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HIV-1 envelope glycoproteins (Envs) mediate viral entry and represent a target of choice for small molecule inhibitors. One of them, temsavir (BMS-626529) prevents the interaction of the host cell receptor CD4 with Env by binding the pocket under the β20–β21 loop of the Env subunit gp120. Along with its capacity to prevent viral entry, temsavir stabilizes Env in its "closed" conformation. We recently reported that temsavir affects glycosylation, proteolytic processing, and overall conformation of Env. Here, we extend these results to a panel of primary Envs and infectious molecular clones (IMCs), where we observe a heterogeneous impact on Env cleavage and conformation. Our results suggest that the effect of temsavir on Env conformation is associated with its capacity to decrease Env processing. Indeed, we found that the effect of temsavir on Env processing affects the recognition of HIV-1-infected cells by broadly neutralizing antibodies and correlates with their capacity to mediate antibody-dependent cellular cytotoxicity (ADCC). [ABSTRACT FROM AUTHOR]

HIV-1 envelope glycoprotein (Env) interacts with cellular receptors and mediates virus entry into target cells. Blocking Env-receptor interactions represents an effective interventional strategy for developing HIV-1 entry inhibitors. We previously designed a panel of CD4-linker-DC-SIGN (CLD) constructs by fusing the extracellular CD4 and DC-SIGN domains with various linkers. Such CLDs produced by the prokaryotic system efficiently inhibited HIV-1 infection and dissemination in vitro and ex vivo. In this study, following the construction and identification of the most promising candidate with a linker of 8 Gly4Ser repeats (named CLD), we further designed an improved form (named CLDmut) by back mutating Cys to Ser at amino acid 60 of CD4. Both CLD and CLDmut were produced in mammalian (293F) cells for better protein translation and modification. The anti-HIV-1 activity of CLD and CLDmut was assessed against the infection of a range of HIV-1 isolates, including transmitted and founder (T/F) viruses. While both CLD and CLDmut efficiently neutralized the tested HIV-1 isolates, CLDmut demonstrated much higher neutralizing activity than CLD, with an IC50 up to one log lower. The neutralizing activity of CLDmut was close to or more potent than those of the highly effective HIV-1 broadly neutralizing antibodies (bNAbs) reported to date. Findings in this study indicate that mammalian cell-expressed CLDmut may have the potential to be used as prophylaxis or/and therapeutics against HIV-1 infection. [ABSTRACT FROM AUTHOR]

Broadly neutralizing monoclonal antibodies (bNAbs) against conserved domains in the influenza hemagglutinin are in clinical trials. Several next generation influenza vaccines designed to elicit such bNAbs are also in clinical development. One of the common features of the isolated bNAbs is the use of restricted IgVH repertoire. More than 80% of stem-targeting bNAbs express IgVH1-69, which may indicate genetic constraints on the evolution of such antibodies. In the current study, we evaluated a panel of influenza virus bNAbs in comparison with HIV-1 MAb 4E10 and anti-RSV MAb Palivizumab (approved for human use) for autoreactivity using 30 normal human tissues microarray and human protein (>9000) arrays. We found that several human bNAbs (CR6261, CR9114, and F2603) reacted with human tissues, especially with pituitary gland tissue. Importantly, protein array analysis identified high-affinity interaction of CR6261 with the autoantigen "Enhancer of mRNA decapping 3 homolog" (EDC3), which was not previously described. Moreover, EDC3 competed with hemagglutinin for binding to bNAb CR6261. These autoreactivity findings underscores the need for careful evaluation of such bNAbs for therapeutics and stem-based vaccines against influenza virus. [ABSTRACT FROM AUTHOR]