Moroccan Journal Of Public Health Vol. 1, N° 1 (2020), 52-63 ISSN: 2658-8099 Review Comparative Epidemiology of Coronavirus Infections in humans and animals Mohamed Mahi FASSI-FEHRIa and Ouafaa FASSI FIHRIa* Microbiology, Immunology and Contagious Diseases,Institut agronomique et vétérinaire AV Hassan II, Rabat. Corresponding Author Email: Ouafae FassiFihri: [email protected] Article info SUMMARY Received June 2020 Coronaviruses are a group of RNA viruses that cause diseases in mammals and Accepted September 2020 Online September 2020 birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold, which can also be caused by other viruses, predominantly Keywords rhinoviruses, while more lethal varieties cause Severe Acute Respiratory epidemiology, coronavirus, pathogenicity, evolution, Syndrome (SARS), Middle East Respiratory Syndrome (MERS), or the current characteristics. pandemic Coronavirus disease 2019 (COVID-19). In cows and pigs Coronaviruses cause diarrhea like the transmissible gastroenteritis virus (TGEV), while in young calves, the Bovine Coronavirus (BCV) causes severe profuse enteritis. In this review we will go over the microbiology of coronaviruses, their classifications and the different infections caused by it in animals and humans. various fields joined the urgent fight against this deadly Introduction Since December 2019, the world has been confronted disease. In the light of preliminary observations and with the torments of an emerging pandemic, designated raised questions, it is interesting to carry out a by the name of COVID-19, which stands for comparative study on the coronaviruses involved in Coronavirus Disease-19. It is caused by the Severe acute human and animal infections, which could contribute in respiratory syndrome coronavirus 2 (SARS-CoV-2) understanding the natural and spontaneous models. In (WHO, 2020). Health, social, economic and this review we will be covering the morphological, environmental consequences of the pandemic, in the structural and biological characteristics of the short and medium term, seem immeasurable. The global coronaviruses and their nomenclature and classification. battle against the virus continues up to this date. With no Then we will go over some pathologies caused by drugs or treatments in the market, researchers from 52 Moroccan Journal Of Public Health Vol. 1, N° 1, (2020) 52-63 coronaviruses in animals. Finally we will go over the noticeable infections caused by the coronaviruses over the years in humans. We will briefly summarize the 2003 Severe acute respiratory syndrome coronavirus (SARS- CoV) epidemic, followed by the 2012 Middle East Respiratory Syndrome (MERS) and then the recent outbreak of the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019. 1. Morphological, structural and biological Photo 1. Coronavirus in negative contrast electron characteristics of Coronaviruses microscopy (Image courtesy of Dr L. Kolesnikova, 1.1. Morphology Institute of Virology, Marburg, Germany) Coronaviruses are presented in negative contrast electron 1.1. The structural characteristics of viral particles 1.1.1. Viral proteins Virions are composed of structural and non-structural proteins. The S protein assembles into trimers on the virion surface and is responsible for attachment of particles to host cellular receptors and fusion of viral envelope with the host cell membrane, a process that involves mechanisms of translation, fusion and recombination of the surface, which results in an intracellular penetration of the virion (Hofmann and Pöhlmann, 2004). Protein S undergoes large microscopy as spherical or polymorphic particles, conformational rearrangements during the viral envelope presenting an envelope of 60 to 220 nm in diameter. fusion with the cell membrane (Fehr et al., 2015). Most Club-shaped surface projections (12 to 24 nm long), the Coronaviruses depend on host cellular proteases for their spicules (S) or spikes, protrude from the envelope, giving entry into cells. Protein S induces the synthesis of it the crown appearance, hence the latin name corona neutralizing antibodies. It is a major Coronavirus antigen (Stadler et al., 2003) (photo 1). An empty space separates with several domains; the S1 domain containing most of the viral core, constituted by the helical nucleocapsid, the epitopes recognized by neutralizing antibodies during from the envelope (Photo 1). an infection. The M protein integrated into the membrane is essential for encapsidation. Other major components include The nucleocapsid (N) proteins, the envelope (E) protein and hemagglutinin esterase (Schoeman and Fielding, 2019), and the non-structural 53 Moroccan Journal Of Public Health Vol. 1, N° 1 (2020) 52-63 