bio 226 ch. 13 + 14 (viruses and INF)

what are some features of viruses?

• intracellular parasites

• no binary fission

• have DNA/ RNA

• protein coat (NO membrane)

why are viruses considered intracellular organisms?

they need a host to survive and multiply

• uses host’s proteins and machinery (ATP) to make next gen

• no ribosomes or ATP making machinery

what is the spectrum of hosts a virus can infect called?

host range

• most viruses infect specific parts in a host’s cells

what is a bacteriophage? what does it do specifically?

evil larry; virus that infects bacteria

• attach to phage receptors (may be on cell wall, fimbriae, or flagella)

what are the parts of a bacteriophage?

a fully developed viral particle? what is this particle made of?

virion

• made of DNA/ RNA, single/ double stranded; linear/ circular/ segmented

what are some parts of a virus? why are they important?

• capsid - protein coat made of capsomeres (subunits) 

• envelope - lipid, protein, and carbohydrate coating (some)

  • part is formed when virus buds from host membrane

• spikes - attachment/ recognition + decoration :)

can a viral genome have DNA or RNA?

one or the other; NEVER BOTH (1K - 250K nucleotides)

describe a helical virus

hollow with a cylindrical capsid

what is a virus with many sides called?

polyhedral virus

what is the main component/ part of an enveloped virus?

an outer lipid membrane (usually obtained from departure of host cell)

what is a complex virus? give one example.

viruses with complex structures

• ex. evil larry 

what is the naming, classification, and relation to other organisms called?

taxonomy

what is the classification system that uses nucleic acids and mRNA formation to classify viruses?

Baltimore classification system

groups of viruses are also referred to as “___"?

realms

what is the genus name ending for viruses?

“- virus”

what is the family name ending for viruses?

“- viridae”

what is the order name ending for viruses?

“ - ales”

what is the term for a group of organisms sharing the same genetic info?

species

compare plaque forming units (PFU) and colony forming units (CFU)

• plaques are created from the lysis of bacteria on a plate after incubation

  • bacteriophages are diluted into a bacterial sample and then poured onto a plate

• colonies are formed from ONE bacterial cell on a plate after incubation

  • bacteria are inoculated onto plate

embroynated eggs are used for viral growth. how and why?

how: viruses are injected into egg

• visible changes or death of embryo = viral growth

why: this allows for the growth of viruses so vaccines can be made

• in some animals, viruses can’t be grown WHILE some can grow but cannot cause disease

describe the steps of the cytopathic effect

1st - tissues treated with enzymes → separates cells

2nd - cells suspended in nutrient solution = “primary cell line”

3rd - cells adhere to container + reproduce = monolayer

• visible changes/ deterioration of monolayer = viral infection

  • continuous source of cells needed

name some ways viruses are identified

• cytopathic effect on cells/ culture

• serological test - ELISA (anitbody interaction used to detect and identify viruses)

• nucleic acid - PCR

what are the steps to viral multiplication?

invasion → take over key host machinery →use machinery to replicate + mature

compare the lytic and lysogenic cycle

lytic - phage causes lysis of host

• attachment, penetration, biosynthesis, maturation, + release

lysogenic - phage DNA integrated into host DNA; phage conversion + specialized transduction

term for when a phage remains in a host cell but is immature/ inactive. what are some outcomes of this term?

lysogeny

• lysogenic cells are immune to infection of same phage

• phage conversion = cell exhibits phage’s properties

• specialized transduction (specific genes transferred to bacteria via evil larry

what is a prophage?

the inserted phage DNA; replicated w/ host cell DNA

what are the steps for the multiplication of animal viruses?

attachment → entry (receptor - mediated OR fusion) → uncoating → biosynthesis → maturation → release (budding)

where are the specific parts in a cell where viruses mature?

• DNA replicated in nucleus of host

• capsid synthesized in cytoplasm of host via RNA - dependent RNA polymerase

  • capsid proteins migrate to nucleus to continue assembly

what is positive and negative ssRNA? dsRNA?

• ssRNA: + sense strand → vRNA used as mRNA for protein synthesis

  • - sense strand → vRNA transcribed into mRNA for protein synthesis

• dsRNA - double stranded RNA

what’s the significance of a provirus?

provirus - DNA made from vRNA via reverse transcriptase; integrates into host DNA

• provirus DNA is protected from host’s immune system + antiviral drugs

cancer of connective tissues

sarcoma

cancer of glandular epithelial tissue

adenocarcinomas

what are genes that encode proteins that stimulate normal cell growth?

proto - oncogene

mutated proto - oncogenes make __?

oncogenes

• transfer normal cells into cancerous cells

when cells acquire new properties

transformation

what do oncogenic viruses do?

integrate into host DNA → induce tumors

when cells are transformed they carry __?

