A method of preparing a vaccine against trachoma.

摘要

A vaccine for protection of humans against trachoma comprises purified virulent or attenuated living trachoma virus or inclusion blennorrhoea virus and an injectable pharmaceutical carrier or diluent. The attenuated virus is obtained by many passages through a host such as thick embryos, tissue cultures and animal hosts. It is preferred to cultivate the virulent or attenuated virus in thick embryos which are 6 to 8 days old at inoculation. The embryos are inoculated via the yolk sac with a suspension in saline of yolk sac infected with the virus and containing streptomycin to prevent bacterial infection and are incubated at 35 DEG C. until the yolk sac is rich in virus, any eggs dying within 72 hours of inoculation being rejected. Infected yolk sacs free from bacteria are homogenized with phosphate buffered saline and centrifuged at 200 G for 5 minutes to remove impurities. The supernatant is mixed with more phosphate buffered saline and centrifuged at 40 DEG C. and 12,000 G to deposit the virus. The process is repeated on the deposited virus to bring about further purification. The virus is resuspended in phosphate buffered saline and mixed with sterile aqueous gelatine to give a final concentration of 10% aqueous gelatine. When required for use, the freeze dried product is reconstituted with sterile pyrogen free water. The gelatin is used to inhibit denaturation of the virus during freeze drying and may be replaced by dextran. Specification 764,718 is referred to.