| 摘要 |
<p>A hog cholera vaccine is prepared by subjecting virulent hog cholera virus to serial culture containing living pig tissue for at least 15 serial passages until said hog cholera virus acquires a reduced virulence that will no longer produce pathological symptoms when injected into a normal pig but retains self-propagating characteristics and gives rise to the production of protective antibodies. Hog serum is ultrafiltered to remove hog cholera immune fractions, diluted with a physiological solution, sterilised, a small quantity of comminuted living reticuloendothelial tissue of a pig susceptible to hog cholera added, the pH adjusted to 7.4 to 7.5 and the medium so formed inoculated with virulent hog cholera virus which is incubated at 37 DEG C. for three days and at room temperature for one day. A cysteine salt, e.g. the hydrochloride and a small amount of pig spleen hydrolysate or p-aminobenzoic acid may also be present in the culture medium. The virus is serially propagated through similar media until the desired attenuation has been obtained. The modified virus is then mixed with an equal volume of a diluent such as sterile skim milk, placed in the final market container and is quick frozen and dried, the containers being stoppered, evacuated and sealed. Specification 627,584 is referred to.</p> |
