Unit 3 - Viruses Flashcards
phage means what?
virus
Viruses can have DNA or ____?
RNA
Do viruses benefit the host cell?
No, they do not bring a benefit
Are viruses alive?
No
Where do viruses live?
Viruses live in cells, but are not cells
individual viruses are called what?
virions or particles
all viral genomes have some covering called what?
Capsid or Envelope
Is viral DNA single or double stranded?
Viral DNA can be both - single or double stranded
What’s the (+) RNA strand like?
mRNA
What’s the (-) RNA strand?
A template for (+) RNA strand
Pox
DNA or RNA virus?
Enveloped or nonenveloped virus?
Pox is an enveloped DNA virus
Herpes
DNA or RNA virus?
Enveloped or nonenveloped virus?
Single or double stranded?
Herpes is an enveloped DNA virus.
Double stranded.
Hepadma
DNA or RNA virus?
Enveloped or nonenveloped virus?
Double or single strand?
Hepadma is an enveloped DNA virus.
Double stranded.
Polyoma
DNA or RNA virus?
Enveloped or nonenveloped virus?
Single or double stranded?
Polyoma is a non enveloped DNA virus.
Double stranded.
Papilloma
DNA or RNA Virus?
Enveloped or nonenveloped virus?
Papilloma is a non enveloped DNA virus.
Double stranded.
Adeno
DNA or RNA Virus?
Enveloped or nonenveloped virus?
Adeno is a non enveloped DNA virus.
Double stranded.
Parvo
DNA or RNA Virus?
Enveloped or nonenveloped virus?
Single or double stranded?
Parvo is a nonenveloped DNA virus.
Single stranded. (SS)
Negative RNA is enveloped or noneveloped?
Negative RNA is always enveloped.
Can all viruses enter all cells?
No, viruses are specific for certain types of cells.
Types of viral entry into the cell
- Fusion (enveloped)
2. Endocytosis
What types of viruses use endocytosis to enter the cell?
Enveloped and nonenveloped viruses can enter a call via endocytosis, although it changes slightly.
Process for fusion cell entry (enveloped)
- Virus spikes bind to the receptors on the surface of host cells
- Lipid bilayer of viral envelope fuses with the host cell membrane
- Nucleocapsid is released into the cytoplasm
Process for endocytosis (enveloped)
- Viral envelope spikes bind to the receptors, tricking it to think it’s an important carbon)
- Binding to the receptor triggers receptor mediated endocytosis
- Increased acidity allows nucleocapsid to escape from the endosome and enter the cytoplasm.
Process of bacteriophage “life cycle” via lytic pathway
- virus injects DNA or RNA into the cell (spider looking virus)
- replicates virus genomes
- busts out of the cell via lysis
- Viruses have then replicated and go to infect other host cells to do the same process
Process of bacteriophage “life cycle” via lysogenic pathway
- virus injects DNA or RNA into the cell (spider looking virus)
- hijacks cells DNA and replication process
- Completes cell division and host cell keeps living
(Ticking time bomb as if anything attacks the cell, the virus resorts back to the lytic pathway where cell explodes and newly replicated viruses attack other cells)
What are the two types of life cycles for the bacteriophage?
- Lytic Pathway
2. Lysogenic Pathway
Who discovered the first virus and when?
Walter Reed in 1901
What are two examples viruses are used for good?
- strengthen disease resistance crops
2. HIV helping with cancer treatments
What’s the theory many scientists agree with?
Millions of years ago, viruses helped form the first cell nucleus when trying to infect a bacterium.
Viruses consist of what?
RNA or DNA and a protein coat
How do virus’ reproduce?
Inserting DNA into a host cell
Retroviruses are different from regular viruses because they:
Have RNA instead of DNA
Vaccines can be used to prevent viral infection by what?
Creating an immune response in the host
Why do some viruses seem to go away and come back, like a cold sore?
The virus has entered the lysogenic cycle
Why is it more difficult to create a vaccine for retroviruses?
RNA mutates more frequently than DNA
What happens after the virus has been taken up by the cell?
It inserts into the host DNA
True or False: Some viruses have single stranded RNA genomes
True
True or False: Viruses are living
False
An individual virus is called a particle or a what?
Virion
Which of the following is not a form of viral entry?
- Fusion of enveloped virus
- Fusion of naked virus
- Endocytosis of naked virus
- Endocytosis of enveloped virus
Fusion of naked virus
Poliovirus and coronavirus have a _____ genome.
+ RNA
What body site is typically the first to be colonized by microbes after birth?
Skin
True or False: Bacteria do not normally inhabit the epidermis.
True
True or False: Reverse Transcriptase can degrade DNA.
False
The colon lacks oxygen, therefore it is an ______ environment.
Apoxic
Mechanisms of tissue specificity in microbes include tissue tropism, specific adherence, and _________.
Biofilm formation
Name a body site that is normally sterile.
Heart
What enzyme is required by viruses to make RNA from RNA?
RNA Replicase
What type of template is needed to make a -RNA genome?
+ RNA
This is a -RNA virus with a naked capsule. What is the virus type and what’s an example?
Picornaviruses.
poliovirus, Hepatitis A, Rhinovirus
This is a -RNA virus that is enveloped. What is the virus type and what’s an example?
Coronaviruses.
SARS
In poliovirus replication, RNA replicase can create _____ and ______ RNA.
