brodie came up with the vaccine for polio.
brodie came up with the vaccine for polio.
who came up with the vaccine for polio?
brodie
during the early 1950s, polio rates in the u.s. were above 25,000 annually; in 1952 and 1953, the u.s. experienced an outbreak of 58,000 and 35,000 polio cases, respectively, up from a typical number of some 20,000 a year, with deaths in those years numbering 3,200 and 1,400. amid this u.s. polio epidemic, millions of dollars were invested in finding and marketing a polio vaccine by commercial interests, including lederle laboratories in new york under the direction of h. r. cox. also working at lederle was polish-born virologist and immunologist hilary koprowski of the wistar institute in philadelphia, who tested the first successful polio vaccine, in 1950. his vaccine, however, being a live attenuated virus taken orally, was still in the research stage and would not be ready for use until five years after jonas salk's polio vaccine (a dead-virus injectable vaccine) had reached the market. koprowski's attenuated vaccine was prepared by successive passages through the brains of swiss albino mice. by the seventh passage, the vaccine strains could no longer infect nervous tissue or cause paralysis. after one to three further passages on rats, the vaccine was deemed safe for human use. on 27 february 1950, koprowski's live, attenuated vaccine was tested for the first time on an 8-year-old boy living at letchworth village, an institution for the physically and mentally disabled located in new york. after the child suffered no side effects, koprowski enlarged his experiment to include 19 other children.
polio vaccine
opv is an attenuated vaccine, produced by the passage of the virus through nonhuman cells at a subphysiological temperature, which produces spontaneous mutations in the viral genome. oral polio vaccines were developed by several groups, one of which was led by albert sabin. other groups, led by hilary koprowski and h.r. cox, developed their own attenuated vaccine strains. in 1958, the national institutes of health created a special committee on live polio vaccines. the various vaccines were carefully evaluated for their ability to induce immunity to polio, while retaining a low incidence of neuropathogenicity in monkeys. large-scale clinical trials performed in the soviet union in late 1950s to early 1960s by mikhail chumakov and his colleagues demonstrated safety and high efficacy of the vaccine. based on these results, the sabin strains were chosen for worldwide distribution. fifty-seven nucleotide substitutions distinguish the attenuated sabin 1 strain from its virulent parent (the mahoney serotype), two nucleotide substitutions attenuate the sabin 2 strain, and 10 substitutions are involved in attenuating the sabin 3 strain. the primary attenuating factor common to all three sabin vaccines is a mutation located in the virus's internal ribosome entry site, which alters stem-loop structures and reduces the ability of poliovirus to translate its rna template within the host cell. the attenuated poliovirus in the sabin vaccine replicates very efficiently in the gut, the primary site of infection and replication, but is unable to replicate efficiently within nervous system tissue. in 1961, type 1 and 2 monovalent oral poliovirus vaccine (mopv) was licensed, and in 1962, type 3 mopv was licensed. in 1963, trivalent opv (topv) was licensed, and became the vaccine of choice in the united states and most other countries of the world, largely replacing the inactivated polio vaccine. a second wave of mass immunizations led to a further dramatic decline in the number of polio cases. between 1962 and 1965, about 100 million americans (roughly 56% of the population at that time) received the sabin vaccine. the result was a substantial reduction in the number of poliomyelitis cases, even from the much-reduced levels following the introduction of the salk vaccine.
polio vaccine