Microbiology Exam 2

Are Viruses Living or Nonliving?

They are only considered living when they are inside of a host cell, using their resources and energy.

Outside of a host they are considered intert.

When are Viruses considered to be "alive"?

When they are inside of a host cell.

When inside, their nucleic acid (ONLY RNA OR DNA) become active.

*Virus replicates

Obligatory Intracellular Parasites

Require livinghost cell in order to multiply - Such as Viruses.

Defining a Virus

1) Contains 1 Nucleic Acid (DNA or RNA)

2) Protein coat surrounds the DNA or RNA

3)Multiply within host using host machinery

---because they don't have the ways of making/obtaining their own nutrients. like ATP or enzymes.

Virus Characteristics

*Some are enclosed by an envelope which consists of lipids, proteins, carbohydrates

*some have spikes

*only infect the cells of ONE host.

Host Range

The spectrum of host cells that a virus can infect.

-invertebrates

-vertebrates

-plants

-protist

-fungi

-bacteria

The virus must be able to attach to a the particular host's cell.

**Host range is determined b specific attachment sites on the host cell's surface

Bacteriophages

Bacteria that is infected by a virus

How do Viruses attach to a host cell

Through receptors on the host cell's surface.

There must be an interaction.

Capsid

Protein coat that surrounds the Nucleic Acid of a virus. (not the whole virus itself. That's an envelope.)

***Made up of individualized Capsomeres***

*accounts for most of the mass of a viral cell.

Capsomeres

Protein subunits that make up a capsid

(think of tiny balls that come together to make a huge coating around the Nucleic Acid)

*capsomeres can be made up of multiple types of proteins or one single type of protein

Envelope

Surrounds the virus as a whole.

*Synonymus to a somatic cell's Plasma Membrane. But around a virus.

***Composed of proteins, lipids and carbs.

*Could be covered in spikes

NOT ALL VIRUSES HAVE ENVELOPES

Spikes

Cover the envelope of the cell

Composed of protein and carbohydrates.

-Used for attachment to the host cell

Spikes differ, and can be identified as different virus by the host body. That's why you can get the flu more than once a year, there's a change in spikes.

-Can be used for identification for some virsus under microscope.

Helical Capsid

Long rods that are flexible and rigid

These surround the Nucleic Acid.

*Capsids are hollow cylinders surrounding the nucleic acid.

*CAN OR CANNOT HAVE A ENVELOPE.

Without envelope = they look like long noodles, because it's just the capsid and no sphereical shape

WITH the envelope = they look like balls, but with their Nucleic acids all tangled inside.

Polyhedrical Capsid

These are icosahedron, and are 20 triangle shapes, with 12 corners.

THEY CAN BE WITH OR WITHOUT ENVELOPE

-Without envelope, you can see their individual caposomere and their many different triangular faces of the Capsid

WITH envelope, they appear ordinarily spherical, and like a normal cell. (Some have spikes)

Complex Capsid

They have a variety of weird shapes within the one virus cell, and look just straight up weird.

They can be bacteriaphages and just look mutuant

Family names suffix for Taxonomy

-viridae

Ex. Herpesviridae

Genus name suffix Taxonomy

-virus

Genus Simplexvirus

Ex. Herpesvirus

Viral species

A group of viruses sharing the same genetic information and ecological niche (niche=host)

Viral species are designated by descriptive common names, such as human immunodeficiency virus (HIV),

Subspecies

They are determined by the NUMBER that is attached to the specific genus of the family. These are viruses that can affect humans

HIV-1, HIV-2

Plaque

Areas of clearing where the the virus has killed the bacteria

PFU

Plaque Forming Unit

*Concentrations of viral suspensions measured by the number of plaques

Cytopathic Effect

CPE

This is cell deterioration after a virus infects a monolayer of cells that appears to be growing just fine.

The cells clump together as they deteriorate.

Virion

Complete, fully developed, infectious viral particle composed of nucleic acid and surrounded by protein coat that protects it from the environment and is a vehicle of transmission from one host cell to another.

**AKA MATURE PHAGE

Lytic Cycle

The cycle that bacteriophages use to multiply.

WHERE THE CYCLE ENDS WITH LYIS AND DEATH OF HOST CELL.

Lysogenic Cycle

The cycle that bacteriophages use to multiply.

Where the host cell remails alive after the cycle.

Phage Lysozyme

Enzyme released by the bacteriophage tails to break down bacteria cell wall so they can enter the bacteria.

Lytic Cycle of a T-Even Bacteriophage

1) ATTACHMENT to bacteria cell wall by tail fibers to complementary receptor sites

2) ENTRY of viron DNA inside the bacteria, and the protein capsid is left outside of the bacteria cell

3) BIOSYNTHESIS goes underway to use the host machinery to interfear with host DNA synthesis, and makes the phage DNA instead

4) MATURATION is undergone when capsids are assembled around the DNA, and the "assembly line" happens to form the virions

5) RELEASE or LYSE happens when the new virions are released to infect other cells. The host cell does not survive through this cycle.

