Derivation of non-infectious envelope proteins from virions isolated from plasma negative for HIV antibodies.

Natural membrane-bound HIV-1 envelope proteins (mHIVenv) could be used to produce an effective subunit vaccine against HIV infection, akin to effective vaccination against HBV infection using the hepatitis B surface antigen. The quaternary structure of mHIVenv is postulated to elicit broadly neutralizing antibodies protective against HIV-1 transmission. The founder virus transmitted to infected individuals during acute HIV-1 infection is genetically homogeneous and restricted to CCR5-tropic phenotype. Therefore, isolates of plasma-derived HIV-1 (PHIV) from infected blood donors while negative for antibodies to HIV proteins were selected for expansion in primary lymphocytes as an optimized cell substrate (OCS). Virions in the culture supernatants were purified by removing contaminating microvesicles using immunomagnetic beads coated with anti-CD45. Membrane cholesterol was extracted from purified virions with beta-cyclodextrin to permeabilize them and expel p24, RT and viral RNA, and permit protease-free Benzonase to hydrolyze the residual viral/host DNA/RNA without loss of gp120. The resultant mHIVenv, containing gp120 bound to native gp41 in immunoreactive form, was free from infectivity in vitro in co-cultures with OCS and in vivo after inoculating SCID-hu Thy/Liv mice. These data should help development of mHIVenv as a virally safe immunogen and enable preparation of polyclonal hyper-immune globulins for immunoprophylaxis against HIV-1 infection.

Pooled peripheral blood mononuclear cells provide an optimized cellular substrate for human immunodeficiency virus Type 1 isolation during acute infection.

BACKGROUND: Cellular substrate (CS) composed of phytohemagglutinin (PHA)-stimulated PBMNCs is required for isolating primary human immunodeficiency virus Type 1 from plasma (PHIV) during early acute infection. The transmitted founder PHIV is neutralization-sensitive and uses chemokine-receptor 5 to infect CD4-positive PBMNCs. Therefore, PHIV cocultured with optimized CS would enable efficient virologic diagnosis, vaccine development, and tests for broadly neutralizing antibodies (bnAb). STUDY DESIGN AND METHODS: Fifteen leukapheresis donations were used to isolate CD4-enriched PBMNCs. Individual or three or four donors' pooled cells were stimulated with PHA, and both CSs were evaluated in parallel cocultures using five different PHIV isolates from nucleic acid testing-positive anti-HIV-negative donations. Feasibility of coculturing PHIV with pooled PBMNC-CS after dimethyl sulfoxide cryopreservation was investigated. RESULTS: The cell-free supernatants from individual CSs contained mean HIV-p24 antigen varying between 20.35 and 85.54 ng/mL, while that from pooled CSs ranged between 57.54 and 88.10 ng/mL. Thus, PBMNCs pooled from multiple donors provide an optimal CS for coculturing PHIV. Cryopreserved PBMNC-CS for PHIV cocultures is promising for systematic biosynthesis of PHIV. CONCLUSIONS: Pooled CSs after cryopreservation were functional for PHIV replication and enable on-demand diagnostic cocultures, preparing panels of PHIV stocks for bnAb testing and developing an envelope-subunit vaccine candidate analogous to hepatitis B surface antigen, proven successful in preventing hepatitis B virus infection.

Variations in Metformin Prescribing for Type 2 Diabetes.

BACKGROUND: Reasons for suboptimal metformin prescribing are unclear, but may be due to perceived risk of lactic acidosis. The purpose of this study is to describe provider attitudes regarding metformin prescribing in various patient situations. METHODS: An anonymous, electronic survey was distributed electronically to 76 health care providers across the nation. The 14-item survey contained demographic questions and questions related to prescribing of metformin for T2DM in various patient situations, including suboptimal glycemic control, alcohol use, history of lactic acidosis, and varying degrees of severity for certain health conditions, including renal and hepatic dysfunction, chronic obstructive pulmonary disease, and heart failure. RESULTS: There were a total of 100 respondents. For suboptimal glycemic control, most providers (75%) would increase metformin from 1500 to 2000 mg daily; however, 25% would add an alternate agent, such as a sulfonylurea (18%) or dipeptidyl peptidase-4 inhibitor (7%). Although 51% of providers would stop metformin based on serum creatinine thresholds, the remainder would rely on glomerular filtration rate thresholds of <60 mL/min (15%), <30 mL/min (33%), or <15 mL/min (1%) to determine when to stop metformin. For heart failure, 45% of providers would continue metformin as currently prescribed regardless of severity. Most providers would adjust metformin for varying severity of hepatic dysfunction (74%) and alcohol abuse (40%). CONCLUSIONS: Despite evidence supporting the cardiovascular benefits of metformin, provider attitudes toward prescribing metformin are suboptimal in certain patient situations and vary greatly by provider.