TSTA = tumor - specific transplantation antigens (on surface + irregularly shaped)

viruses that infect + kill tumor cells via immune response

oncolytic viruses

organism or virus carrying a pathogen but does not exhibit symptoms of said disease

asymptomatic 

what is a latent virus?

infection that is inactive inside a host cell for a long period of time

• can activate bc of immunity changes

fatal infection that gradually worsens

persistent viral infection

plants get viruses through wounds or insects but are generally protected by a impermeable cell wall

short pieces of naked/ exposed RNA

viroids

viroids enclosed in a protein coat

virusoids

a proteinaceous infectious particle

prion

• inherited + transmittable (ingestion, transplantation, and surgical tools)

  • ex. mad cow disease (prions in beef → ppl cooked or undercooked meat → ingested meat = disease)

PrP^c vs. PrP^sc

PrP^c - normal cellular prion protein; cell surface

PrP^sc - scapie protein; crowds brain cells = plaques; misfolded form (conversion of normal host glycoprotein)

study of disease

pathology

cause of disease

etiology

how a disease develops

pathogenesis

what is an infection?

invasion of pathogens in the body

when is an infection considered a disease?

when the infection changes the state of health

how early do humans establish a microbiome?

utero (in amniotic sac)

• placenta provides microbiome

what microbe is present in the placenta during fetal development?

enterbacteriaceae and propionibacterium

what microbe inhabits the neonate intestine AFTER vaginal birth only?

lactobacilli

development allows for more microbial collections (food, people, pets, etc.)

importance of microbes

help and contribute to health and disease

• around 4 × 10¹³ 

what is the relationship between microbial communities and the body/ human health called?

human microbiome project

microbes that are a part of the human microbiome, is permanent, and do not cause disease?

normal microbiota

microbes that are only temporary in the human microbiome?

transient microbiota

the distribution and composition of the human microbiome is important and a staple to the immune system (controlled by many factors)

compare vaginal birth and c- section birth

vaginal - gives lactobacillus and bacterioides

c- section - give only microbes that resemble human skin + staphylococcus aureus

the term for when microbes compete with each other

microbial antagonism/ competitive exclusion

• normal microbiota compete w/ foreign microbes for nutrients, produce harmful substances, and affect pH and oxygen levels

give an example of a antagonistic microbe

Clostridium difficile causes intestinal infections when normal microbiota are depleted (via antibiotics)

• may call for a fecal microbiota transfer (FTM) → replaces normal microbiota

symbiosis

relationship between two organisms; at least one benefits

when one organism benefits while the other does not

parasitism

when both organisms benefit

mutualism

when one organism benefits while the other isn’t effected

commensalism

microbes that exist without affecting the host but cause disease when host immune system is weakened

opportunistic microbiota

how does Koch’s postulates relate to microbiology?

Koch discovered a causitive microbe always has the same symptoms, even in different (but susceptible) hosts

what is the criteria for Koch’s postulates?

• said pathogen must be present in every case of said disease

• pathogen must be separated from host and grown in culture

• pathogen cultured must cause same disease when inoculated into healthy host

• pathogen must be isolated from inoculated organism and be proven it is the original pathogen

symptoms

subjective changes in the body; anything felt by the patient

signs 

objective (observable/ measurable) changes in the body

specific group of signs and symptoms that accompany a disease

syndrome

term for a disease that spreads from host to host vs. term for a disease that is spread faster and easier (most likely a group transfer)

communicable disease vs. contagious disease

a disease that IS NOT spread

noncommunicable disease

incidence

the # of ppl who DEVELOP a disease during a specific time

prevalence

the # of ppl who HAVE a disease during a specific time

sporadic disease

disease that comes and goes

endemic disease

disease constantly present in a population

disease acquired by many ppl in a given area (short period of time)

epidemic disease

worldwide disease

pandemic

average time individuals have a disease (diagnosis →cure/ death)

duration

acute disease

symptoms develop quickly; last for a short time

symptoms develop gradually; last longer amounts of time

chronic disease

subacute disease

between acute and chronic disease

term for an agent that is inactive for some time but causes disease upon changes in immunity

latent disease

immunity in most of a population

herd immunity

the presence and extensiveness of disease in the body AND ability to cause death

severity

• asymptomatic→mild→moderate→severe→critical→sepsis

infection fatality ratio (IFR)

# of deaths DIVIDED BY total # of infected in a specific time frame

case fatality ratio

proportion of individuals diagnosed w/ a disease who die within a time frame

• relationship between # of diagnosis and # of deaths

infections that are limited to a small area of the body

local infection

systemic (generalized) infection

infection spreads through body via blood + lymph

systemic infection that began as a local infection

focal infection

toxic inflammatory condition from the spread of microbes

sepsis

bacteria in the blood

bacteremia

toxins in the blood

toxemia

viruses in the blood

viremia

acute infection that causes initial illness

primary infection

opportunistic infection after primary infection

secondary infection