Two novel fusion inhibitors of human respiratory syncytial virus

To search for novel drugs against human respiratory syncytial virus (RSV), we have screened a diversity collection of 16,671 compounds for anti-RSV activity in cultures of HEp-2 cells. Two of the hit compounds, i.e., the N-(2-hydroxyethyl)-4-methoxy-N-methyl-3-(6-methyl[1,2,4]triazolo[3,4-a]phthalazin-3-yl)benzenesulfonamide (designated as P13) and the 1,4-bis(3-methyl-4-pyridinyl)-1,4-diazepane (designated as C15), reduced the virus infectivity with IC₅₀ values of 0.11 and 0.13 μM respectively. The concentration of P13 and C15 that reduced the viability of HEp-2 cells by 50% was 310 and 75 μM respectively. Both P13 and C15 exhibited no direct virucidal activity or inhibitory effects on the virus attachment to cells. However, to inhibit formation of RSV-induced syncytial plaques P13 and C15 had to be present during the virus entry into the cells and the cell-to-cell transmission of the virus. The RSV multiplication in HEp-2 cells in the presence of P13 or C15 resulted in rapid selection of viral variants that were ∼1000 times less sensitive to these drugs than original virus. Sequencing of resistant viruses revealed presence of amino acid substitutions in the F protein of RSV, i.e., the D489G for C15-selected, and the T400I and N197T (some clones) for the P13-selected virus variants. In conclusion, we have identified two novel fusion inhibitors of RSV, and the detailed understanding of their mode of antiviral activity including selection for the drug resistant viral variants may help to develop selective and efficient anti-RSV drugs.     

A comprehensive review of the phenotype and function of antigen-specific immunoregulatory double negative T cells

Double negative T cells that lack the expression of both CD4 and CD8 T cell co-receptors exhibit a most unique antigen-specific immunoregulatory potential first described over a decade ago. Due to their immunoregulatory function, this rare T cell population has been studied in both mice and humans for their contribution to peripheral tolerance and disease prevention. Consequently, double negative cells are gaining interest as a potential cellular therapeutic. Herein, we review the phenotype and function of double negative T cells with emphasis on their capacity to induce antigen-specific immune tolerance. While the phenotypic and functional similarities between double negative T cells identified in mouse and humans are highlighted, we also call attention to the need for a specific marker of double negative T cells, which will facilitate future studies in humans. Altogether, due to their unique properties, double negative T cells present a promising therapeutic potential in the context of various disease settings.     

HIV-1 superinfection can occur in the presence of broadly neutralizing antibodies

BackgroundSuperinfection of individuals already infected with HIV-1 suggests that pre-existing immune responses may not adequately protect against re-infection. We assessed high-risk female sex workers initially infected with HIV-1 clades A, D or A/D recombinants, to determine if HIV-1 broadly neutralizing antibodies were lacking prior to superinfection.MethodsSix superinfected female sex workers previously stratified by HIV-1 high-risk behavior, infecting virus clade and volunteer CD4 counts were evaluated at baseline (n = 5) and at 350 days post-superinfection (n = 6); one superinfected volunteer lacked pre-superinfection plasma. Retrospective plasmas were assessed for neutralization of a multi-clade panel of 12 HIV-1 viruses before superinfection, and then at quarterly intervals thereafter. Similarly stratified singly infected female sex workers were correspondingly assessed at baseline (n = 19) and 350 days after superinfection (n = 24). Neutralization of at least 50% of the 12 viruses (broad neutralization), and geometric means of the neutralization titers (IC₅₀) were compared before and after superinfection; and were correlated with the volunteer HIV-1 superinfection status, CD4 counts, and pseudovirus clade.ResultsPreexisting broad neutralization occurred in 80% (4/5) of the superinfected subjects with no further broadening by 350 days after superinfection. In one of the five subjects, HIV-1 superinfection occurred when broad neutralization was lacking; with subsequent broadening of neutralizing antibodies occuring within 9 months and plateauing by 30 months after detection of superinfection. Clade B and C pseudoviruses were more sensitive to neutralization (13; [87%]); and (12; [80%]) than the locally circulating clades A (10; [67%]) and D (6; [40%]), respectively (p = 0.025). Low antibody titers correlated with clade D viruses and with >500 CD4 T cell counts, but not with the superinfection status.ConclusionThese data demonstrate that HIV-1 superinfection can occur both in the presence, and in the absence of broadly neutralizing antibodies.     

Transient heating of expressed breast milk up to 65°C inactivates HIV‐1 in milk: A simple,rapid, and cost‐effective method to prevent postnatal transmission

The postnatal transmission of human immunodeficiency virus (HIV) from mothers to children occurs through breastfeeding. Although heat treatment of expressed breast milk is a promising approach to make breastfeeding safer, it is still not popular, mainly because the recommended procedures are difficult to follow, or time‐consuming, or because mothers do not know which temperature is sufficient to inactivate HIV without destroying the nutritional elements of milk. To overcome these drawbacks, a simple and rapid method of heat treatment that a mother could perform with regular household materials applying her day‐to‐day art of cooking was examined. This structured experiment has demonstrated that both cell‐free and cell‐associated HIV type 1 (HIV‐1) in expressed breast milk could be inactivated once the temperature of milk reached 65°C. Furthermore, a heating method as simple as heating the milk in a pan over a stove to 65°C inhibited HIV‐1 transmission retaining milk's nutritional key elements, for example, total protein, IgG, IgA, and vitamin B₁₂. This study has highlighted a simple, handy, and cost‐effective method of heat treatment of expressed breast milk that mothers infected with HIV could apply easily and with more confidence. J. Med. Virol. 85:187–193, 2013. © 2012 Wiley Periodicals, Inc.     

中国人共刺激信号抑制配体表达载体的构建及在大肠杆菌DH5α中的表达

构建CTLA－4基因表达载体并在大肠杆菌DH5α中表达CTLA－4蛋白。方法：用PCR方法获得中国人CTLA－4基因第二外显子，构建重组表达质粒pPBCTLA，转化大肠杆菌DH5α，以PCR和RFLP方法筛选阳性克隆，以免疫印迹技术检测表达产物。结果：阳性重组子在DH5α中经温度诱导表达CTLA－4蛋白，分子量与理论值相符（约12kD)，进一步分析表明，CTLA－4蛋白主要以包涵体形式存在。Western-blot结果证实，12k的表达条带可与标准羊抗人CTLA－4ITgG起特异反应。淋巴细胞转化实验结果表明该蛋白具有明显的免疫抑制作用。结论：用基因工程技术获得中国人CTLA－4基因表达蛋白，为进一步研究CTLA－4的生物学功能及研制CTLA－4抗体奠定了基础。