Coronavirus and respiratory outbreaks Flashcards
What is the genomic size range of Coronaviruses, making it the largest among RNA viruses?
26-32 kb
What is the unique structure that encapsulates the RNA genome of Coronaviruses?
Helical nucleocapsid
What are the three main structural proteins present in all Coronaviruses?
Spike (S), Envelope (E), Membrane (M)
What is the function of the Nucleocapsid (N) protein in Coronaviruses?
Binds to the RNA genome to form the helical nucleocapsid
Aside from its role in host cell binding, what is another important application of the Spike (S) protein?
Utilized in vaccine development
What is the function of the Membrane (M) protein in Coronaviruses?
Serves as a matrix protein embedded in the envelope, interacts with the nucleocapsid, and organizes CoV assembly
What is the name of the third glycoprotein present in some Coronaviruses, such as HCoV-OC43?
Hemagglutinin Esterase (HE)
What are the two activities associated with the HE protein in Coronaviruses?
Hemagglutination and acetylesterase activity
What is the postulated role of the acetylesterase activity of the HE protein?
Acts as a receptor-destroying enzyme by removing acetyl groups from O-acetylated sialic acid
What is the principle behind viral hemagglutination caused by some Coronaviruses?
Interaction between viral surface proteins and carbohydrate groups on erythrocyte membranes
How can hemagglutination be utilized in virology?
To determine the titers of some viruses
What type of RNA genome do Coronaviruses possess?
Single-stranded, positive-sense RNA
What are the three main gene categories in the genome of Coronaviruses?
Replicase genes, Structural protein genes, Accessory genes
What is the specific order of genes encoding for proteins in all Coronaviruses?
Pol-S-E-M-N-3’
What are Open Reading Frames (ORFs) in the context of the Coronavirus genome?
Sections that encode nonstructural proteins and the HE protein, translated from a single mRNA species
What is the receptor binding site for SARS-CoV and SARS-CoV-2 on host cells?
Angiotensin Converting Enzyme 2 (ACE-2) receptor
Where is the ACE-2 receptor primarily found in the human body?
Surface of cells in the respiratory tract, lungs, and other tissues
What role does the Spike (S) protein play in the interaction with the ACE-2 receptor?
Binds with high specificity, triggering fusion of the viral envelope with the host cell membrane
What is the first step in the replication cycle of Coronaviruses?
Attachment and entry into the host cell
Describe the process of attachment and entry of Coronaviruses into host cells.
Spike protein binds to the host cell receptor, followed by fusion with the host cell membrane and release of genetic material into the cytoplasm
What is the first viral protein translated after uncoating in the Coronavirus replication cycle?
RNA-dependent RNA polymerase (RdRp)
What are the two types of RNA synthesized during the replication of Coronaviruses?
Genomic RNA and Subgenomic RNA
What is the function of the genomic RNA in Coronavirus replication?
Used to make copies of the entire viral genome
What is the function of the subgenomic RNA in Coronavirus replication?
Encodes for various viral proteins
What cellular compartments are involved in the assembly of viral components in Coronavirus replication?
Endoplasmic reticulum and Golgi apparatus
Describe the formation of the helical nucleocapsid during Coronavirus assembly.
Newly synthesized genomic RNA interacts with the Nucleocapsid (N) protein
How are mature Coronavirus particles released from the host cell?
Through exocytosis
What is the preferred binding site of the Nucleocapsid (N) protein, and what process is it more closely associated with?
Within the leader RNA; transcription and translation phase