Genes&Society_2 BW slide perpage_Lecture12

W french anderson then at the nih treated a

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Unformatted text preview: r 1990 human being was made in September, 1990. W. French Anderson, then at the NIH, treated a fourfouryear-old Cleveland girl named Ashanti DeSilva suffering from a kind of severe combined immune deficiency (SCID) This is caused by mutation in the gene for an This is caused by a mutation in the gene for an enzyme enzyme called adenosine deaminase, or ADA It cripples the immune system leaving its victims It cripples the immune system, leaving its victims defenseless defenseless against infections. Before 1990, the only effective treatment was a bone 1990 th 13 marrow transplant Gene Therapy for ADA-SCID ADA•Remove white blood cells (WBC) •Infect WBC with retrovirus with ADA gene in culture Infect WBC with retrovirus with ADA gene in culture dishes dishes in the lab •ADA gene integrated and expressing proteins ADA •Blood cells infused back into the body •Health restored BUT - needs repetitive transfusions for new WBC as these get destroyed by the body every few 14 weeks To treat SCID using gene therapy, cloned To treat SCID using gene therapy, a cloned human ADA gene is transferred into a viral vector, which is then used to infect white blood cells removed from the patient. The transferred ADA gene is incorporated into a chromosome and becomes active After chromosome and becomes active. After growth to enhance their numbers, the cells are reimplanted into the patient, where they produce ADA, allowing the development of an immune response. 15 Cystic Fibrosis (CF) 1 in 2000 (Caucasian) newborn are sufferers, 1 in 2000 (C 24 adults are heterozygous carriers Autosomal (i.e. not sex-linked), recessive trait sexIt is the result of ove -production of sticky mucous – er st which causes problems particularly in the lungs (breathing) and pancreas (thickened pancreatic secretions secretions unable to be released into duodenum – caused damage to pancreas). Prone to lung infections and breathing problems, poor digestion and diabetic In 1989 the gene responsible for CF was isolated 16 17 rep gene cftr gene Remove the rep gene which encodes replication replication proteins cap gene 18 Cystic Fibrosis (CF): routes to somatic gene therapy • Functional CF gene isolated and cloned into bacteria to produce many copies. • CF gene is transfer into viral vector and package into modified virus (problem to package into modified virus (problem to find find the right one!) • Modified virus will introduce vector into Modified virus will introduce vector into cell cell and vector helps to integrate CF gene integrate into chromosome of host lung cells. into chromosome of host lung cells. •functional proteins are expressed. 19 Cystic Fibrosis (CF): the vector problems… •Liposomes: not integrated into host DNA •Retrovirus: cancer causing?? ca caus •Cold virus: inflammation of lungs •Repetitive infections required (cell linings are shed quite rapidly) ……..Work still needed to optimise the delivery! still needed to optimise the delivery! 20 Hurdles Hurdles in gene therapy…… •Efficiency- controlled by physical barrie...
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