As of 2011, the UNAIDS report on the global AIDS epidemic indicated that 34 million people are living with HIV. Regionally, the number of infected individuals in the USA and Canada is 1.4 million with 51,000 new cases being documented every year. Furthermore, AIDS-related causes claim the lives of nearly 20,000 people in the USA annually and HIV-associated neurocognitive disorders are diagnosed in up to 47 percent of patients despite the use of highly active antiretroviral therapy. Recently, the concept of exosomes acting as vehicles of intercellular communication has opened up new avenues of study regarding host-pathogen interactions and viral spread. Another emerging field regarding viral infections is that of the RNA interference pathway which generates miRNAs that guide effector complexes to complimentary sequences in mRNA or DNA, thereby suppressing gene expression. Moreover, our lab, as well as others, has identified miRNAs derived from the TAR element of integrated provirus in long-term infections. While the concept of HIV-1 viral miRNAs remains controversial, labs concluding that HIV-1 doesn't encode miRNAs have examined short-term infections as opposed to the more biologically relevant long-term infections. Furthermore, our initial data shows viral miRNAs derived from HIV-1 TAR are packaged and secreted from infected cells through exosomes. Our long term goal is to understand the role played by exosomes from HIV-1 infected cells in regulating host-virus interactions. The primary objective of the current proposal is to elucidate the mechanisms by which HIV altered exosomes effect uninfected cells of CNS origins, and assist in viral spread. We hypothesize that viral miRNAs within exosomes of infected cells alter recipient cells by impacting regulation signal transduction and gene expression, as well as viral spread. The rationale for our hypothesis includes our data showing viral miRNAs in culture supernatants and patient sera suggesting the miRNAs are in a protected environment. Moreover, we've shown that exosomes from infected cells can exert functional influences on naive bystander cells and make them more susceptible to HIV infection. However, our current understanding of the functionality of HIV-altered exosomes is limited, resulting in a gap of knowledge regarding exosomal mechanisms that contribute to viral pathogenesis in the CNS. To test our hypothesis we propose the following aims: 1) Examine the altered composition and mechanisms of exosome manipulation in infected primary cells, and validate the functionality of exosomes on recipient cells of CNS origins 2) Test the effects of exosomes on HIV-1 replication in human MDMs within the brain using humanized animals. The expected outcomes of these studies includes elucidation of altered exosome composition and viral miRNA influences on signal transduction, gene expression and increased viral susceptibility of naive recipient cells of the CNS. Our in vivo experiments, in combination with validation of decreased exosome biogenesis following exosome inhibitor treatment, will establish a strong correlation between circulating exosomes and infection-associated phenotypes in the CNS.
As of 2011, 34 million people are living with HIV. Regionally, HIV infected individuals in the USA and Canada number 1.4 million with 51,000 new cases annually. AIDS-related causes also kill nearly 20,000 people in the US per year and HIV-associated neurocognitive disorders (HAND) are diagnosed nearly 47 percent of patients.
|Ahsan, Noor A; Sampey, Gavin C; Lepene, Ben et al. (2016) Presence of Viral RNA and Proteins in Exosomes from Cellular Clones Resistant to Rift Valley Fever Virus Infection. Front Microbiol 7:139|
|Sampey, Gavin C; Saifuddin, Mohammed; Schwab, Angela et al. (2016) Exosomes from HIV-1-infected Cells Stimulate Production of Pro-inflammatory Cytokines through Trans-activating Response (TAR) RNA. J Biol Chem 291:1251-66|