Prophage

The Virus and the bacteria's DNA combined into one.

Oncogene

a gene that can bring about malignant transformation

*Also called a cancer causing gene

Pathology

Scientific study of disease

"Patho" disease/suffering - Logos "study of/science"

=Concerned with the changes brought by the disease and change it has on the body.

Pathogenesis

The MANNER in which a disease DEVELOPS

Eitology

The study of the CAUSE of the disease

Koch's Postulates

1) Same pathogen must be present in EVERY CASE of the disease (aka to be consistant)

2) Pathogen must be isolated from the disease host and grown in pure culture

3)Pathogens from the pure culture must cause the disease when it is incoulated into a healthy, suspetible lab animal and then cause disease

4) The pathogen must be isolated from the inoculated animal and must be shown to be the original organism

- Both organisms infecting both host must match the kind of organism that is grown and extracted.

Koch's Postulates

Used to determine the causative agent for bacterial diseases

Symptom

SUBJECTIVE

A change in a body function that is felt by a patient as a result of disease.

-Subjective and not measurable by empircial data: PAIN.

Sign

OBJECTIVE

A change in a body that can be measured and obsterved

-Anything empirical: Lesions, fever, swelling

Syndrome

A specific group of signs and symptoms that accompany a specific disease

Communicable Disease

Any disease that spreads from one host to another, directly or indirectly.

Contagious disease

A communicable Disease that is EASILY spread from one person to the next.

Non-communicable disease

Not spread from one host to another

*the microbes exist outside the body, and only produces disease when introduced inside

TETANUS

Incidence of a disease

Number of people who DEVELOP and contract this disease within a certain period of time.

*Diagnosed cases of HIV in 2009 alone

Prevalence of a disease

Number of people EXISTING WITH the particular disease at a given time.

*Known cases of HIV at the point of year 2009

TAKES INTO ACCOUNT OLD AND NEW CASES FROM YEARS BEFORE

Sporadic Disease

Occurs only OCCASIONALLY

*Typhoid fever within the US

Endemic disease

A disease that is constantly present in a population

*Common cold

Epidemic Disease

If many people in a CERTAIN AREA acquire a certain disease in a relatively SHORT PERIOD of time.

*Influenza, AIDS

Pandemic Disease

An epidemic disease that occurs worldwide

*A worldwide Influenza, and AIDS

Acute Disease

A disease that develops rapidly but only last for a short period of time

*influenza

Chronic Disease

Develops slowly, and the body's reactions might be less severe, but the disease is likely to continue to recur for long periods of time.

Subacute Disease

Symptoms between acute and chronic diseases - in the middle

*Infection and bronchitis.

Latent Disease

Causative agents are inactive for long periods of time, then becomes active to produce symptoms

*any latent viruses of the Herpesvirus family. Such as shingles or chicken pox that lay on the nerve cells.

Herd Immunity

When many immune people are present in a community

When the number of people vaccinated goes UP,

The chance of the risk to encounter the disease goes DOWN.

Local infection

Invading pathogens are limited to a small area of the body.

*Boils and absecesses

Systematic (generalized) infection

Spread THROUGHOUT the body bu blood or lymph

*measles

Focal Infection

Systematic infection that BEGAN as a local infection

*Local infections can enter blood or lymphatic vessels and can spread to other specific parts of the body

*can arise in areas such as teeth, tonsils, or sinuses

Sepsis

Toxic inflammatory condition arising from the spread of microbes from a focus of infection

Septicemia

Blood poisoning

*multiplication of pathogens within the blood

Bacteremia

Bacteria in the blood

Toxemia

Presence of toxins within the blood

Viremia

Presence of virus in the blood

Primary Infection

Acute infection that causes an initial illness

Secondary Infection

Caused by opportunistic pathogen after immune system weakened by primary infection.

Pneumonia is a consequence of AIDS, and is a secondary infection.

Predisposing Factors

Makes the body more suspectible to diease and may alter the course of disease.

*gender (females have higher incidence of UTIs

*genetic background ( inherited genes from parents like sickle cell anemia)

*Lifestyle/Occupation

*Climate/Weather

Stress/Fatigue

Subclinical Disease

An infection that doesn't cause any noticiable illness

Poliovirus and hepatitis A. You can carry it but you never contract it.

Reservoirs of infection

Can be human, animal, or nonliving

carriers

Those who carry the pathogens and transmit them to others without exhibiting any sign of illness

Zoonoses

Diseases that occur in wild and domestic animals and can be transmitted to humans

*rabies

*Lyme disease

Noliving Reservoirs of Infection

Soil

AND

Water.

