19th century serology

Harvard Medical School associate professor of Global Health and Social Medicine Dr. Scott Podolsky writes in Annals of Internal Medicine that ZMapp is inspired by serology techniques developed in the 1890s after Louis Pasteur and Robert Koch began to identify the agents of diseases like anthrax, diptheria and pneumonia:

From the 1890s onward, this model of production – expose an animal (guinea pig, rabbit, cow, horse, etc.) to an identified microbial pathogen, generate antibodies (or use convalescent serum from former patients), and then ‘passively’ transfer the pre-formed antibodies to an exposed animal or person – could be expanded to such feared and prevalent diseases as pneumococcal pneumonia and meningococcal meningitis.