Secreted expression of human lysozyme in the yeast Pichia pastoris under the direction of the signal peptide from human serum albumin.

hLM (human lysozyme) has important potential application as a future safely administered human drug and food additive. To produce secreted rhLM (recombinant hLM) from the yeast Pichia pastoris, the signal peptide from HSA (human serum albumin) was employed to direct secreted expression. On the basis of the vector pPIC3.5k, an overexpression vector, pPIC3.5k-hLM, carrying the strong promoter AOX1 (aldehyde oxidase 1), the HSA signal peptide, the enterokinase recognition motif, the lysozyme gene and other necessary genetic segments was constructed and this was followed by a series of genetic manipulations. A positive colony was picked off to test its expression pattern. The target protein, rhLM, was obtained from the supernatant and showed a gradual enrichment with the induction time course, reaching its highest level at 72 h. This pattern was identical with that shown by the secreted expression of a heterologous protein directed by Saccharomcyes cerevisiae a-mating factor prepro-signal peptide in P. pastoris. After a series of purification processes, including ultrafiltration with a hollow-fibre membrane module, DEAE-Sepharose, Sephadex G50 chromatography and enterokinase digestion, the mature protein was characterized by MALDI-TOF-MS/MS (matrix-assisted laser-desorption ionization-time-of-flight tandem MS), N-terminal amino acid sequencing, and K(m) and K(cat) determination. The results confirmed that the rhLM was identical with native hLM. Moreover, the mature protein exhibited in vitro bacteriolytic activity against the Gram-positive bacterium Micrococcus lysodeikticus and the Gram-negative bacterium Escherichia coli. Taken together, it appeared that the HSA signal peptide was able direct secretive expression of a heterologous protein in P. pastoris.

Author Correction: HIV-1 Transmissions Among Recently Infected Individuals in Southwest China are Predominantly Derived from Circulating Local Strains.

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HIV-1 Transmissions Among Recently Infected Individuals in Southwest China are Predominantly Derived from Circulating Local Strains.

Although the Guangxi region accounts for 10% of all HIV-1 cases new reported in 2011 in China, the sources of the transmitted HIV-1 strains are virtually unknown. To determine the extent to which recent HIV infections were derived from already circulating local strains as opposed to recently introduced strains, we performed a cross-sectional molecular epidemiological investigation of recent infections across Guangxi during 2012-2013. HIV-1 nucleotide sequences were amplified and sequenced. Phylogenetic analyses of pol gene regions were used to determine HIV-1 transmission source strains. Based on 229 sequences generated, the subtype/CRF distribution was as follows: CRF01_AE (61.1%), CRF07_BC (18.8%), CRF08_BC (16.6%), CRF55_01B (3.1%), and subtype B' (0.4%). In total, 213 of 229 (93.0%) sequenced transmission strains were derived from already-circulating local strains. Multivariate logistic regression analysis showed that only an age of 18-25 years was significantly associated with transmission from outside Guangxi (compared to >25 years, AOR: 5.15, 95% CI: 1.18-22.48, p < 0.01). This is the first study to use a Bayesian discrete phylogeographic approach to analyze transmission source strains in China. Our results provide useful data for designing evidence-based prevention strategies and methods for combating the rapid spread of sexually transmitted HIV in Guangxi.

Near Full-Length Genomic Characterization of a Novel HIV Type 1 CRF01_AE/CRF07_BC Recombinant Form Transmitted Between a Heterosexual Couple in Guangxi, China.

In this research, we reported a new second generation recombinant form (GXDY460B) between circulating recombinant form (CRF)01_AE and CRF07_BC in a seroconversion couple who obtained the virus from her husband by heterosexual behavior. The analysis result of the near full-length genomic characterization showed that the genome comprises at least 12 interlaced segments, including six CRF07_BC and six CRF01_AE segments, with CRF07_BC as the main framework. Cocirculation of multiple virus subtypes and multiple infection routes have existed for a long time in Guangxi, but the recombinant strain was rarely reported among heterosexual transmission population because of its lower crowd confounding degree than men who have sex with men and injecting drug user population. It is the first time that the unique recombinant form (URF) between CRF01_AE and CRF07_BC was identified among heterosexual transmission in Guangxi. The emergence of the novel recombinant helps to understand the pattern of the URF virus.

[Efficacy of antiviral therapy on prevention of HIV transmission among sero-discordant couples in Guangxi Zhuang autonomous region].

OBJECTIVE: To understand the efficacy of antiviral therapy on prevention of HIV transmission and to assess the feasibility of treatment-as-prevention strategy in public health practice, among sero-discordant couples in Guangxi Zhuang autonomous region (Guangxi). METHODS: Data was gathered through the AIDS prevention and control information system in Guangxi from January 1, 2008 to December 31, 2014, on HIV sero-discordant couples. Time-dependent Cox Model was used to analyze the efficacy of antiviral treatment. RESULTS: A total of 7 694 sero-discordant couples were followed and 394 appeared positive from those negative spouses. The overall HIV positive seroconversion rate was 2.5 (2.2-2.7) /100 person-year. The HIV positive sero-conversion rates were 4.3 (3.7-4.8) /100 person-year in the untreated cohort and 1.6 (1.4-1.9) per 100 person-year in the treated cohort. Rate of HIV transmission declined by 51% in the treated cohort (HR=0.49, 95%CI: 0.40-0.60) but appeared as 45% (AHR=0.55, 95%CI:0.43-0.69) after adjusting for factors as sex, age, education, marital status, occupation, transmission route and baseline CD4(+)T lymphocyte cell count. The rate of reduction in transmission was significant among couples in which the HIV-positive spouses showing the following features as: aged ≥25 years, married, farmers, with educational level of junior high school or below, baseline CD4(+)T lymphocyte cell count <500 cells/mm(3) and infection was through heterosexual intercourse. CONCLUSION: Antiviral therapy as a prevention strategy among sero-discordant couples seemed feasible and effective in Guangxi. Expansion of the coverage on antiviral therapy would reduce the spread of HIV in married couples.

