microbio ch 14 study guide: biomed applications

what was the chinese procedure called variolation? what pathogen were the practitioners trying to gain protection from?

powder made from dried scabs of smallpox, practitioner blew the powder into healthy individual's nose; smallpox

what was edward jenner's contribution to science? what pathogen was involved?

- purposely inoculated a boy a cowpox pus
- boy contracted cowpox, but quickly recovered
- jenner then infected him with smallpox, but he showed no symptoms

what was louis pasteur's contribution to vaccine development?

- early version of the rabies vaccination to protect humans
- vaccination to protect cattle against anthrax

in the 20th century, smallpox was eradicated. what is the next disease targeted for eradication? why might this be difficult to achieve?

polio; maintaining consistent vaccination access

describe the 1998 study that was published in The Lancet that harmed vaccination efforts. what was the vaccination in question and what happened to the study and lead author?

- study of 12 patients; claimed a correlation between the measles, mumps, and rubella vaccination and development of autism
- shortly after publication, many parents in the US and UK started to decline MMR and many other vaccinations for children

what disease is showing the strongest reemergence in the US and UK due to declining vaccination rates?

measles

vaccines induce which type of immunity?

artificially acquired active immunity

what must be stimulated for a vaccine to be considered effective?

immunological memory without causing the disease they aim to prevent

what is herd immunity?

when a disease has difficulty spreading through a group of people

what two vulnerable populations are protected by herd immunity?

premature babies and immune-compromised patients

explain what the statement "shingles is a sequela to chickenpox" means

shingles is a consequential condition of chickenpox

what are live attenuated vaccines?

contain altered pathogens that do not cause disease, but are still infectious

what is the benefit of live attenuated vaccines? what are three drawbacks of live attenuated vaccines?

- benefit: stimulated potent immunological responses that are accompanied by long-lived memory
- drawbacks: could cause disease in an immune-compromised host, possible mutation to an infectious form, and often must be refrigerated

what are inactivated vaccines?

consists of whole inactivated pathogens, includes whole-agents and subunit vaccines

what are two advantages that inactivated vaccines have over live attenuated vaccines? what is one disadvantage?

- advantage: safe for immune-compromised patients and stable at room temperature
- disadvantage: boosters required to achieve full immunity

what is the difference between inactivated whole-agent and inactivate subunit vaccines? what is one advantage that whole-agent vaccines have over subunit vaccines?

- whole-agent: contain the entire pathogen, inactivated by heat, chemicals, or radiation
- subunit vaccine: do not include whole pathogens, consist of purified antigens or parts of the infectious agent, require adjuvants, and include purified subunit vaccines, toxoid vaccines, and conjugate vaccines

what is an adjuvant? what type of vaccines use adjuvants?

- adjuvant: pharmacological additives that enhance the body's natural immune response to an antigen
- subunit vaccines

what is a recombinant subunit vaccine?

harvested from a natural pathogen or purified from a genetically engineered expression system

what is a toxoid vaccine? give two examples of vaccines that have toxoid components.

- purified and inactivated toxins
- tetanus and diphtheria of DTaP and Tdap

what are conjugate vaccines? what are two molecules are usually conjugated? why must this be done?

- polysaccharide antigens conjugated to a more immunogenic protein antigen
- conjugation stimulates a sufficient immune response

what are mRNA vaccines?

- purified mRNA is encased in lipids chemically compatible with the cell plasma membrane
- mRNA is delivered to host cells which translate the mRNA to build an antigenic protein that triggers an immune response

what are recombinant vector vaccines?

select genes from a pathogen are packed inside a harmless virus or bacterium, inserted into the body

what are DNA vaccines? what two diseases/infections are the focus of DNA vaccine development?

- genes encoding highly immunogenic antigens are identified
- target genes are placed into a plasmid; plasmid is injected into a human host; human cells take up the plasmid and transcribe and translate the genes; cells become antigen producers
- focuses on HIV or cancer

define serology

study of what is in a patient's serum

what is agglutination? what two molecules are required for positive agglutination reactions?

- antibodies can bind antigens into a clump
- antibodies and antigens

what type of serological test is used for blood typing and confirming a syphilis diagnosis?

