Chapter 6 BIOL 2460

acellular

does NOT have cell

viruses

viroids

virusoids

prions

viruses

infectious & acellular

intracellular parasite host

DNA/RNA (not both)

material surrounded by capsid

lack gene reproduction

invades host & hijack cellular machinery (virions produced)

transmission

host varies (cell type, species type, group of organisms)

bacteriophage (virus only infect bacteria)

infection obtained:

direct contact

fomite (eating, utensil, doorknobs, bedding)

mechanical vector (host carry virus outside of body) (cockroach)

biological vector (host carry virus inside of body (ticks, mosquitoes)

virus size

20 nm - 900 nm

virus shapes

capsid (protein coating surrounding material

helical (tobacco)

polyhedral (iscosahedral)

complex (variola)

virus structure

enveloped viruses - phospholipid surround capsid

naked viruses - capsid only

spikes - hemmagglutinin (H) or neuraminidase (N)

virus classification

family - viridae

genus - virus

not in tree of life

International Classification of Diseases (ICD)

clinically prescribed treatments

order lab tests

health-care management

phage life cycle

virulent phage - death to host cell thru lysis

temperate (latent) phage - become part of host til makes new virus (progeny virus)

lytic cycle of virulent phages

attachment

penetration

biosynthesis

maturation

lysis

generalized transduction

DNA random when transferred during lytic cycle

specialized transduction

occurs end of lysogenic cycle & transfer host DNA

specialized phage transduction

viral attachment & penetration

integration

excision

infection

recombination

viral life cycle eukaryotes

bind to host, animal virus enter via endocytosis or membrane fusion

host specific (tissue tropism)

ex.) poliovirus - brain & spinal cord tissue

influenza virus - respiratory tract tissue

viral life cycle eukaryotes

attachment

penetration

uncoating

release

assembly

biosynthesis

nucleic acid biosynthesis

double stranded DNA - normal flow of host cell

single stranded DNA - strand is synthesized then to normal flow

-double stranded RNA - acts like mRNA

+single stranded RNA - convert single strand RNA thru special RNA polymerase

RdRP = viral RNA-dependent RNA polymerase

retrovirus

reverse transcriptase enzyme to synthesize ssDNA (cDNA) from +ssRNA template

dsDNA in host chromosome

integrated viral genome (provirus)

bacteria (prophage)

provirus (virus)

latent infection

initial sign of infection then goes dormant

(herpes simplex virus)

chronic infection

host cannot kill off virus

(HIV chronic after latency period

viral plant life

most have +ssRNA genomes

in vivo

grown in organism

in vitro

grown outside organism

bacterial lawn

bacteriophages grown in dense layer of bacteria

4 phases of viral growth (bacteriophage)

inoculation - virus cause infection

eclipse - virus bind & penetrate (no virion detected)

burst - virions release from lysed host cell

bust size - number of virion released per bacterium

viral detection

effect on cells

hemagglutination assay

nucleic acid test

enzyme immunoassay

cytopathic effects (CPEs)

loos of adherence

change shape of cell

shrinkage of nucleus

vacuoles formed

fusion of cytoplasmic membranes form multiple nuclei

inclusion bodies

cell lysis (death)

nucleic acid amplification test (NAAT)

polymerase chain reaction for DNA

reverse transcriptase PCR for RNA

enzyme immunoassay (EIAs)

detect virus directly/indirectly through antigen/antibodies

viroids

virus like

circular RNA can self-replicate (no DNA conversion)

potato tuber spindle disease

virusoids

does NOT self-replicate ssRNAs

subviral particles

subterranean clover mottle virus

prions

misfolded rogue protein cause others to misfolded

ex.) mad cow disease

cause transmissible spongiform encephalopathy

transmitted between animal & from animal to human eating contaminated meat/feed

transmitted human to human through heredity

difficult to destroy, no treatment