Infectious Disease: Bacteria, Viruses, and Viral Replication

Infectious Disease Society Lecture 1

What is the ultimate focus of infectious disease?

The living cell of your body

What nucleic acids do bacteria contain?

Both RNA and DNA

How do bacteria replicate?

By division (fission)

Are bacteria capable of independent metabolism and protein synthesis?

yes

Are bacteria susceptible to antibiotics?

yes

What is the function of bacterial flagella?

Locomotion

What is the role of bacterial ribosomes?

Factories for protein synthesis

What is an endotoxin?

Lipopolysaccharide in Gram-negative outer cell wall; structural component

What is an exotoxin?

A soluble protein secreted by bacteria; alters signaling, damages cells, and can paralyze

What nucleic acids do viruses contain?

DNA or RNA but never BOTH

Can viruses carry out independent metabolism or protein synthesis?

No, they are intracellular parasites

Are viruses susceptible to antibiotics?

No, but some are susceptible to antivirals

How do viruses replicate?

Viruses replicate by hijacking the host cell’s machinery to produce viral components, which are then assembled into new viruses.

What is a virion?

An infectious virus particle

What is a capsid?

protein coat surrounding a virus

What is the tegument?

The area between envelope & nucleocapsid containing viral proteins that aid infection

What happens if the envelope of an enveloped virus is removed?

It loses infectivity

Which viral symmetry looks like a spiral staircase?

Helical symmetry

Which viral symmetry is based on 5:3:2 geometry?

Icosahedral symmetry

List the 10 steps of viral replication in order.

Attachment → Adsorption → Uncoating → Transcription (early) → Translation (early proteins) → Genome replication → Transcription (late) → Translation (late proteins) → Assembly → Release

What is a productive infection?

High virus production; host cell killed within hours-days

What is a chronic persistent infection?

Low-level virus production; host cell survives long-term

What is a latent infection?

Will remain in host for a long period of time (comes and goes)

What is transformation?

Virus alters host cell phenotype; can cause immortalization or cancer