Near full-length genome characterization of a new CRF01_AE/CRF08_BC recombinant transmitted between a heterosexual couple in Guangxi, China.

Human immunodeficiency virus type 1 (HIV-1) subtype CRF01_AE is transmitted mainly by sexual activity in Guangxi, southwestern China. Other subtypes, including CRF07_BC, CRF08_BC, and subtype B, are also prevalent in this region. Cocirculation of multiple subtypes, as well as a high rate of drug use, creates favorable conditions for the emergence of recombinant viruses in Guangxi. In the present study, we identified a new HIV-1 unique recombinant form (CRF01_AE /08BC) transmitted from the infected index patient to his seronegative sexual partner. This is the first near full-length genome characterization of a CRF01_AE /08BC recombinant virus in Guangxi, and provides an important basis for future analysis on potential new recombinant transmission events.

Highly potent silver-organoalkoxysilane antimicrobial porous nanomembrane.

We used a simple electrospinning technique to fabricate a highly potent silver-organoalkoxysilane antimicrobial composite from AgNO3-polyvinylpyrrolidone (PVP)/3-aminopropyltrimethoxysilane (APTMS)/tetraethoxysilane (TEOS) solution. Spectroscopic and microscopic analyses of the composite showed that the fibers contain an organoalkoxysilane 'skeleton,' 0.18 molecules/nm2 surface amino groups, and highly dispersed and uniformly distributed silver nanoparticles (5 nm in size). Incorporation of organoalkoxysilanes is highly beneficial to the antimicrobial mat as (1) amino groups of APTMS are adhesive and biocidal to microorganisms, (2) polycondensation of APTMS and TEOS increases the membrane's surface area by forming silicon bonds that stabilize fibers and form a composite mat with membranous structure and high porosity, and (3) the organoalkoxysilanes are also instrumental to the synthesis of the very small-sized and highly dispersed silver metal particles in the fiber mat. Antimicrobial property of the composite was evaluated by disk diffusion, minimum inhibition concentration (MIC), kinetic, and extended use assays on bacteria (Escherichia coli, Bacillus anthracis, Staphylococcus aureus, and Brucella suis), a fungus (Aspergillus niger), and the Newcastle disease virus. The membrane shows quick and sustained broad-spectrum antimicrobial activity. Only 0.3 mg of fibers is required to achieve MIC against all the test organisms. Bacteria are inhibited within 30 min of contact, and the fibers can be used repeatedly. The composite is silver efficient and environment friendly, and its membranous structure is suitable for many practical applications as in air filters, antimicrobial linen, coatings, bioadhesives, and biofilms.

New strategy for expression of recombinant hydroxylated human-derived gelatin in Pichia pastoris KM71.

Gelatin is a well-known biopolymer, and it has a long history of use mainly as a gelling agent in the food industry. This paper reports a new method for producing recombinant hydroxylated human-derived gelatin in Pichia pastoris KM71. Three independent expression cassettes encoding for specific length of gelatin, prolyl 4-hydroxylase (P4H, EC 1.14.11.2), α-subunit (αP4H), and protein-disulfide isomerase (PDI) were individually cloned in one expression vector, pPIC9K. The modified gelatin gene and two subunit genes of P4H were under the control of two different inducible promoters, namely, alcohol oxidase 1 promoter (PAOX1) and formaldehyde dehydrogenase 1 promoter (PFLD1), respectively. The results of sodium dodecylsulfate-polyacrylamide gel electrophoresis show that a recombinant gelatin was successfully expressed in P. pastoris KM71 by methanol induction. Liquid chromatography coupled with tandem mass spectrometry analysis indicates that the expressed gelatin was hydroxylated with approximately 66.7% of proline residues in the Y positions of Gly-X-Y triplets. The results of nuclear magnetic resonance spectroscopy of recombinant gelatin test show that the (1)H and (13)C spectra have many corresponding characteristic displacement peaks, and amino acids composition analysis shows that it contains hydroxyproline and its UV absorption is consistent with the characteristics of gelatin.

Process for coproduction of crude immunoglobulin y and high-density lipoproteins from hen egg yolk.

High value-added products from hen egg are receiving increasing attention from both egg academic and industrial circles due to their potential applications in research and medicine as well as the benefits they bring to egg-breaking industries. This paper reports a simple method for the preparation of immunoglobulin Y (IgY) and high-density lipoproteins (HDL) from hen egg yolk. A water dilution method coupled with (NH4)2SO4 precipitation was employed to prepare the two target proteins. SDS-PAGE under reducing or nonreducing conditions and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) were used to characterize the two products. Western blotting and histobiochemical staining were utilized to qualitatively analyze IgY and HDL, respectively. The purities of prepared IgY and HDL were detected by ELISA and a direct high-density lipoprotein-cholesterol assay, respectively. Results show that dilution times 15 makes IgY and HDL separate well from each other. Western blotting proves IgY has an immunocompetence similar to that of human IgG. Histobiochemical staining shows HDL is composed of sugar, lipid, and protein. The quantitative evaluation of the products indicates that approximately 3 kg of IgY and 2 kg of HDL with purities of 72.7 and 71.9%, respectively, are available from 1 ton of shell eggs via this process.