VIRUSES: Structure and Properties Viruses consist of particles containing a nucleic acid (rna or DNA), which encodes all the information necessary for multiplication in the correct environment(host) The nucleic acid constitutes the viral genome and is associated with protein to form a nucleocapsid Depending on the presence or absence of lipid in the membrane viruses are termed enveloped or nonenveloped, respectively
VIRUSES: Structure and Properties • Viruses consist of particles containing a nucleic acid (RNA or DNA), which encodes all the information necessary for multiplication in the correct environment (host). • The nucleic acid constitutes the viral genome and is associated with protein to form a nucleocapsid. • Depending on the presence or absence of lipid in the membrane, viruses are termed enveloped or nonenveloped, respectively
Viruses: Structure Enveloped Nonenveloped Adopted from PD Minor, 2000
Viruses: Structure Enveloped Nonenveloped Adopted from PD Minor, 2000
Viruses: Structure Surface proteins Nucleocapsid Protein she Nucleic acid Nucleic acid Lipid layer Membrane(matrix TOrO protein) Viruses contain a few proteins, lipids and nucleic acid which are accurately replicated by the infected cell to give more virus
Viruses: Structure • Viruses contain a few proteins, lipids and nucleic acid which are accurately replicated by the infected cell to give more virus
Spread to other cells Cell Spread to new host Attachment to Transport to infectable receptors Uncoating in specific cell compartment Location Cell of next cell Nucleus entry 十1十 Takeover of Virus release cell machinery Replication of genome mRNA synthesis Protein synthesis ssembly of components Assembly of particle Packaging of genome Transport to cell surface avoidance of cell death
The virus life cycle Viral genome is encased in a package composed of proteins usually encoded by the nucleic acid, and serving the functions of preserving the genome until a new host is reached, and delivering it to the right site such as poliovirus, are able to survive passage through the nigh cs Protecting the genome while it is in the environment- Enterovirus acidity of the stomach and infect the intestine, while closely related viruses such as the rhinoviruses are not The delivery system of the virion requires the recognition of a cell as a likely target, and this frequently involves a specific interaction between the virus and a particular cell surface molecule
The virus life cycle • Viral genome is encased in a package composed of proteins usually encoded by the nucleic acid, and serving the functions of preserving the genome until a new host is reached, and delivering it to the right site. • Protecting the genome while it is in the environment – Enteroviruses, such as poliovirus, are able to survive passage through the high acidity of the stomach and infect the intestine, while closely related viruses such as the rhinoviruses are not. • The delivery system of the virion requires the recognition of a cell as a likely target, and this frequently involves a specific interaction between the virus and a particular cell surface molecule