proteins that are not required for viral replication: e.g. Orthocoronavirinae. Coronavirus contains 4 genra: ⍺, replicase, NSP1, 2, 3...up to14 (Angelini et al., 2013). β, Ɣ and δ coronavirus. The alpha-Coronavirus genus 1.1.1. Coronavirus Genome includes Porcine, feline and canine Coronaviruses. The coronavirus genome is a single-stranded positive- Viruses isolated from bats, The beta-coronavirus genus, sense RNA, ranging from 26 to 32 Kb in length. It is include viruses involved in seasonal human diseases, capped at the 5' end and has a 3′ poly (A) tail. It is an viruses responsible for epidemics and pandemics of infectious mRNA molecule whose function is to initiate human SARS, Bovine disease viruses and viruses mRNAs for protein synthesis necessary for infection isolated from bats. Lastly, the gamma and delta- (Snijder et al., 2003). coronavirus genera include viruses responsible for avian 1.2. Viral replication disease and viruses of migratory birds. Tables 1 2 and 3 list the main animal and human Coronavirus diseases, as The viral replication of the coronaviruses includes well as the list of virus reservoir host animals. several steps. It begins by the recognition and attachment to target cells by S glycoproteins. There are many types Table 1. Inventory of major coronavirus of cellular receptors, namely the aminopeptidase for diseases (Saif, 2004) Porcine transmissible gastro-enteritis virus (TGEV) Porcine diseases (alpha-coronavirus) (Bin Wang et al., 2018) and Human coronavirus 229E Porcine transmissible gastroenteritis (1945) (H229E) (Jamie et al., 2003), feline or canine Porcine respiratory disease (1970) aminopeptidase N and carcinoembryonic antigen Porcine epidemic diarrhea (1970) (Tresnan et al., 1996). After attachment, a protease of Bovine diseases (beta-coronavirus) the host cell cleaves and activates the receptor-attached Bovine pneumo-enteritis spike protein. After the entry to the host cell, the virus is Calf enteritis uncoated and its genome enters the cell's cytoplasm. Avian diseases (gamma-coronavirus) Translation of the positive-strand genomic RNA gives Avian infectious bronchitis (1937) Coronaviral enteritis of turkeys rise to a large polyprotein that undergoes proteolytic processing to generate an RNA-dependent RNA Other affected species (alpha-coronavirus) Feline infectious peritonitis polymerase. RNA polymerase then generates an Canine enteric coronavirus antisense negative-strand template (Sethna et al., 1991). 1. Etymology and classification According to the International Committee of Taxonomy of Viruses report (ICTV, 2018), Coronaviruses belong to Order : Nidovirales, Family : Coronaviridae, Subfamily : 54 Moroccan Journal Of Public Health Vol. 1, N° 1 (2020) 52-63 Table 2. Inventory of the main human coronavirus diseases (Corman et al., 2018; Cui et al., 2019) Coronavirus encephalitis 229E and NL-63 (alpha-coronavirus) Coronavirus enteritis in children (alpha-coronavirus) Seasonal upper respiratory tract infections (OC-43, B-14, HKU1, NL-63) (beta- coronavirus) Epidemics and pandemics of severe acute respiratory syndrome (SARS) (beta- coronavirus) including : ✓ SARS-CoV 2002-2003 ✓ MERS-CoV 2012 ✓ SARS-CoV 2019 Table 3. Coronaviruses isolated from virus-reservoir host animals (Zhengli and Zhihong, 2008) Coronavirus of palm civet cats (Paguma larvata) Coronavirus of raccoon dog (Nyctereutes procyonoides) Coronavirus of pangolin (Manis javanica) Coronaviruses isolated from bats (Pipistrellus, Rousettus, Rhinolophus, Miniopterus) ✓ SARSr-CoV (W1V1) ✓ SARSr-CoV (HK 43) ✓ SARSr-CoV (RP3) ✓ HKU4 and HKU5 2. Coronaviruses in animal pathology 1960, were found in benign seasonal, endemic, respiratory (colds, rhinitis, laryngitis) (Kahn and Coronaviruses are associated with a wide range of McIntosh, 2005) or enteric infections, in humans and in enteric, respiratory and systemic infections in several many domestic (cattle, pigs, dogs, cats, etc...) or wild species of domestic and wild animals with varying (rodents, ferrets, hamsters, etc...) animal species. The degrees of severity. The first studies concerning animal human Coronaviruses HCoV-229E, HCoV43, HCoV infections with Coronaviruses were those of the avian NL63 and HKU1 have been detected in various infectious bronchitis or porcine transmissible countries, indicating a worldwide distribution of these gastroenteritis, whose viruses were identified in 1937 viruses that are well adapted to humans and do not and 1945 respectively (Beaudette and Hudson, 1937; appear to be maintained by an animal reservoir (Hamre Cheever et al., 1949). However, viral strains identified in and Procknow, 1966; Kahn and McIntosh, 2005). Since 55 Moroccan Journal Of Public Health Vol. 1, N°