The main hindrance to develop antiviral therapies and effective vaccines for HIV-1 is the high variability of the virus. Recombination is a major mechanism that is responsible for the rapid diversification of HIV-1 population. Recombination between different subtypes of HIV-1 generates intersubtype recombinants. These intersubtype recombinants can also recombine with HIV-1 of the same or different subtypes or with other recombinants to generate more complex recombinants. Intersubtype recombinants emerge in almost every region of the world where more than one HIV-1 subtype is present. Currently, 49 HIV-1 circulating recombinant forms (CRFs) and a large number of unique recombinant forms (URFs) have been identified. These CRFs and URFs accounted for approximately 20% of global infections and they continue to play an increasingly important role in shaping the AIDS pandemic. iVly current research focuses on the mechanisms and pathogenomics of HIV-1 replication and intersubtype recombination. In this application, we continue our study on understanding the molecular mechanisms for generating HIV-1 intersubtype recombinants with biological advantages. Our long-term goal is to elucidate the elements in the viral genome that affect replication fitness of a HIV-1 recombinant. These viral elements represent new potential targets for blocking or enhancing recombination that can affect the continuous replication of HIV-1 in the host. The objectives of this application are to characterize the molecular structures and the replication fitness of HIV-1 intersubtype recombinants generated in vivo. The central hypothesis is that newly generated HIV-1 intersubtype recombinants have an array of replication fitness and there is a finite window for HIV-1 replication fitness allowing the recombinants to continue to replicate in the host.
The Specific Aims are to 1) reveal the diversity of HIV-1 intersubtype recombinants in vivo, 2) characterize the replication fitness of HIV-1 intersubtype recombinants and 3) define the selection pressure for generating HIV-1 intersubtype recombinants with biological advantages. We expect our work will enhance our knowledge on the molecular mechanisms that generate HIV-1 variations and new HIV-1 recombinant strains.
The proposed research is relevant to public health because the identified viral elements that determine replication fitness may represent new targets for developing strategies to prevent the continuous replication of HIV-1 in the human hosts.