Simian-Human immunodeficiency viruses expressing chimeric subtype B/C Vpu proteins demonstrate the importance of the amino terminal and transmembrane domains in the rate of CD4(+) T cell loss in macaques

The Early Results of Vertebral Pathological Compression Fracture of Extra- nodal Lymphoma with HIV-positive Patients Treated by Percutaneous Kyphoplasty

BACKGROUND

Vertebral pathological compression fracture involving extra-nodal lymphoma impacts negatively on the quality of life of HIV-positive patients. The choice of a safe and effective approach to palliative care in this condition remains a challenge.

OBJECTIVE

The purpose of this study was to investigate the safety and efficacy of percutaneous kyphoplasty (PKP) in the treatment of vertebral pathological compression fracture of extra-nodal lymphoma in HIV-positive patients.

METHODS

A retrospective analysis, from January 2016 to August 2019, was performed on 7 HIVpositive patients, 3 males and 4 females, with extra-nodal lymphoma with a vertebral pathological compression fracture. The patients were treated using percutaneous kyphoplasty in our hospital. Preoperative assessment of the patients was conducted regarding their hematological profile, biochemical indicators, liver and kidney function, blood coagulation function, CD4+T lymphocyte count and viral load. Subsequently, the patients were placed on highly active antiretroviral therapy (HAART) and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (RCHOP) regimen. Besides, antibiotics, nutritional support and immune-modulating drugs were also administered, rationally. Postoperatively, the height of the anterior edge of the injured vertebrae, Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) values were evaluated. Patients were also monitored for any complications related to the operation.

RESULTS

The average CD4+T cell count for the patients was 164 (range 114 ~247 / ul), while the viral load was 26,269 (range 5,765 ~82,321 copies/ul). All patients received nutritional and immune support and registered significant improvements in the levels of ALB and Hb (P<0.05). In all cases, the operation was uneventful with neither cement leakage nor toxic reactions observed. Similarly, no opportunistic infections, other complications or deaths were reported. The height of the anterior vertebral body and the ODI score of the injured vertebrae were significantly improved immediately after surgery (P<0.05). Compared to the preoperative VAS (7.71±1.11), postoperative values were significantly reduced immediately after surgery (3.85±0.90) and at 2 weeks, 1 month and 6 months post-surgery: 2.71±0.76, 3.29±1.11, and 4.00±0.82, respectively (P<0.01).

CONCLUSION

Supported with appropriate perioperative treatment measures, PKP is safe and effective in the treatment of pathological vertebral compression fracture due to extra-nodal lymphoma in HIV-positive patients.

The Envelope Cytoplasmic Tail of HIV-1 Subtype C Contributes to Poor Replication Capacity through Low Viral Infectivity and Cell-to-Cell Transmission

The cytoplasmic tail (gp41CT) of the HIV-1 envelope (Env) mediates Env incorporation into virions and regulates Env intracellular trafficking. Little is known about the functional impact of variability in this domain. To address this issue, we compared the replication of recombinant virus pairs carrying the full Env (Env viruses) or the Env ectodomain fused to the gp41CT of NL4.3 (EnvEC viruses) (12 subtype C and 10 subtype B pairs) in primary CD4+ T-cells and monocyte-derived-macrophages (MDMs). In CD4+ T-cells, replication was as follows: B-EnvEC = B-Env>C-EnvEC>C-Env, indicating that the gp41CT of subtype C contributes to the low replicative capacity of this subtype. In MDMs, in contrast, replication capacity was comparable for all viruses regardless of subtype and of gp41CT. In CD4+ T-cells, viral entry, viral release and viral gene expression were similar. However, infectivity of free virions and cell-to-cell transmission of C-Env viruses released by CD4+ T-cells was lower, suggestive of lower Env incorporation into virions. Subtype C matrix only minimally rescued viral replication and failed to restore infectivity of free viruses and cell-to-cell transmission. Taken together, these results show that polymorphisms in the gp41CT contribute to viral replication capacity and suggest that the number of Env spikes per virion may vary across subtypes. These findings should be taken into consideration in the design of vaccines.

Involvement of a C-terminal motif in the interference of primate lentiviral Vpu proteins with CD1d-mediated antigen presentation

The HIV-1 accessory protein Vpu is emerging as a critical factor for viral evasion from innate immunity. We have previously shown that the Vpu proteins of two HIV-1 group M subtype B strains (NL4-3 and BaL) down-regulate CD1d from the surface of infected dendritic cells (DCs) and inhibit their crosstalk with the innate invariant natural killer T (iNKT) cells. In the present study, we have investigated the ability of a comprehensive set of primate lentiviral Vpu proteins to interfere with CD1d-mediated immunity. We found that CD1d down-regulation is a conserved function of Vpu proteins from HIV-1 groups M, O and P as well as their direct precursors SIVcpzPtt and SIVgor. At the group M subtype level, subtype C Vpu proteins were significantly weaker CD1d antagonists than subtype B Vpu proteins. Functional characterization of different mutants and chimeras derived from active subtype B and inactive subtype C Vpu proteins revealed that residues in the cytoplasmic domain are important for CD1d down-regulation. Specifically, we identified a C-terminal APW motif characteristic for group M subtype B Vpu proteins necessary for interference with CD1d surface expression. These findings support the notion that Vpu plays an important role in lentiviral evasion from innate immunity.

A comparative mutational analysis of HIV-1 Vpu subtypes B and C for the identification of determinants required to counteract BST-2/Tetherin and enhance viral egress

We have undertaken a genetic strategy to map Vpu regions necessary for BST-2 antagonism and viral egress. This approach is based on our identification of an egress-defective Vpu variant encoded by an HIV-1 subtype C strain. We constructed a series of chimeric Vpu molecules made from the Vpu C variant and Vpu B from a standard laboratory strain. The TM domain from the inactive Vpu C, which contains multiple non-conserved residues, was responsible for a significant decrease in egress activity and BST-2 downregulation, confirming the functional importance of the Vpu TM domain. However, for complete inactivation, both the N-terminus and TM domain from the inactive Vpu C molecule were required, suggesting a new role for the Vpu N-terminus. In addition, determinants in the C-terminus of Vpu B that may be involved in efficient TGN accumulation were also necessary for enhanced viral egress but are missing or non-functional in Vpu C.