HIV-Nutr116+2010+Nov+short

HIV-Nutr116+2010+Nov+short - HIV, AIDS and Nutrition...

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HIV, AIDS and Nutrition Charles B. Stephensen, Ph.D. USDA Western Human Nutrition Research Center UC Davis Department of Nutrition charles.stephensen@ars.usda.gov
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HIV, AIDS and Nutrition The virus – HIV The disease – AIDS Epidemiology Pathogenesis and clinical course Treatment Nutrition Impact of infection on nutritional status Impact of nutrition on course of disease Nutritional support
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HIV - The Virus
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Scanning electron micrograph of HIV budding from lymphocyte. Public Health Image Library Human Immunodeficiency Virus: The cause of AIDS HIV is a retrovirus. Retroviruses were first of interest to virologists because they convert their RNA genome into DNA (to incorporate into host genomic DNA) using the reverse transcriptase (RT) enzyme. Transmission electron micrograph of purified HIV. Public Health Image Library HIV infects cells by binding to its principal cell-surface receptor, CD4, as well as co-receptors, primarily CCR5 and CXCR4. The virus replicates within infected cells and new, infectious virus buds from the cell surface.
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X X X X X HIV replication is error-prone. Thus point mutations are frequent, allowing rapid evolution under selective pressure . Such pressure may come from cross-species “jumps”, the host immune response or anti-retroviral drugs.
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HIV diversity within individuals Individuals infected with HIV develop many variant genotypes over the course of their infection, although one genotype is usually dominant at a time. These abrupt switches presumably result from an increased fitness that allows the new genotype to “escape” from the host immune response or antiretroviral therapy. Origins of HIV There are 2 strains of HIV. HIV-1 is found world-wide , HIV- 2 only in West Africa. Both strains evolved from one of many simian immunodeficiency viruses (SIV) that infect different primate species in Africa. HIV-1 jumped from chimpanzees to humans several times in Central or West Africa, probably between 1910 and 1940. HIV-2 originated from sooty mangabees in West Africa. Rambaut et al., January 2004 SIV as a zoonotic infection The HIV-2 and SIV strains from the same region of West Africa are quite similar and suggest a continued spread from monkeys to humans as a result of hunting primates as a source of food. World-wide distribution West Africa West Africa West Africa West Africa Dendrogram The horizontal distance from a virus (end of a branch) to another virus (via a branch- point) indicates how closely the viruses are related, based on genomic sequence comparisons.
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HIV Infection - Epidemiology
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33 million people worldwide with HIV as of 2007 Most prevalent in African countries 1.1 million in U.S. Majority of new infections in minority,
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HIV-Nutr116+2010+Nov+short - HIV, AIDS and Nutrition...

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