3.2.4 (2) HIV and Elisa Tests

Human immunodeficiency virus (HIV)

a retrovirus which targets the immune system

Retrovirus

containing reverse transcriptase which is able to synthesise single-stranded DNA (cDNA) from an RNA template

HIV’s effect on the immune system

Infects and destroys the Helper T cells

Causes AIDS leaving them susceptible to infections such as pneumonia

Structure of a HIV particle

Capsid-containing RNA and reverse transcriptase

attachment protein

lipid membrane

HIV replication in T helper cells

-Attachment proteins attach to receptors on helper T cell/lymphocyte;

-RNA and reverse transcriptase enters cell

-Reverse transcriptase converts RNA to DNA

-Viral protein/capsid/enzymes produced

-Virus (particles) assembled and released (from cell)

antiretroviral drugs

drugs designed to reduce production of HIV by targeting different stages of its life cycle

what may be in antiretroviral drugs

proteases

reverse transcriptase inhibitors

ELISA test

uses antibodies to quantify the level of a protein

amount of washes in an ELISA test

3 times

Enzyme Linked Immunosorbent Assay

ELISA Test

ELISA test method

-plastic plate with wells

-antigen added and sticks to material at bottom of well

-wells are washed to remove antigen molecules which didn’t stick

-specific antibody to antigen added

-wash again to remove excess antibody

-second antibody with enzyme added

-wash again

-substrate added which enzymes converts to coloured product

-after fixed time waited intensity of colour produced indicates number of antigens present

uses of monoclonal antibodies

ELISA test, Lateral flow test (pregnancy)

why you use a number of different dilutions when doing an ELISA test

to ensure all the antigens stick to the plate and the well is not too overloaded with antigen

Virus ELISA tests are effective at testing for

HIV