The antiviral restriction of a chimeric APOBEC3A protein.
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: In this proposal, we will study the potential use of a new protein based on the fusion between a cellular protein that has effects against HIV-1 virus (APOBEC3A) and a viral protein that is incorporated into new viral particles (Vpr). APOBECs are human proteins that cause mutations in the HIV-1 viral genome and these mutations destroy the virus when it tries to infect new cells in humans. The antiviral effects of APOBEC proteins are mediated by their ability to modify the viral DNA composition. High levels of mutations caused by APOBECs can inactivate important genes of HIV-1 and block the infection of new cells. However, HIV-1 produces another protein called Vif that can inactivate deleterious effects of human APOBEC proteins. APOBEC3A (A3A) belongs to the APOBEC family of proteins. This protein is able to cause mutations in the viral DNA; however, it’s not able to block the infection. Here, we constructed a new A3A protein by fusing it with Vpr. This new protein (Vpr.A3A) is able to block the infection. Also, this new protein can not be inactivated by Vif. The long term objectives of this proposal are to evaluate the use of this Vpr.A3A chimera in therapeutic strategies against HIV-1/AIDS. The general strategy is to understand the molecular mechanism involved in this new antiviral effect of Vpr.A3A. Three specific aims will be addressed for this proposal. In the first specific aim we will determine which factors render the Vpr.A3A fusion protein able to block HIV infection, while the original A3A can not. Vpr is found into the viral core in close proximity to the viral genome. We hypothesized that the fusion with Vpr is responsible to carry the A3A in large quantities to the viral core while escaping Vif degradation. Vpr incorporation into the viral particles is mediated by the interaction with others viral proteins (p6). To determine the role of Vpr, we will block incorporation of this chimera by deleting the sequences that are responsible for interaction with p6 and evaluate if this modification can interfere in antiviral effects of Vpr.A3A. We will also compare the incorporation rates of Vpr.A3A and the original A3A in viral cores and the formation of complexes than can inhibit APOBEC proteins. For the second specific aim, we will evaluate the antiviral effect of the Vpr.A3A chimera against others viruses such SIV, MLV, MMTV and HERV-Kcon. To evaluate each particular virus, they will be produced in the presence of the Vpr.A3A fusion protein and the infectivity of these viruses will be evaluated in newly infected cells. In the last aim we will determine the utility of this Vpr.A3A chimera to block the infection of incoming virus. For this aim, we will introduce the DNA coding region of Vpr.A3A into a human cell line to produce cells that express stably this chimera. These new cells will be challenged with HIV-1 to evaluate if the production of Vpr.A3A in the recipient cells can protect theirs of viral infection. Our studies will not only reveal new aspects of targeting of APOBEC proteins into viral particles, but suggest the use of Vpr.A3A fusion protein as new genetic therapy in AIDS.