Complex decay dynamics of HIV virions, intact and defective proviruses, and 2LTR circles following initiation of antiretroviral therapy.

In persons living with HIV-1 (PLWH) who start antiretroviral therapy (ART), plasma virus decays in a biphasic fashion to below the detection limit. The first phase reflects the short half-life (<1 d) of cells that produce most of the plasma virus. The second phase represents the slower turnover (t1/2 = 14 d) of another infected cell population, whose identity is unclear. Using the intact proviral DNA assay (IPDA) to distinguish intact and defective proviruses, we analyzed viral decay in 17 PLWH initiating ART. Circulating CD4+ T cells with intact proviruses include few of the rapidly decaying first-phase cells. Instead, this population initially decays more slowly (t1/2 = 12.9 d) in a process that largely represents death or exit from the circulation rather than transition to latency. This more protracted decay potentially allows for immune selection. After ∼3 mo, the decay slope changes, and CD4+ T cells with intact proviruses decay with a half-life of 19 mo, which is still shorter than that of the latently infected cells that persist on long-term ART. Two-long-terminal repeat (2LTR) circles decay with fast and slow phases paralleling intact proviruses, a finding that precludes their use as a simple marker of ongoing viral replication. Proviruses with defects at the 5' or 3' end of the genome show equivalent monophasic decay at rates that vary among individuals. Understanding these complex early decay processes is important for correct use of reservoir assays and may provide insights into properties of surviving cells that can constitute the stable latent reservoir.

The Effect of Optic Nerve Sheath Fenestration on Intraocular Pressure in Patients With Idiopathic Intracranial Hypertension.

BACKGROUND: To evaluate the change in intraocular pressure (IOP) in patients with idiopathic intracranial hypertension (IIH) who underwent optic nerve sheath fenestration (ONSF) and to determine if radiographic evidence of posterior scleral or globe indentation influenced IOP. METHODS: This is a retrospective analysis of IOP in IIH patients who underwent ONSF. The study included all patients from September 2010 to March 2018 operated on by a single surgeon (R.M.). IOPs preoperatively and postoperatively were recorded along with the acetazolamide dosage and whether there was evidence of posterior scleral or globe indentation on preoperative MRI. RESULTS: A total of 29 patients (35 eyes) with IIH underwent ONSF. The average reduction in IOP among all patients was 1.24 mm Hg (P = 0.0218), but this increased to 2.69 mm Hg (P = 0.004) in patients who were maintained on the same dosage of acetazolamide in the preoperative and postoperative period. Furthermore, the reduction in IOP in those with posterior scleral or globe indentation was 2.5 mm Hg (P = 0.0095). When the perioperative period was evaluated, the mean decrease in IOP was 1.83 mm Hg (P = 0.0217). CONCLUSIONS: Reducing the cerebral spinal fluid pressure (CSFP) at the level of the intraorbital optic nerve through an ONSF can slightly reduce the IOP. In those with evidence of posterior globe or scleral indentation/flattening, the reduction in IOP was higher, which supports the theory that CSF pressure indents the globe and leads to an increase in IOP. Although these changes in IOP are small, this study provides further evidence for a connection between IOP and CSFP.

Snapshots of a protein folding intermediate.

We have investigated the folding dynamics of Thermus thermophilus cytochrome c(552) by time-resolved fluorescence energy transfer between the heme and each of seven site-specific fluorescent probes. We have found both an equilibrium unfolding intermediate and a distinct refolding intermediate from kinetics studies. Depending on the protein region monitored, we observed either two-state or three-state denaturation transitions. The unfolding intermediate associated with three-state folding exhibited native contacts in ß-sheet and C-terminal helix regions. We probed the formation of a refolding intermediate by time-resolved fluorescence energy transfer between residue 110 and the heme using a continuous flow mixer. The intermediate ensemble, a heterogeneous mixture of compact and extended polypeptides, forms in a millisecond, substantially slower than the ∼100-µs formation of a burst-phase intermediate in cytochrome c. The surprising finding is that, unlike for cytochrome c, there is an observable folding intermediate, but no microsecond burst phase in the folding kinetics of the structurally related thermostable protein.