Bacteria strands can be found within them and contaminate them and then they can infect humans

3 means of disease transmission

1) Contact (by means of direct contact, indirect contact, or droplet transmission)

2) Vehicle (Transmission via a medium like food, water air, blood, bodily fluids, air)

3) Vectors (animals that carry pathogens to host)

3 types of CONTACT transmission

1) Direct Contact - Kissing touching hugging

2) Indirect Contact-Fomite(something normal infected)

3) Droplet transmission - microbes spread by coughing, sneezing, laughing, talking

Pathogenicity

The ability to cause disease by overcoming the dfense of the host

Mechanical transmission

Passive transport

(fly landing on burger)

Virulence

The extent oe degree of pathogenicity

AKA DANGER

Biological Transport

Active process.

Mosquito biting an individual, giving malaria.

Portals of Entry

1) Mucous Membranes

2) Skin

3) Direct deposition beneith the skin or membranes

- (the parenteral route)

Epidemiology

The study of when/where disease occurs and how disease is transmitted in populations

**there is always an epidemiologist at each large hospital to prevent nosocomial diseases and keep them under control.

Portal of Entry - Mucos Membrane

Lining of GI

Respiratory tract

Genitoruitary tract,

Conjunctiva (eyeball and the lining of it)

Most common way is GI and Respiratory tract.

Case Reporting

Health care workers must report specified disease to local, state, and national offices

-by doing this, (by law) this documentation raises awareness so the nation can prevent epidemics or a pandemic from occuring.

*examples: AIDS, measles, gonorrhea tetanus, typhoid fever.

CAN LEAD TO EDUCATION ABOUT ILLNESSES.

ID(subscript)50

ID= Infectious Dose

Infectious dose for 50% of population

***How many endospores that are necessary to infect 50% of the population.

Nationally Notifiable Diseases

Diseases in which physicians are required by law to report.

LD(subscript)50

LD=Lethal Dose

Lethal Dose (OF A TOXIN) for 50% of population.

Morbidity Rate

How many people are affected by disease

Adhesin

Also called a ligand that helps the pathogen adhere to the host cell in order to invade it

*Located on the pathogen.

Mortality Rate

How many people have died resulting from this disease

M Protein

Surface Protein in Cell wall component of bacteria that helps with bacterial attachment to an epithelia cell

Resists phagocytosis of WBC

***INcreases Virulence of the bacteria

Microbial antagonism

Competition for nutrients

****When normal microbiota can prevent pathogens from causing an infection

Mycolic Acid (Waxy Lipid)

A cell wall component that can prevent phagocytosis

It can even multiply within the phagocyte

Coagulases

Form blog clots within the blood.

An enzyme that a pathogen uses to clot the blood to prevent phagocytosis

What causes Staph to be so deadly and prevent blood from flowing to parts of the body

Collagenase

Enzyme produced by bacteria.

It breaks down the protein collagen and breaks down the connectrive tissue of muscles and other body organs and tissue.

IgA Proteases

Enzymes that the bacterial cell can give off to Destroy antibodies

Antigenic Variation

Antigens line the ouside of a bacterial cell for the attachment to the host cell.

The body makes antibodies to attach to these antigens to destroy them and prevent their wrongdoing

However, when pathogens alter their surface antigens, making the antibody that the body made unusable.

THIS SNEAKY SNAKE MOVE IS ANTIGENIC VARIATION.

By the time the immune response reaches a pathogen, the pathogen has already alters its antigens and is unaffected by antibodies.

***The flu does this

Siderophores

The iron sealing protein that bacteria use to attach to the iron tigher than the iron within the host cell's

Toxic

Substance that contributes to pathogenicity - creates disease

*Poisonous substatnces that are produced by certain microorganisms

---They are transported through the body by blood, or lympth.

CAUSE

*Fever

*Cardiovascular disturbances

*diarrhea

*Shock

Toxigenicity

Ability to produce a toxin

Toxemia

Presence of toxic in the host's blood

Antitoxins

Antibodies made within the host cell (humans) that can resist the presence of exotoxin (the proteins that are expelled from the gram positive cell)

Toxoid

A type of inactive toxin (that is changed by heat, or other chemicals) that a person can take that will up their production of antitoxins within the body)

*Ex. are the Diptherioa and tetanus shots that can be used to avoid toxicity in the body.

Exotoxins

Causes damage to cell host

A type of protein made inside of the pathogen.

These exotoxins are then secreted into the surrounding metium, and then the cell dies.

=Toxins made within the cell and EXO the cell, leading to its death

First way that bacteria cells make toxins for the spreading of disease.

GRAM POSITIVE

Endotoxin

Causes damage to host cell

The LIPID portions of the outer membrane of cell wall.

The exotoxins are liberated when the bacteria cell die and the cell walls break apart

This is the second way that toxins are produced from bacteria cells

GRAM NEGATIVE

Membrane Disrupting toxins

A type of toxin released from the pathogen that causes lysis of the cell by:

1) forcing the formation of protein channels in the plasma membrane,

2)DIsrupting the phospholipid bilayer of the host cell.

Superantigens

Causes an intense immune response due to release of cytokines from host cell.

Such as:

-Fever

-Nausea

-Vomiting

-Shock

-Diarrhea

-Shock

-Death

An intense response could be that of Toxic shock syndrome or food poisoning.