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vaccines and HIV (strand 2) - Coggle Diagram
vaccines and HIV (strand 2)
passive immunity
process
antibodies enter from an outside source
no direct contact with pathogen or antigen
immunity is acquired immediately
once antibodies are broken down immunity is lost
no memory cells
active immunity
process
antibodies stimulated by own immune system's contact with pathogen or antigen, takes time to develop, generally long lasting
two types
natural ~ individual infected normally with pathogen
artificial ~ vaccination, inducing an immune response in an individual without them suffering the symptoms
herd immunity - so many people are vaccinated that the pathogen is unlikely to come into contact with someone who isn’t vaccinated so it doesn’t spread
HIV
structure
HIV is a complex enveloped retro virus
has 2 copies of mRNA
protein capsid
lipid envelope formed from host cell membrane as they emerge from cell cytoplasm
viral attachment proteins
T helper cell infection
process
HIV invades T helper cells
attachment protein on virus surface binds to CD4 receptors
virus fuses with T helper cell
viral RNA and reverse transcriptase enter the cell
once inside T helper cell, virus needs to make host cell replicate new viral components, HIV nuclear material is RNA not DNA
therefore transcription is reversed and DNA is made from RNA
viral enzyme, reverse transcriptase is used to do this, HIV is a retrovirus and contains RNA and uses reverse transcriptase
viral dna integration
process
once HIV DNA strand is produced, it is integrated into host's DNA
once HIV genome is integrated into host cell's genome, it is transcribed and translated into new proteins
the new viral particles are then released taking some of the cell surface membrane with it