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Biomedical subjects

S Y Gu

Publications and source records attributed to S Y Gu.

10 recordsLinked to original sources
PubMed1995

First EBV vaccine trial in humans using recombinant vaccinia virus expressing the major membrane antigen.

In the absence of a truly representative animal model, the question of whether EBV-related diseases can be prevented by a vaccine has been studied for the first time in humans. A live recombinant virus based on the licensed vaccinia strain Tien Tan, expressing under the 11K vaccinia promoter the major EBV membrane antigen BNLF-1 MA (gp 220-340), was constructed and tested in three different human populations: EBV-positive and vaccinia-virus-exposed adults; EBV-positive, non-vaccinia-virus-exposed juveniles; and EBV and vaccinia virus-naive infants. No significant titre variations for EBV were observed in the adults, but EBV-neutralising titres increased in the vaccinated juveniles, while antibodies to VCA of EBV remained unchanged. All nine vaccinated infants developed antibodies to MA (membrane antigen) with neutralising properties in vitro; three of these infants were infected by EBV via natural routes over a period of 16 months after vaccination and all ten unvaccinated control infants became infected. It has been shown for the first time that protection against and/or delay of EBV infection by the natural route is possible in humans and that live vaccinia vectors can be used and are efficacious.

Adult↗
PubMed1994

The Epstein-Barr virus-encoded glycoprotein gp 110 (BALF 4) can serve as a target for antibody-dependent cell-mediated cytotoxicity (ADCC).

Antibody-dependent cell-mediated cytotoxicity (ADCC) is thought to play a major role in controlling the spread of the Epstein-Barr virus (EBV) in an infected individual. Recently, the viral membrane protein gp 350/220, which is also expressed at the surface of the virus producing cell, was identified as a target for ADCC reactions. Due to its glycoprotein nature, the EBV protein gp 110 is another possible ADCC target. It is one of the most abundant proteins found during the late phase of viral replication; until now, however, researchers have not been able to localize it on the surface of EBV positive cells. By means of recombinant vaccinia viruses containing the genes for gp 350/220 and gp 110, respectively, we expressed these proteins in lymphoblastoid cells, which were then used as targets in ADCC studies with sera from EBV-positive and -negative individuals. In these experiments we were able to demonstrate the feasibility of our approach for the investigation of EBV-specific ADCC reactions and could confirm the role of gp 350/220 as an ADCC target. Furthermore, we were able to show that gp 110 can also be recognized in an ADCC reaction, proving that at least some gp 110 molecules must be expressed at the cell surface.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1986

Sandwich nucleic acid hybridization: a method with a universally usable labeled probe for various specific tests.

Nucleic acid hybridization is widely used for scientific applications but essentially restricted to specialized laboratories. The use of recombinant m 13 phages as hybridization probes (Hu and Messing (1980) Gene 17, 271; Messing (1983) Methods Enzymol. 101, 20) offers a considerable advantage over the commonly used recombinant plasmids as the preparation of the DNA probe is very simple and it can easily be labeled directly, e.g. with isotopes with long half-life like 125I (Commerford (1971) Biochemistry 10, 11 (1983); Gu et al. (1983) Cancer (China) 2, 129; Han and Harding (1983) Nucleic Acids Res. 11, 14) and used for hybridization. However, as the application of nucleic acid hybridization for diagnostic and epidemiological purposes becomes almost unavoidable, the logistic problems of keeping numerous individually labeled hybridization probes increase considerably and may reach prohibitory levels in less well-equipped laboratories. In a new sandwich technique, the first step involves hybridization with an unlabeled recombinant m 13 DNA carrying an insert of the desired specificity. In a second step a universally usable labeled probe directed against the m 13 part of the recombinant phage DNA is applied. This reduces considerably the problems of preparing and keeping multiple labeled probes in stock.

Bacteriophages↗
PubMed1986

[Labelling of DNA by iodination and its application on the detection of EBV-DNA].

The authors developed a simple and efficient method--the iodination of the single-stranded DNA catalyzed by thallium chloride in vitro. The 125I-labelled DNA has a specific activity higher than 10(8) cpm/micrograms DNA. This reaction does not involve any enzyme. The optimal conditions of the iodinating reaction, including the high temperature, low pH and the concentrations of DNA and iodine, are described. 125I-labelled DNA inserted with the fragment of EBV-DNA are used to detect EBV-DNA by blot and spot and in situ hybridization.

DNA, Single-Stranded↗
PubMed1984

New developments in nucleic acid hybridization.

Nucleic acid hybridization is widely used for scientific applications in specialized laboratories. This paper describes hybridization probes that can be prepared with less specialized equipment. A new indirect 'sandwich' hybridization test is described which allows the use of only one universally usable labelled probe for hybridization tests with specificities for various sequences. The use of different labels and hybridization techniques is also discussed and critically compared. For in situ hybridization, the usability of fixed and embedded materials is tested and evaluated.

DNA, Viral↗
PubMed1984

Strategies for the economic preparation of Epstein-Barr virus proteins of diagnostic and protective value by genetic engineering: a new approach based on segments of virus-encoded gene products.

Immunoprecipitation of Epstein-Barr viral proteins with various sera from normal adults, patients with fresh infectious mononucleosis or nasopharyngeal carcinoma was used to identify antigens which are of importance in the determination of immune status and characteristic of a particular disease. Some genes coding for of these antigens have been localized on the Epstein-Barr virus (EBV) genome by hybrid-selected translation. With the use of sequence data, these genes could then be subcloned from EBV DNA and expressed in eukaryotic and prokaryotic cells. Data on the expression are presented and the application of the methods described for the production of diagnostic reagents and vaccines is discussed.

Antibodies, Viral↗