![]() ![]() ![]() To overcome these issues, vaccine researchers had, then, focused on increasing immunogenicity of oligosaccharides. For example, Hib CPS vaccine elicited poor immune responses in young children below 2 years of age and immune deficient peoples whom are the more prone to infections. Although native CPS vaccines were effective in controlling the incidence of diseases for people above 2 years of age, there were some troublesome immunological disadvantages. Inspired by the success of pneumococcal CPS vaccines, the tetravalent (A, C, W135 and Y) meningococcal, the Haemophilus influenza type b (Hib) and the Salmonella typhi Vi CPS-based vaccine were developed and licensed between 19 for adults and children older than 2 years in USA. Robert Austrian and his colleagues led to the development of 14-valent and 23-valent pneumococcal CPS-based vaccines that were licensed in 19, respectively. Meanwhile, the emergence of antibiotic resistant bacteria prompted the redirection of research efforts back to the vaccine development. Robert Austrian who was supported and motivated by the US National Institutes of Health (NIH) towards the development of possible pneumococcal polysaccharide vaccines. However, the field of pneumococcal vaccine research was kept alive by the persistent efforts of Dr. From 1950 to 1970, the antibiotics dominated the vaccine markets, and most research efforts focused on finding new antibiotics rather than developing vaccines. Unfortunately, those two vaccines were discontinued shortly after due to the introduction of new and extremely effective antimicrobial drugs such as penicillin, chlortetracycline, and chloramphenicol. ![]() Īfter several clinical tests of pneumococcal polysaccharides, two variants of pneumococcal vaccines containing six serotypes each were first licensed in USA in 1946. From 1942 to 1945, Heidelberger and his associates developed tetravalent vaccine, and the test in the US army air force was successful. Later studies by Finland and Ruegsegger furthered the development of pneumococcal capsular polysaccharide vaccines. In 1930, Francis and Tillett injected pure pneumococcal polysaccharides to patients and found CPS-specific antibodies in those patients. Then, between 19, Avery and Heidelberger at the Rockefeller Institute conducted a series of studies on capsular polysaccharides (CPS) of pneumococcus and discovered the immunogenicity of CPS. Carbohydrate-based vaccines have a long history, started from the isolation of capsular polysaccharide of Streptococcus pneumonia ( pneumococcus) by Dochez and Avery in 1917. ![]()
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