A heterologous prime-boosting strategy with replicating Vaccinia virus vectors and plant-produced HIV-1 Gag/dgp41 virus-like particles

An Alternative Perfusion Approach for the Intensification of Virus-Like Particle Production in HEK293 Cultures

Virus-like particles (VLPs) have gained interest over the last years as recombinant vaccine formats, as they generate a strong immune response and present storage and distribution advantages compared to conventional vaccines. Therefore, VLPs are being regarded as potential vaccine candidates for several diseases. One requirement for their further clinical testing is the development of scalable processes and production platforms for cell-based viral particles. In this work, the extended gene expression (EGE) method, which consists in consecutive media replacements combined with cell retransfections, was successfully optimized and transferred to a bioreactor operating in perfusion. A process optimization using design of experiments (DoE) was carried out to obtain optimal values for the time of retransfection, the cell specific perfusion rate (CSPR) and transfected DNA concentration, improving 86.7% the previously reported EGE protocol in HEK293. Moreover, it was successfully implemented at 1.5L bioreactor using an ATF as cell retention system achieving concentrations of 6.8·10¹⁰ VLP/mL. VLP interaction with the ATF hollow fibers was studied via confocal microscopy, field emission scanning electron microscopy, and nanoparticle tracking analysis to design a bioprocess capable of separating unassembled Gag monomers and concentrate VLPs in one step.

The potential of plant systems to break the HIV-TB link

Tuberculosis (TB) and human immunodeficiency virus (HIV) can place a major burden on healthcare systems and constitute the main challenges of diagnostic and therapeutic programmes. Infection with HIV is the most common cause of Mycobacterium tuberculosis (Mtb), which can accelerate the risk of latent TB reactivation by 20-fold. Similarly, TB is considered the most relevant factor predisposing individuals to HIV infection. Thus, both pathogens can augment one another in a synergetic manner, accelerating the failure of immunological functions and resulting in subsequent death in the absence of treatment. Synergistic approaches involving the treatment of HIV as a tool to combat TB and vice versa are thus required in regions with a high burden of HIV and TB infection. In this context, plant systems are considered a promising approach for combatting HIV and TB in a resource-limited setting because plant-made drugs can be produced efficiently and inexpensively in developing countries and could be shared by the available agricultural infrastructure without the expensive requirement needed for cold chain storage and transportation. Moreover, the use of natural products from medicinal plants can eliminate the concerns associated with antiretroviral therapy (ART) and anti-TB therapy (ATT), including drug interactions, drug-related toxicity and multidrug resistance. In this review, we highlight the potential of plant system as a promising approach for the production of relevant pharmaceuticals for HIV and TB treatment. However, in the cases of HIV and TB, none of the plant-made pharmaceuticals have been approved for clinical use. Limitations in reaching these goals are discussed.