A Coreceptor-Mimetic Peptide Enhances the Potency of V3-Glycan Antibodies

In vivo evolution of env in SHIV-AD8EO-infected rhesus macaques after AAV-vectored delivery of eCD4-Ig

eCD4-immunoglobulin (Ig) is an HIV entry inhibitor that mimics the engagement of both CD4 and CCR5 with the HIV envelope (Env) protein, a property that imbues it with remarkable potency and breadth. However, env is exceptionally genetically malleable and can evolve to escape a wide variety of entry inhibitors. Here we document the evolution of partial eCD4-Ig resistance in SHIV-AD8EO-infected rhesus macaques (RMs) treated with adeno-associated virus vectors encoding eCD4-Ig. In one RM, setpoint viremia plateaued at 1,000 vRNA copies/mL, despite concomitant serum concentrations of eCD4-Ig in the 60-110 μg/mL range, implying that the virus had gained partial eCD4-Ig resistance. Env mutations occurring prominently in this animal were cloned and further characterized. Three of these mutations (R315G, A436T, and G471E) were sufficient to confer substantial resistance to eCD4-Ig-mediated neutralization onto the parental Env, accompanied by a marked loss of viral fitness. This resistance was not driven by decreased CD4 affinity, subverted sulfopeptide mimicry, changes to co-receptor tropism, or by a gain of CD4 independence. Rather, our data argue that the Env evolving in this animal attained eCD4-Ig resistance by decreasing triggerability, stabilizing the triggered state, and changing the nature of its relationship to the host CD4.

Endodomain truncation of the HIV-1 envelope protein improves the packaging efficiency of pseudoviruses

HIV-1 remains one of the most devastating infectious pathogens without available vaccines. A valid neutralization assay using multiple representative virus strains is prerequisite for antibody response analysis in HIV-1 vaccine development, where HIV pseudoviruses (PsVs) commonly serve as surrogate agents for the authentic HIV, offering a safer manipulation in Biosafety Level 2+. However, PsV production is of low efficiency and is unstable in this field. Here, we optimize PsV production conditions via the use of alternative host cells, packaging ratios and gene truncation. We show that a 153-aa truncation of the endodomain substantially enhances the packaging efficiency of HIV PsVs, providing 4 to 25 times higher infection titers than the full-length Env. Further, we obtained a robust HIV-1 PsV panel covering 12 representative global strains for neutralization assay testing. This work sheds light on how to optimize HIV PsV packaging, and provides functional insight into the cytoplasmic domain of HIV-1.

Antibody Conjugates for Targeted Therapy Against HIV-1 as an Emerging Tool for HIV-1 Cure

Although advances in antiretroviral therapy (ART) have significantly improved the life expectancy of people living with HIV-1 (PLWH) by suppressing HIV-1 replication, a cure for HIV/AIDS remains elusive. Recent findings of the emergence of drug resistance against various ART have resulted in an increased number of treatment failures, thus the development of novel strategies for HIV-1 cure is of immediate need. Antibody-based therapy is a well-established tool in the treatment of various diseases and the engineering of new antibody derivatives is expanding the realms of its application. An antibody-based carrier of anti-HIV-1 molecules, or antibody conjugates (ACs), could address the limitations of current HIV-1 ART by decreasing possible off-target effects, reduce toxicity, increasing the therapeutic index, and lowering production costs. Broadly neutralizing antibodies (bNAbs) with exceptional breadth and potency against HIV-1 are currently being explored to prevent or treat HIV-1 infection in the clinic. Moreover, bNAbs can be engineered to deliver cytotoxic or immune regulating molecules as ACs, further increasing its therapeutic potential for HIV-1 cure. ACs are currently an important component of anticancer treatment with several FDA-approved constructs, however, to date, no ACs are approved to treat viral infections. This review aims to outline the development of AC for HIV-1 cure, examine the variety of carriers and payloads used, and discuss the potential of ACs in the current HIV-1 cure landscape.