Abstract: An immunogenicity increasing carrier substance for immunogenic determinants is composed of particles derived from gram-negative cells substantially devoid or depleted of their natural immunogenic determinants, more particularly prepared by stripping the O-antigen and core region off the lipid A by chemical cleavage (acid hydrolysis). These socalled "naked bacteria" are chemically treated with a linking reagent to provide covalently bonded intermediate linking moieties while preserving the adjuvant effect of the particles. The linking moieties have functional groups. These serve for the covalent bonding of selected haptens or antigens comprising the desired immunogenic determinants against which antibodies are to be elicited in living antibody-producing cells.

Abstract: Immunological preparations are prepared by immunizing hens with an immunogen having a molecular or particle weight of at least 30,000, to a stage of hyper-immunization at which there occurs a plateau-like levelling-off of the antibody content of the serum. The immunogenicity of the immunogen can be enhanced by enlarging the immunogen particle mass. The eggs of the immunized hens are collected, the yolk is separated from the eggs, followed by separation of the lipid content of the yolk. The antibodies in the egg yolk are then rendered indispersable with the aid of a water-soluble linear filamentary non-charged polymer precipitant such as PEG and the indispersable antibodies are recovered. This precipitation of antibodies is advantageously preceded by a precipitation of caseinaceous proteins, lipid and yolk particles at lower polymer concentrations. Selected antibodies (IgY or IgG) can be concentrated by pH-controlled fractional precipitation with PEG.

Abstract: The invention provides an immuno-reactant, being either an antigen or an antibody covalently bonded to a cross-linked film, more particularly composed of cross-linked protein or peptides, enveloping a carrier body, e.g. a solid, non-porous glass bead of 6 mm diameter. The immuno-logically active parts of the immuno-reactant are present on the surface in a form in which they are available for immunosorption. If the immuno-reactant is a protein, e.g. an antibody, it can provide all or part of the film-forming material. In a particular embodiment the film carries antibodies against a second type of antibody which is captured immunosorptively to form a "double layer" carrier-bound immunosorbent, the antigen capturing sites of the second type of antibody providing the immunosorption sites of the product. The immunosorbents are used, for example, for RIA or ELISA assays.

Abstract: Immunological preparations are prepared by immunizing hens with an antigen, preferably to a stage of hyperimmunization. The eggs of the immunized hens are collected, the yolk is separated from the eggs, followed by separation of the lipid content of the yolk. The antibodies in the egg yolk are then rendered indispersable with the aid of a water-soluble linear filamentary non-charged polymer precipitant such as PEG and the indispersable antibodies are recovered. This precipitation of antibodies is preferably preceded by a precipitation of caseinaceous proteins at lower polymer concentrations.The immunological preparations are useful for diagnostic purposes and in appropriate cases also for the treatment of pathological conditions.

Abstract: Influenza virus is purified, fractionated or concentrated in an aqueous medium, using a linear filamentary non-charged polymer, preferably polyethylene glycol, as an insolubilising agent, at a concentration not exceeding 5% by weight. Impurities and large virus particles can be fractionated off at PEG concentrations of say up to 1%. Phase separation is achieved most readily when assisted by ultra-centrifugation at low temperature between 0.degree. and 6.degree. C. Precipitation of the virus from dispersions of comparatively high concentration (say 600 HA units or more per ml.) results in intimately aggregated virus particles, which are easier to further purify, and which result in an improved vaccine. Novel concenrates of globular influenza virus are also described.