41. He studied cowpox vaccine from Bernard Jean Bettelheim, the first Christian missionary to Ryukyu, in 1846. 42. He had done a long-term experiment, and began to give cowpox vaccine two years later. 43. Although Jenner had used cowpox virus, a third virus, vaccinia, became the standard vaccine against smallpox. 44. Some experienced mild fevers and armpit soreness _ a signal that their lymph glands were fighting the localized cowpox . 45. He is studying the pill in mice infected with the cowpox virus, which is closely related to smallpox. 46. Some viruses express caspase inhibitors that inhibit caspase activity and an example is the CrmA protein of cowpox viruses. 47. The cowpox virus contains 186 thousand base pairs of DNA, which contains the information for about 187 genes. 48. Jesty and two of his female servants, Ann Notley and Mary Reade, had been infected with cowpox . 49. Experts say vaccinia is related to the smallpox and cowpox viruses, but its origin is a major scientific mystery. 50. Knowledge of the ability of cowpox to provide immunity from smallpox was present in England before Jenner's discovery.
