The V1-V3 region of a brain-derived HIV-1 envelope glycoprotein determines macrophage tropism,low CD4 dependence,increased fusogenicity and altered sensitivity to entry inhibitors

Background

HIV-1 infects macrophages and microglia in the brain and can cause neurological disorders in infected patients. We and others have shown that brain-derived envelope glycoproteins (Env) have lower CD4 dependence and higher avidity for CD4 than those from peripheral isolates, and we have also observed increased fusogenicity and reduced sensitivity to the fusion inhibitor T-1249. Due to the genetic differences between brain and spleen env from one individual throughout gp120 and in gp41's heptad repeat 2 (HR2), we investigated the viral determinants for the phenotypic differences by performing functional studies with chimeric and mutant Env.

Results

Chimeric Env showed that the V1/V2-C2-V3 region in brain's gp120 determines the low CD4 dependence and high avidity for CD4, as well as macrophage tropism and reduced sensitivity to the small molecule BMS-378806. Changes in brain gp41's HR2 region did not contribute to the increased fusogenicity or to the reduced sensitivity to T-1249, since a T-1249-based peptide containing residues found in brain's but not in spleen's HR2 had similar potency than T-1249 and interacted similarly with an immobilized heptad repeat 1-derived peptide in surface plasmon resonance analysis. However, the increased fusogenicity and reduced T-1249 sensitivity of brain and certain chimeric Env mostly correlated with the low CD4 dependence and high avidity for CD4 determined by brain's V1-V3 region. Remarkably, most but not all of these low CD4-dependent, macrophage tropic envelopes glycoproteins also had increased sensitivity to the novel allosteric entry inhibitor HNG-105. The gp120's C2 region asparagine 283 (N283) has been previously associated with macrophage tropism, brain infection, lower CD4 dependence and higher CD4 affinity. Therefore, we introduced the N283T mutation into an env clone from a brain-derived isolate and into a brain tissue-derived env clone, and the T283N change into a spleen-derived env from the same individual; however, we found that their phenotypes were not affected.

Conclusion

We have identified that the V1-V3 region of a brain-derived envelope glycoprotein seems to play a crucial role in determining not only the low CD4 dependence and increased macrophage tropism, but also the augmented fusogenicity and reduced sensitivity to T-1249 and BMS-378806. By contrast, increased sensitivity to HNG-105 mostly correlated with low CD4 dependence and macrophage tropism but was not determined by the presence of the brain's V1-V3 region, confirming that viral determinants of phenotypic changes in brain-derived envelope glycoproteins are likely complex and context-dependent.

     

Determination of zinc, copper, lead and cadmium in some medicinally important leaves by differential pulse anodic stripping analysis

Levels of zinc, copper, lead and cadmium have been determined in some medicinally important leaves by differential pulse anodic stripping voltammetry (DPASV). High pressure digestion with nitric acid (HPA) was used for sample digestion. The accuracy of the method was verified by the parallel analysis of leaves with inductively coupled plasma atomic emission spectroscopy (ICP-AES) and recovery studies by the analysis of standard reference materials. Based on elemental levels the utility of these leaves in medicine are discussed. Statistical treatment has been used in order to understand the correlation between elements in these leaves.     

应用附加绿黄色光二极管的黄色胶片监测温室中的粉虱、蚜虫和蕈蚊

绿黄色光二极管(LED)附加在塑胶杯和胶片捕捉器可增加捕捉实验室和温室中昆虫的数量。附加有530nm绿黄色LED的塑胶杯捕捉器比没有附加的捕捉到更多的Trialeurodes vaporariorum(Westwood)和Bemisia tabaci(Gennadius)B生态型。在温室中昆虫笼以四季豆和棉花试验,附加有530nm绿黄色LED的黄色胶片(YC)和透明塑胶片(CS)分别缩写为LED—YC和LED—CS)比每一种没有附加的捕捉器捕捉到更多的T.vaporariorum,B．tabaci B生态型,Ahis gossypii(Glover)和Bradysia coprophila(Lintner)成虫。绿黄色LED—YC在温室中有用为监测和控制的潜在性。     

Development of recombinant single-chain variable fragment against hepatitis A virus and its use in quantification of hepatitis A antigen

Phage display technology has been utilized for identification of specific binding molecules to an antigenic target thereby enabling the rapid generation and selection of high affinity, fully human antibodies directed towards disease target appropriate for antibody therapy. In the present study, single chain Fv antibody fragment (scFv) to hepatitis A virus (HAV) was selected from phage displayed antibody library constructed from peripheral blood lymphocytes (PBLs) of a vaccinated donor. The variable heavy (V(H)) and light chains (V(L)) were amplified using cDNA as template, assembled into scFv using splicing by overlap extension PCR (SOE PCR) and cloned into phagemid vector as a fusion for display of scFv on bacteriophage. The phage displaying antibody fragments were subjected to three rounds of panning with HAV antigen on solid phase. High affinity antibodies reactive to hepatitis A virus were identified by phage ELISA and cloned into a bacterial expression vector pET20b. The scFv was purified by immobilized metal affinity chromatography (IMAC) on a nickel-nitrilotriacetic acid (NTA) agarose column and characterized. The binding activity and specificity of the scFv was established by its non-reactivity towards other human viral antigens as determined by ELISA and immunoblot analysis. The scFv was further used in the development of an in-house IC-ELISA format in combination with a commercially available mouse monoclonal antibody for the quantification of hepatitis A virus antigen in human vaccine preparations. The adjusted r2 values obtained by subjecting the values obtained by quantification of the NIBSC standards using the commercial and the in-house ELISA kits by regression analysis were 0.99 and 0.95. 39 vaccine samples were subjected to quantification using both the kits. Regressional statistical analysis through the origin of the samples indicated International Unit (IU) values of 0.0416x and 0.0419x, respectively for the commercial and in-house kit respectively.     

Studying the Logone floodplain,Cameroon, as a coupled human and natural system§

African floodplains are an excellent example of coupled human–natural systems because they exhibit strong interactions among multiple social, ecological, and hydrological systems. The intra-annual and interannual variations in seasonal flooding have direct and indirect impacts on ecosystems and human lives and livelihoods. Coupled human and natural system (CHANS) is a broad conceptual framework that is used to study systems in which human and natural components interact. While there are other conceptual frameworks to study social-ecological systems, the CHANS framework offers a clear way of studying the interactions, called couplings, between human and natural systems. Core features of the framework are the following: human and natural systems are analytically separated; focus is on processes within and couplings between systems; and the goal is to build an integrative, quantitative model of the coupled system. This paper explains the conceptual framework of coupled systems, using the case study of the Logone floodplain in Cameroon. We compare the CHANS framework with other frameworks that have been used to study the same floodplain, and argue for its usefulness in the study of African floodplains.