GB898783A - Pulpy kidney disease/lamb dysentery/enterotoxaemia vaccine - Google Patents

Abstract

A combined purified vaccine for the protection of sheep and lambs against pulpy kidney disease and dysentery and/or enterotoxaemia comprises an aqueous preparation of toxoided e -toxin from Clostridium welchii, type D, toxoided b -toxin from Cl. welchii, type C and/or toxoided b - and e -toxins from Cl. welchii, type B, containing not less than 30 flocculation equivalents of toxoided e -toxin from Cl. welchii, type D, together with not less than 20 flocculation equivalents of toxoided b -toxin from Cl. welchii, type C and/or not less than 30 flocculation equivalents of toxoided b -toxin from Cl. welchii, type B, not more than 0.05 milligrams of protein nitrogen and not more than 0.5 milligram total nitrogen per millilitre of the preparation. The purified toxoid is prepared by anaerobically culturing a toxigenic strain of the producing organism e.g. Cl. welchii, type D in a culture medium e.g. papain digest of horse meat of pH 8.0 at 37 DEG C. for 18 hours. Separating the bacteria from the medium and converting the toxin and protoxin in the clarified medium to toxoid and protoxoid by treatment with formaldehyde (1% on medium) for 14 to 18 days at 37 DEG C. The protoxoid is then converted to toxoid by treatment with trypsin at 37 DEG C. for 30 to 90 minutes and the total toxoid then precipitated from the medium by the addition of ammonium sulphate. The toxoid is dissolved in water and dialysed to remove residual ammonium sulphate. The purified toxoid is adsorbed on to a parenterally acceptable pharmaceutically carrier such as aluminium hydroxide gel or aluminium phosphate gel. The various purified toxins are adsorbed on to separate carriers before mixing in the desired proportions to produce the potencies required. The vaccine may be buffered at pH 7.0 and contain 0.85% sodium chloride and a preservative.