Other

George H Yoakum

Curtis C Harris

Brent E Korba

John F Lechner

A process for production of improved polyethylene glycol (PEG) is disclosed. This process overcomes the toxicity that results from using the known (and impure) PEG-fusion reagent by incorporation of a purification method that removes the toxic elements always present in PEG preparations stored above 0.degree. C. in the presence of oxygen.

Polyethylene glycol (PEG) reagent

A modified protoplast fusion method and cell line is disclosed that stably transfects human cells with pSV2-derived plasmids at frequencies greater than 10.sup.-3. This procedure makes it possible to test the biological effect of individual genes (i.e., oncogenes and other cellular genes, and viral genes). To demonstrate the utility of this invention, a pSV2gpt.sup.+ plasmid constructed to carry a subgenomic fragment of hepatitis B virus (HBV) that contained the core antigen gene (HBc gene) is transfected into human cells. Human cell lines are stably transfected with the HBC.sup.+ gene by selecting recipient cells for expression of guanine phosphoribosyl transferase expression; other selective markers, i.e., neomycin resistance, can also be used. Conditions for enhancing the expression of the transfected gene(s) have also been developed. For example, with this gpt.sup.+ /HBc.sup.+ cell line it is shown that growth in serum-free medium or treatment with 5'-azacytidine stimulates the production of the HBV core antigen.

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Gaithersburg, MD, United States of America

George H Yoakum