Lecture 25 part 2 26 The Origin of HIV Extra credit opportunity storycorps me Story Corps project Does HIV Cause AIDS HIV is the virus which causes the fatal disease of the immune system AIDS There are several critics who say AIDS is not caused by HIV infection How do we Prove HIV Causes AIDS Peter Duesberg AIDS Dissidents Proposed hypothesis that the various American and European diseases identified as AIDS are brought on by the long term consumption of recreational drugs and or AZT antiretroviral drug Immune system breakdown in Africa can be explained by malnutrition poor drinking water and infection overload Retroviruses like HIV must be harmless to survive because after reverse transcription from RNA to DNA they depend on cell division to replicate How do we prove a virus is a virus Koch s Postulates how does HIV follow this paradigm 1 Observe the microorganisms in the sick host 2 Grow the microorganism in pure culture 3 Inoculate the microbe into a healthy susceptible host and cause symptoms in the host Isolate the microbe in pure culture 4 Does HIV Really Cause AIDS 1 Plasma RNA concentration proportion of patients who developed AIDS within 6 years 2 People who developed AIDS within 6 years have a higher concentration of plasma RNA positive correlation 3 HIV isolated from virtually every patient with AIDS has been cultured or confirmed by molecular techniques PCR 4 Accidental exposure to HIV in lab workers resulted in development of AIDS no other risk factors present Animal models of human AIDS HIV is the only factor that predicts whether a person will develop AIDS disease found in individuals from diverse backgrounds Mbeki s Denial Saw an argument saying no correlation between HIV and AIDS he bought it Delayed health care and access to health care His delay of access lead to over 300 000 deaths that could have been prevented HIV 1 and HIV 2 1984 researchers discovered the primary causative viral agent the human immunodeficiency virus type 1 HIV 1 In 1986 a second type of HIV called HIV 2 was isolated from AIDS patients in West Africa Both HIV 1 and HIV 2 have the same modes of transmission and are associated with similar opportunistic infections and AIDS In persons infected with HIV 2 immunodeficiency seems to develop more slowly and tend to be milder HIV 2 infected individuals are less infectious early in the course of infection HIV 1 and HIV 2 also differ in geographic patterns of infection the US has few Origin of HIV 2 West Africa Where the habitat of the sooty mangabey is Origin of HIV 1 more infectious Central Africa Habitat of the reported HIV 2 cases Origins of HIV 1 and HIV 2 Chimpanzee 1999 HIV Origin Discovered almost identical to HIV 1 February 1999 a University of Alabama group found a type of SIVcpz that was The strain was identified in a frozen sample taken from a sub group of chimpanzees once common in west central Africa Researchers claimed this sample proved that chimpanzees were the source of HIV 1 The virus at some point crossed species from chimps to humans Theory Wild chimps simultaneously infected with 2 different SIV recombined to form a third virus that could be passed on to other chimps and was capable of infecting humans and causing AIDS The Origin of HIV These infected monkeys were infected with two different strains of SIV Scientists believe that chimps became infected with both strains of SIV after they hunted and killed the two smaller species of monkey The two different strains of SIV recombined to create the sivcpz that so closely resembled HIV How Did HIV Spread into Humans The Hunter Theory SIVcpz chimpanzee was transferred to humans as a result of chimps being killed and eaten or their blood getting into cuts or wounds on the hunter The Oral Polio Vaccine OPV Theory Virus was transferred through polio vaccine Kidney cells taken from local chimps infected with SIVcpz used to develop vaccine However February 2000 the Wistar Institute tested old vial of polio vaccine no HIV or chimpanzee SIV AND Macaque monkey kidney cells were used for OPV not cpz How did HIV Spread in Humans The Contaminated Needle Theory African healthcare professionals reused needles could have transferred HIV from hunters to population The Colonialism Theory Harsh labor camps lack of food poor sanitation weakened immune systems could lead to HIV if SIV infected chimp was eaten The Conspiracy Theory HIV is man made as bioweapon mainly to wipe out minorities and homosexuals Ignores the clear link between SIV and HIV or the fact that the virus has been identified in people as far back as 1959 Lack of genetic engineering technology available to create the virus at the time that AIDS first appeared Earliest Known Instances of HIV Infection 1 HIV in a plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of Congo 2 HIV found in tissue samples from an American teenager who died in St Louis in 1969 In fact trade 3 HIV found in tissue samples from a Norwegian sailor who died around 1976 HIV 1 might have been introduced into humans as early as 1905 1920 s Democratic Republic of Congo city Kinshasa may have cultivated the perfect virus genotype for an epidemic Transportation needles in colonial healthcare system sexual revolution and sex Kinshasa 1920 s 1960 s Urban growth Sex trade 5 men for every 1 woman Belgium backed railways Healthcare but no sterilized needles Origins and Timeline If HIV has been present in human populations since at least the 1920s and probably much earlier why did AIDS not become prevalent until the 1980 s The historical studies of HIV 1 indicate that the spread of the virus was initially quite slow The epidemic exploded in the 1950s and 1960s coincident with the end of colonial rule in Africa several civil wars the introduction of widespread vaccination programs with the deliberate or inadvertent reuse of needles and growth of large African cities the sexual revolution and increased travel by humans to and from Africa Given the roughly 10 year period from infection to progression to AIDS it was not until the 1970s that the symptoms of AIDS became prevalent in infected individuals in the United States and Europe HIV Subtypes HIV 1 Group N or Group M A B C D E F G H I J K and CRFs
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