VLPs containing modified HIV Env have been developed for an AIDS vaccine, capable of inducing cellular and humoral immune responses; including neutralizing activities.
- VLPs are safer than live replicating vectored vaccines because of their lack of infectivity, allowing for use in immunocompromised patients.
- HIV VLPs extract both arms of immunity and create immune responses at local and distal, mucosal surfaces.
One of the major obstacles in developing an effective AIDS vaccine is the difficulty in inducing antibodies that are broadly reactive against many HIV-1 isolates. In particular, immune cells have to be able to recognize the HIV virus, in order for immunity to exist. However, extensive glycosylations and highly variable loops enable HIV-1 to evade host immune recognition by shielding some conserved neutralizing epitopes, such as regions of HIV-1 Env that bind to cellular receptors and coreceptors.
Dr. Compans, with other researchers at Emory, have demonstrated that substitutions of HIV-1 Env sequences with glycoproteins from other enveloped viruses (MMTV, LFV, BV, and influenza virus) would increase the level of Env incorporation into corresponding virus particles. Using electron microscopy researchers were able to confirm that the spherical VLP's had protruding ENV proteins on their cell surface. Studies have also shown that HIV chimeric Env-containing VLP's posses a conformation for the cavity-laden CD4-gp120 interface of HIV, allowing for effective antibody binding to virus cells The immune system is then able to recognize virus infected cells and can mount an immunological reaction to prevent disease.