microbiology in diagnostics Flashcards
define BCA
a biological control agent. this is microorganisms which are used to protect plants against pests and pathogens
what is direct BCA action
BCAs suppress pathogens by producing anti microbial compounds to degrade it
what is indirect BCA action
BCAs colonise the plant to prevent unwanted colonisation via niche exclusion
what is host mediated BCA action
BCAs induce the plants own defence mechanisms
what is SAR
systemic acquired resistance. this is whole plant resistance generated by earlier exposure to a localised infection
what is ISR
induced systemic resistance. this is resistance elicited by BCA colonisation- specifically non pathogenic rhizobacteria which promote plant growth
how does viral pathogen- derived resistance work
it uses cross protection whereby inoculation with a mild strain can offer protection against similar strains- they have to be very similar though so it’s not economically viable
how does bacterial pathogen- derived resistance work (it is the same in fungi)
introduction of pathogenic genes gives the plant resistance to the toxins produced by the pathogen
describe the steps to immunological diagnostic techniques
genes are cloned and proteins produced in vectors, or the proteins are purified directly from pathogens. they are then injected into animals which produce antibodies which can be recovered by bleeding
describe the steps to the ELIZA assay
a place is coated with a sample. antibody- enzyme conjugates are added. the plate is washed and then substrates added. if a reaction occurs then the enzymes must be present, meaning the antibodies bound and therefore the pathogen is present
describe how lateral flow works
there are two capture zones. one with antibodies for normal antigens of the animal the sample was grown in and the other specific to the pathogen. two lines indicates a positive test
how does PCR identify pathogens
due to primers being designed specific to the pathogenic DNA. real time PCR is at lower risk of contamination than basic due to the tubes being closed
how is LAMP different to PCR
they are similar methods but LAMP amplifies the DNA at one temperature (65C)
what is the advantage of array technology
it can test for up to 48 pathogens from one sample due to different primers being designed and imprinted into different tubes
how does biosensing work
it detects the chemicals released by certain pathogens using an ‘electric nose’