+ and -
This is a - strand RNA virus in animals that is enveloped. What is it and what’s an example?
- Rhabdoviruses (Rabies Virus)
- Orthomyxoviruses (Influenza)
- Ebola Virus
How does influenza bring viral proteins into host cell?
RNA replicase, RNA endonuclease, steals RNA cap from host RNA and tricks it into producing its RNA.
What virus types are referred to as the common cold?
Adenoviruses.
Upon cell entry, this virus type is in the lysosome.
Reoviruses
Retrovirsues bring what with them?
They bring their own mRNA
Retroviruses
- enveloped virus with 2 copies of RNA genome and specific enzymes for reverse transcriptase
- bring their own mRNA
- retroviruses are proviruses and can remain latent in host chromosome until they get the right signal
Reverse Transcriptase phases
- Reverse transcription ( DNA - RNA)
- Synthesis of DNA from DNA template
- RNase H activity - degrades RNA of DNA hybrid
normal microbial flora is found where?
nose, throat, eyes, mouth, skin, large intestine, urinary and genital systems (urethra and vagine)
What determines normal flora?
ph, temperature, oxygen, water, and nutrient levels are main factors determining composition of the normal flora
When does colonization of microbes start?
At birth and the skin is normally the first site to be colonized.
mixture of organisms regularly found on surface tissues
normal microbial flora
Where are most microbes on the skin located?
apocrine sweat glands and hair follicles
What are common microbes found on the skin?
- Streptococcus
- Staphylococcus
- Corynebacterium
- Propionibacterium
What type of gram stained bacteria thrive in a dry environment like skin?
Gram positive bacteria
What type of normal flora is located in the conjuctiva (white part of eyes)?
- Staphylococcus epidermidis
2. Propionibacterium acnes
What type of microbe usually results in dental plaque?
streptococci
normal flora of gastrointestinal tract
helicobacter pylon (gram negative) and can make ulcers
normal flora of respiratory tract
staphylococcus epidermiditis
cornybacteria
True or fasle: the sinuses and lower respiratory tract should be sterile.
true
normal flora of urethra
staph. epidermidis
entococcus faecalis
beneficial effects of normal flora according to mouse study
increase in vitamins prevent pathogen colonization increase immune system increased natural antibodies stimulated development of certain tissues
What are the harmful effects of normal flora?
- bacterial synergism (cross feeding between microbes)
- competition for nutrients (could deplete host of nutrients)
- agents of disease (opportunistic pathogens)
Babies born via c-section are more likely to have what?
leukemia, asthma, and immune diseases
How long does it take for a newborn to develop normal microbial flora?
2 years
Types of bacterial pathogens
- potential pathogens
- opportunistic pathogens
- obligate pathogens - will make you sick if exposed
mechanisms of bacterial pathogens
- exposure to pathogens
- adherence to skin or mucosa
- invasion through epithelium
- colonization and growth of virulence factors
3 types of toxins
- exotoxins
- enterotoxins
- endotoxins
toxin proteins released from the pathogen cell as it grows
exotoxins
toxin that effects the small intestines and tells cells to release fluid into intestinal lumen, resulting in vomiting and diarrhea
enterotoxins
toxin that tells the lipopolysacchoride (LPS) portion of the cell wall of gram negative bacteria is a toxin
(cell bound)
endotoxins
True or false: exotoxins do not trigger fever or strong immune system response
True
toxicity and ___________ can happen at the same time but do not have to
invasiveness
study of the occurrence, distribution, and determinants of health and disease in a population (public health)
epidemiology
disease occurs in a high number of the population at the same time
epidemic
disease is widespread and usually worldwide
pandemic
when disease is constantly present but at a low incidence (plague in southwest USA)
endemic
the number of new cases of a disease in a population over a given time period (ex. Kentucky had 1,400 new coronaviruses cases since 4 pm yesterday)
incidence
total new and existing cases in a population during a given time (example: Kentucky had had a total of 94,000 coronavirus cases since March, 2020)
prevalence
number of cases observed in an area with previously sporadic cases
outbreak
person with a subclinical infection that can spread a disease
carrier
incidence of death in the population
mortality
incidence of disease in a population
morbidity
organism invades and grows in a host
infection
the time between exposure to the disease and appearance of symptoms
incubation period
when the disease is at its height with symptoms
acute period
when symptoms start to subside
decline period
when a patient regains strength and returns to normal after having a disease
convalescent period
some organisms become __________ and stay with you forever.
latent
Typhoid Mary was a ___________ for the typhoid fever.
Reservoir
when an infected person transmits a disease directly to an uninfected host without an intermediate (cold flu, STDs)
host to host
transmission from person to person via an intermediate
indirect host to host
living agents of transmission
vectors
non-living intermediates (surfaces, bedding, toys, etc….)
fomites
true or false: pathogens that live in soil or non-host environment do not typically evolve to be less virulent
True because they do not need a host to survive (cannot be virus, only bacteria)
True or false: some pathogens evolve into stronger infectious agents.
True
You cannot travel internationally and must be treated and quratine in place if you have any of the following diseases.
smallpox, cholera, plague, yellow fever, typhoid fever, relapsing fever
What does the public health do?
- control the reservoir (immunize or destroy animals)
(immunize or quarantine infected humans) - control transmission
- immunization (provideas herd immunity)
- quarantine (until communicable stage is passed)
