animal reservoirs play in public health [ 5 ], shedding SARS-CoV-2 to humans where it adapted and became transmissible by air [ 6 ] and surfaces [ 7 ].…”