The Influence of CCL3L1 Gene- Containing Segmental Duplications on HIV-1/AIDS Susceptibility Gonzalez et al. Mar 4, 2005 :307 Science Presenter: Braydon Burgess Dept. Of Pathology and Laboratory Medicine, Masters Program

Estimated number of adults and children living with HIV by region, 1985— Caribbean North Africa & Middle East Eastern Europe & Central Asia Western and Central Europe & North America Latin America Asia Sub-Saharan Africa Number of people living with HIV Millions Source: UNAIDS/WHO AIDS Epidemic Update, Dec 2004

HIV Epidemiology People newly infected with HIV in 2004 Total4.9 million (4.3 – 6.4 million) AIDS deaths in 2004 Total3.1 million (2.8 – 3.5 million)

Institutional spending for HIV and AIDS 1996−2002 (US$ disbursements in millions) ,000 1,500 2,000 2,500 3, Domestic Private UN System Bilateral US$ millions Source: UNAIDS Resource Tracking Consortium 2004 Report on the Global AIDS Epidemic (Fig 37)

Human Immunodeficiency Virus-1 Transmission: Horizontal: Adult  Adult Vertical: Mother  Child Cell Binding: Host Receptor: CD4 Co-receptor: CCR5 Membrane fusion Viral replication & cell death

Background CD4 Cell signalling molecule Cell signalling molecule A defining feature of T-helper cells A defining feature of T-helper cells The REQUIRED receptor for HIV entry The REQUIRED receptor for HIV entry Chemokine Receptor 5 (CCR5) Highly expressed on memory T-cells Highly expressed on memory T-cells Major co-receptor for HIV entry Major co-receptor for HIV entry Chemokine Ligand 3-like-1 (CCL3L1) Released following immunological challenge Released following immunological challenge CCL3L1 strongest ligand for CCR5 CCL3L1 strongest ligand for CCR5 Known to be a dominant suppressor of HIV Known to be a dominant suppressor of HIV

Background CCL3L1 gene contained on a hotspot for segmental duplication Copy # was known to be variable in human populations Gene dose is proportionate to chemokine levels

Research Question Can segmental duplications causing dosage effects of host defence genes be associated with phenotypic effects in vivo? Do extra gene copies of CCL3L1 decrease HIV susceptibility?

Study Populations Human Diversity Cell Line Panel Tissue samples from ancestral populations Tissue samples from ancestral populations Wilford Hall Medical Centre (WHMC) Cohort of 1330 HIV + USAF Military Personnel & matched controls Cohort of 1330 HIV + USAF Military Personnel & matched controlsNon-WHMC HIV - civilian cohort, 1300 individuals matched to the WHMC cohort HIV - civilian cohort, 1300 individuals matched to the WHMC cohort Argentinean Children Composed of 450 HIV + children and controls all exposed perinatally to HIV Composed of 450 HIV + children and controls all exposed perinatally to HIV

Q: What is the Global Variation in CCL3L1 Copy # Conclusion: CCL3L1 gene copy # is variable between populations but similarly dispersed within populations. ANOVA indicates that geography accounts for 35% of copy# variance.

Q: Is CCL3L1 Copy # Associated with HIV Acquisition Conclusion: There is a significant correlation between copy # and HIV prevalence in all populations Each CCL3L1 copy decreases risk of HIV infection by 4.5%-10.5%

Clinical Answer Biochemical Answer Q: Does CCL3L1 Copy # Affect Progression to AIDS Conclusion: 1: Progression to AIDS is accelerated in low copy # individuals. 2: Low CCL3L1 copy # elevates CCR5 exposure, increasing accessibility to HIV 3: Low copy # is associated with a poorer clinical prognosis Epidemiology Answer

Q: Is Copy # an Absolute Determinant of HIV Progression Conclusion: Copy # in the context of genetic background determines which copy #s are beneficial

Q: Are Copy # Phenotypes Affected by Genetic Interactions Conclusion: CCL3L1 copy # effect is stronger than CCR5 genotype and copy # enhances CCR5 defects

CCR5 and CCL3L1 Are Major Contributors to HIV Susceptibility

Summary CCL3L1 copy number shows inter- and intra- population variation (0-10+ copies) CCL3L1 copy # is positively associated with a dose-dependant protection from HIV acquisition and progression to AIDS. Low CCL3L1 copy # and detrimental CCR5 mutations have harmful interactions and account for variability in disease progression (~30%) and in transmission (~20-40%)