- agglutination
- treponema pallidum particle agglutination assay

describe the steps of plaque neutralization tests (PRNT). what is the test detecting?

- patient's serum is extracted and serially diluted; preparation of the suspected virus is added to the various tubes of diluted serum; each serum/virus mixture is added to petri plates of cultured cells and incubated
- positive: neutralizing antibodies present in the patient sample; antibodies bind to the added virus and neutralize them
- negative: no neutralizing antibodies present in the patient sample; patient sample and control culture exhibit same level of infection

what is plaque?

areas that develop in a lawn of cultured cells as the cells are infected and lysed by a virus

what does a direct ELISA detect in a patient's serum? what does a positive reaction indicate?

- identification of antigens or antibodies in a sample
- if the antigen of interest is in the wells, then the detection antibodies will directly bind it

what does an indirect ELISA detect in a patient's serum? what molecule is coated onto the wells of the microtiter plate? what does a positive reaction look like? what does a positive reaction indicate?

- determining if a patient has antibodies to a particular pathogen
- known antigens
- any patient antibodies that recognize the antigens coating the wells will bind

what does a sandwich ELISA detect in a patient's serum? what molecule is coated onto the wells of the microtiter plate? what does a positive reaction look like? what does a positive reaction indicate?

- detect a specific antigen in a sample
- capture antibody
- antigens in the sample that bind the capture antibody will do so; a second antigen-specific antibody is added and allowed to bind

what is an immunofluorescence microscopy? what molecule is fluorescent tagged? what is the tagged molecule detecting?

- utilizes fluorescent-tagged antibodies to recognize a specific antigen in a sample
- antibodies: recognize a specific antigen

what is flow cytometry? what special piece of equipment is required for flow cytometry?

- allows for enumeration of specific cells
- requires fluorescence-activated cell sorter

what are IGRAs? what is this assay mainly used for in the US? what is this assay detecting?

- fast and reliable way to detect TB in the early stages in vaccinated populations
- measure patient's T cells response to Mycobacterium tuberculosis antigens

what molecules do western blots detect? how is a western blot performed?

- protocol that detects specific proteins in a sample
- reveal what proteins are present as well as their levels, provide added information about the size of the protein being detected
- starts with separating proteins by size using a technique called electrophoresis

what does the abbreviation PCR stand for? what does this application detect?

polymerase chain reaction; detect a single pathogen

where is Taq polymerase derived from? why is it used in PCR?

an enzyme from the hot springs' bacterium Thermus aquaticus

what is a thermocycler? when performing PCR, three different temperatures are cycled. what occurs during each temperature range?

- machine used to perform polymerase chain reaction
- melting step: high temperature (95-99 C) to separate double-stranded DNA
- annealing step: lower temperature (50-65 C) allows the primers to anneal with the template DNA
- extension step: optimal temperature (65-75 C) for DNA polymerase to copy target DNA

what is gel electrophoresis used for?

analyze amplified DNA

what is real-time PCR (also called quantitative PCR or qPCR)?

modified PCR that used fluorescence imaging to visualize DNA copies as they are made, allow technicians to see data immediately

what is RT-PCR? what does it detect?

useful for detecting RNA in a sample; reverse transcription PCR

in addition to Taq polymerase, what is another enzyme used when performing RT-PCR? what is the function of this enzyme?

- reverse transcriptase: builds DNA that is complementary to target RNA molecules in a sample

why was the genetic information nondiscrimination act of 2008 passed?

attempt to protect patients from discrimination based on genetic information

what does the term recombinant DNA refer to?

- provide a way to insert a desired gene into an expression system
- allows proteins to be produced in large amounts
- DNA is generated or engineered by combining DNA from different organisms

what are restriction enzymes?

enzymes that are used to generate compatible or sticky ends of complementary base pairs between the copied DNA and the plasmid to construct recombinant DNA

what is transformation?

a process by which cells take up DNA from their environment

what type of tool is CRISPR-Cas9?

gene-editing tool

what does the Cas9 part do?

scalpel that cuts the DNA sequence once it is located

what is gene therapy?

process of introducing genetic material that is not a human cell as a treatment

in general, what do microarray assays investigate?

the expression levels of thousands of genes simultaneously