Nucleic Aptamer Selection against CCR5 for the Prevention of HIV Pathogenesis

HIV, the human immunodeficiency virus, progressively weakens the body’s internal defense system by infecting cells vital to the human immune system such as helper T-Cells, macrophages, and dendritic cells (Cunningham, 2010). HIV progresses to AIDS, the acquired immunodeficiency syndrome, a state of extremely low immune system effectiveness that makes the body susceptible to infections that can result in death. A retrovirus, HIV binds to specific receptor and coreceptor proteins on helper T-cells, macrophages, and dendritic cells in order to inject the cells with its virulent RNA.

C-C Chemokine Receptor type 5, CCR5, is the main coreceptor protein used by M-tropic strains of the HIV type 1 (HIV-1) and type 2 (HIV-2). Humans who exhibit a mutation in the CCR5 gene coding region produce a nonfunctional, truncated protein that is not transported to the surface of the cell membrane (Blanpain et al, 2002). CCR5 therefore plays a crucial role in HIV pathogenesis, for without its functional existence, HIV cannot infect its target cells.

A multistep approach is proposed that seeks to prevent the binding of HIV strains to the coreceptor CCR5, thus preventing HIV infection and pathogenesis. RNA molecules that are developed to bind specific targets, called aptamers, have many diagnostic and therapeutic uses and are a promising means of inhibiting the binding of HIV to CCR5. Much like an allosteric or competitive inhibitor, an aptamer that binds tightly to CCR5 will alter its three-dimensional configuration and thus impede it from acting as a functional coreceptor to HIV. Developing and isolating an aptamer against CCR5 will provide an alternative to existing receptor antagonists and provide a novel way of preventing and treating infections caused by M-tropic strains of HIV.

Specific Aim 1: Selection of RNA Aptamers against CCR5

CCR5 is a coreceptor crucial to HIV pathogenesis. It has been shown that a mutation in the CCR5 gene results in HIV immunity (Tang, 2003) and that using CCR5 receptor antagonists prevent the binding of HIV to CCR5, inhibiting HIV infection (Pulley, 2007). Thus, the development of nucleic aptamers against CCR5 will serve as another means of preventing the binding of HIV to the crucial protein CCR5 and inhibit infection altogether by acting as an entry inhibitor.

CCR5 can be acquired from Abcam (www.abcam.com) for $160 per 100 ug. The catalog number is ab95861. A more useful, yet more expensive form of CCR5 tagged with His protein can be acquired from Abnova for $249 per 2 ug. The catalog number for Abnova is H00001234-P01.

Works cited

Blanpain, C.; Libert, F.; Vassart, G.; Parmentier, M. (2002). ”CCR5 and HIV infection.” Receptors and Channels. 2002; 8(1):19-31.

Cunningham, A.; Donaghy, H.; Harman, A.; Kim, M.; Turville, S. (2010). "Manipulation of dendritic cell function by viruses". Current opinion in microbiology 13 (4): 524–529Wiki first part

Pulley, Shon (2007). "CCR5 antagonists: from discovery to clinical efficacy". In Neote, Kuldeep; Letts, Gordon L.; Moser, Bernhard. Chemokine Biology — Basic Research and Clinical Application. 2. Birkhauser Basel. pp. 145–163.

Tang, J. and Kaslow, R. A. (2003). "The impact of host genetics on HIV infection and disease progression in the era of highly active antiretroviral therapy". AIDS 17 (Suppl 4): S51–S60

********************By: Juan Herrejon**********************

*Juan could not post on the blog for some reason so I helped him :)*