Chapter 4

viruses shapes

helical, polyhedral, complex

host range

the spectrum of cells that a virus can infect

The host range of a virus is determined by

attachment of spikes to receptors, host cells ability to support viral replication, virus need to replicate in cell

methods of animal virus cultivation (growing)

organisms grown on cell culture, using living animals, eggs

virus titer

concentration of virus

How is the virus titer determined?

by lysis of cells

viral identification methods

Serplpgical, PCR, and Propagation

Diffrence between animal virus and bacteriophage

Animal viruses go completely into cells and bacteriophage acts like a needle and injects the DNA

Stages of Animal Virus Replication

attachment, entry, uncoating, biosynthesis, maturation, release

Biosynthesis

Viral nucleic acid is replicated, and viral proteins, capsid and spike proteins, are made.

Types of viral infections

acute and persistent

acute

viral multiplication occurs and symptoms are seen

persistent viral infection

occurs gradually over a long period, is fatal

latnet infection (herpes)

virus is present but not active, has periods of inactivity

chronic infection

virus reproduction causes symptoms after a long period of infection

viruses can have which two phases

acute and latent

slow infection

transmissible agents multiply without resulting in disease symptoms until they cause a fatal infection

oncogenic viruses

can cause cancer

Transformation

changing of a normal cell into a cancerous cell

oncogene

cancer causing gene

protooncogene

a normal gene involved in normal cell growth

Prions

infectious proteins

Prions lack

nucleic acid

Prions cause

holes in the brain

Pathogens

Disease causing microorganisms

virulence factors

traits of a microbe that promote pathogenicity

infection

invasion and growth of pathogens in the body

disease

An abnormal state in which the body is not functioning normally

microbial antagonism

competition between microbes

normal microbiota uses microbial antagonism how

by preventing pathogens from causing infection

Symbiosis

two organisms living together

Three types of symbiosis

mutualism, commensalism, parasitism

Commensalism

grows on us, doesnt benefit us or harm us

Mutualism

both organisms benefit

Parasitism

One organism benefits and the other is harmed

Probiotics

contain live organism you ingest, benefit normal flora

Prebiotics

nondigestible carbs that act as food for normal flora

syndrome

a group of symptoms or signs that always accompanies a specific disease

communicable disease

a disease that is spread from one host to another directly or indirectly

sporadic

disease that occurs in a population

endemic

disease that is a specific population or location

Resivoir of infection

environment where disease causing pathogen is found on regular basis, can be human, animal or non-living (fomites)

Fomite

inanimate object

vehicle transmission

transmission by an inanimate reservoir (food, water, air)

droplet transmission

transmission via airborne droplets

fomite transmission

microorganisms transferred from an inanimate object (door, table, medical equipment)

vector transmission

transmission of an infectious agent by an insect, arthropod, or animal

Endotoxin

a toxin that is present inside a bacterial cell and is released when the cell disintegrates

Superantigens

cause an intense immune response due to release of cytokines from host cells