Virus

• Viral genomes can be single-stranded (ss) or double-stranded (ds).
• The viral genome is composed of nucleic acid, either DNA or RNA.
• Viruses are obligate intracellular parasites that require living cells to replicate.
• Bacteriophages, or phages, are viruses that infect bacteria.
• DNA viruses have nucleic acid genomes made of DNA, while RNA viruses have RNA genomes.
• what is enveloped viruses@
• Enveloped viruses have an outer membrane derived from the host cell's plasma membrane.
• Viral classification can be based on:
• Viral classification can be based on

  genome structure and core, capsid structure, type of mRNA produced and type of host
• Types of viral hosts?

  Animal, plant and bacteriophages
• What is zoonoses?

  Infection diseases that can be transmitted from animals to humans
• Types of plant viruses?

  Tobacco mosaic virus, Potato virus Y, Tomato spotted wilt virus, Citrus tristeza virus, etc.
• Bacteriophage hosts and viruses?

  E.coli                                       T4 bacteriophage

   E.coli                                        λ  bacteriophage

   Listeria monocytogenes                  Caudovirales
• Viruses may be named based on?

  Host, symptoms, or characteristics
• Stages of viral infection?

  Attachment, penetration, replication, assembly, release.
• What are the stages of attachment?

  The virus attaches to host cell, T4 phage tail attaches to host then the virus attaches to receptors on host cell.
• Types of penetration?

  Direct, Endocytosis and Membrane fusion.
• Direct penetration?


  The virus bind to specific receptors (proteins) on the surface of the host cell, followed by the injection of genetic materials.
• Membrane fusion?

  •The virus binds to specific receptors on the host cell •The envelop of the virus then fuses with the host cell membrane•The viral capsid enters the host cell•This is then followed by the ‘uncoating’ of the viral capsid•
• Endocytosis?


  •The viral envelop binds to specific receptors on the surface of the host cells• The host cell then internalises/engulfs the whole virus• Degradation of the lipid envelop and ‘uncoating’ follows that results in the release of viral genome into the host
• what happens during uncoating?

  Separation of viral nucleic acid from the protein coat.