Abstract: There is disclosed a method for purifying a gene-expression product produced by recombinant DNA technique which comprises a specific sequence of steps including adsorption treatment with silica gel, adsorption treatment with activated carbon, at least twice density gradient centrifugation and at least twice equilibrium density gradient centrifugation. The method of the present invention is very effective to remove allergen from gene-expression products contaminated therewith, enabling highly purified gene-expression products to be produced on a large scale.

Abstract: There is disclosed a method for culturing Bordetella pertussis in the prece of a cellulose and/or cellulose derivatives. The present method is useful for obtaining a mixed antigen comprising pertussis toxin and filamentous hemagglutinin in a large amount at low cost. From the antigen, there can be obtained a stable and effective pertussis toxoid to be used for a pertussis vaccine. There is also disclosed a vaccine comprising the pertussis toxoid as an active ingredient and a gelatin and/or gelatin derivatives as a stabilizing agent. The present vaccine is extremely stable and can be stored for a prolonged period of time.

Abstract: There is disclosed an antigen comprising at least part of an amino acid sence of the antigen of a flavivirus, which part contains at least one of epitopes of the flavivirus antigen. The present antigen can be produced easily and safely at low cost by means of recombinant DNA technique. The present antigen can be used as an effective vaccine and diagnostic for Japanese encephalitis.

Abstract: A distributed feedback semiconductor laser in which the waveguide on one side of the active layer consists of two layers forming a corrugation pattern therebetween to create a Bragg grating. The refractive index of the inner layer, with respect to the active layer is less than that of the outer layer and the refractive index of the outer layer is less than that of the active layer.

Abstract: An expression vector carrying a gene coding for a phosphate-binding protein has been found to have a strong gene expression. The expression vector can be produced by transforming a bacterium belonging to Enterobacteriaceae with a recombinant vector carrying a DNA fragment containing a gene coding for a phosphate-binding protein to form transformants, selecting the transformants containing the desired recombinant vector from said transformants, and isolating the desired recombinant vector from the selected transformants. The expression vector is useful for producing polypeptides.

Abstract: A live attenuated mumps virus vaccine is prepared by cultivating a wild mumps virus strain for 1-18 serial passages in a first living cell to attenuate the virus, and then cultivating the attenuated virus in a second living cell for at least one serial passage to propagate and adapt the virus to the cell. The cell is selected from embryonated hen's egg amnion, embryonated hen's egg chorio-allantoic membrane, chick embryo fibroblast and human diploid cell. Quail embryo fibroblast is also employed. The vaccine prepared has strong immunogenecity and is safe.

Abstract: Process for preparing a virus disease live vaccine by employing culture of a quail embryonated egg or tissue culture of a quail embryo fibroblast for cultivation of the virus. The vaccine obtained according to the present invention is effective for immunization of animals and humans against the virus disease. The vaccine is avirulent, scarcely subject to induction of unfavorable factors accompanying the present tissue used for isolation of the virus therefrom, and economically productible.

Abstract: A process for the attenuation of varicella virus comprising passaging varicella virus in a guinea pig primary embryonic tissue cell. Live avirulent varicella vaccines are also advantageously prepared by continuing the passaging until the virus is sufficiently attenuated for use as a live avirulent varicella vaccine.