Morphology
Coronavirus particles are irregular in shape, about 60-220nm in diameter. Virus particles wrap the fatty membrane, and there are three glycoproteins on the membrane surface: Spike Protein (S, Spike Protein, which is the receptor binding site, cytolysis and main antigen site); Small Envelope Glycoprotein (E, Envelope Protein) Protein, a small protein that binds to the envelope); Membrane Protein (M, Membrane Protein, is responsible for the transportation of nutrients across the membrane, the budding release of new viruses, and the formation of the virus envelope). A few species also have hemagglutinin glycoprotein (HE protein, Haemaglutinin-esterase). The nucleic acid of coronavirus is a non-segmented single-stranded (+) RNA with a length of 27-31kb. It is the longest RNA nucleic acid strand in RNA viruses. It has an important structural feature unique to positive-stranded RNA: that is, the 5'end of the RNA strand is methylated. "Hat", the 3'end has a PolyA "tail" structure. This structure is very similar to eukaryotic mRNA, and it is also an important structural basis for its genomic RNA itself to function as a translation template, eliminating the RNA-DNA-RNA transcription process. Coronavirus has a very high recombination rate between RNA and RNA, and the mutation of the virus is due to this high recombination rate. After recombination, the RNA sequence has changed, and the amino acid sequence encoded by the nucleic acid has also changed, and the protein composed of amino acids has changed accordingly, and its antigenicity has changed. The result of the change in antigenicity is the failure of the original vaccine and the failure of immunity.
Viral RNA polymerase, which is required for RNA virus replication, does not exist in the mature particles of coronavirus. After entering the host cell, it directly uses viral genome RNA as a translation template to express viral RNA polymerase. Then use this enzyme to complete the transcription synthesis of negative-strand sub-genomic RNA (sub-genomic RNA), the synthesis of various structural protein mRNA, and the replication of viral genomic RNA. The mature mRNA synthesis of each structural protein of coronavirus does not have a post-transcriptional modification and shearing process, but directly through RNA polymerase and some transcription factors, using a "discontinuous transcription" mechanism, by identifying specific, TRS) , Selectively transcribe all the components of a mature mRNA from the negative sense strand RNA at one time. After the structural protein and genomic RNA have been replicated, they will be assembled at the endoplasmic reticulum of the host cell to generate new coronavirus particles, which will be secreted out of the cell through the Golgi apparatus to complete their life cycle.

Classification
Coronavirus belongs to the order Nidovirales, Coronaviridae, and Coronavirus. It is an important pathogen of many domestic animals, pets, including human diseases, and causes a variety of acute and chronic diseases. According to the phylogenetic tree, coronaviruses can be divided into four genera: α, β, γ, and δ, among which β genus coronaviruses can be divided into four independent subgroups A, B, C, and D.
Alpha-coronaviruses include 8 species including human coronavirus 229E, human coronavirus NL63, long-winged bat coronavirus HKU1, long-winged bat coronavirus HKU8, chrysanthemum bat coronavirus HKU2, and porcine epidemic diarrhea virus (Porcineepidemic diarrheavirus, PEDV). , Transmissible gastroenteritis virus (Transmissiblegastroenteritisvirus, TGEV), canine coronavirus (Caninecoronavirus, CCoV) and feline coronavirus (Felinecoronavirus, FCoV).
Beta-coronaviruses include 7 species including human coronavirus HKU1, murine coronavirus, house bat coronavirus HKU5, fruit bat coronavirus HKU9, severe acute respiratory syndrome (severeacuterespiratorysyndromes, SARS)-related viruses, and bovine coronavirus (Bovinecoronavirus, BCoV). ), human coronavirus OC43, equine coronavirus (Equlnecoronavirus, ECoV), porcine hemagglutinatingencephalomyelitis (PHEV) and canine respiratory coronavirus (CrCoV), etc.; murine coronavirus includes murine hepatitis Virus (Mousehepatitisvirus, MHV), rat coronavirus and bird's beak puffin virus. Severe Acute Respiratory Syndrome (SARS) related viruses include SARS virus and other similar SARS viruses.
γ-type coronaviruses mainly include avian coronaviruses such as Infectious bronchitis virus (IBV) and Beluga whale coronavirus SW1 (Beluga whale coronavirus SW1, BWCoV-SW1). Avian coronaviruses include coronaviruses that cause infections of many birds, such as chickens, turkeys, sparrows, ducks, geese, and pigeons, the most important of which is avian infectious bronchitis virus.
Coronavirus of the δ genus includes Nightingale coronavirus (Bulbul coronavirus HKU11, BuCoV HKU11), Thrush coronavirus (Thrush coronavirus HKU12, ThCoV HKU12), Munnia Coronavirus (Thrush coronavirus HKU12, ThCoV HKU12), Asian Leopard Coronavirus "Asian Leopard" Cats Coronavirus, ALCCoV), Chinese ferret-badger Coronavirus (CFBCoV), Por-cine Delatcoronavirus (PDCoV), White-eye Coronavirus (WECoV), Sparrow Coronavirus (Sparrow Coronavirus, SPCoV), Magpie robin Coronavirus (MRCoV), Night Heron Coronavirus (Night heron Coronavirus, NHCoV), Wild Duck Coronavirus (Wigeon Coronavirus, WiCoV), Blackwater Chicken Coronavirus (Common Moorhen Coronavirus, CMCoV).
Although the first coronavirus was discovered in the 1930s, the coronavirus really attracted attention when the SARS coronavirus (SARS-CoV) caused the SARS epidemic in 2002-2003, which spread to many countries and regions, causing After the social panic. Prior to this, research on coronaviruses was mostly restricted to the field of veterinary medicine. Infectious bronchitis caused by IBV of the γ genus is highly contagious in chickens and is one of the important respiratory diseases, which is very harmful to the poultry breeding industry.

About Us
Creative Biostructure is dedicated to providing professional contract services to academia and biotechnology/pharmaceutical industries in the fields of structural biology and membrane protein technology. Here are some our services: Coronavirus preclinical research service, SARS-CoV-2 Contract Research Service, COVID-19 Contract Research Service, Coronavirus bioinformatics analysis, etc.