Measles control in young infants.
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Biomedical subjects
Publications and source records attributed to N W Preston.
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Cholera vibrios can be allocated to one of three biotypes (classical, intermediate and El Tor), each of which can be sub-divided into two serotypes (Ogawa and Inaba). Vibriocidal tests with absorbed antisera have shown no evidence of biotype specificity in the killing of bacteria, but they have confirmed the role of the two serotype-specific antigens in immunity to cholera. The same presence of serotype specificity, and absence of biotype specificity, has been found by bacterial agglutination, an easier and quicker serological test. The use of this simpler test in ensuring a balanced serotype response to cholera vaccine is discussed, together with evidence that may lead to the production of more effective vaccine and better immunity.
Two large epidemics of pertussis occurred in Britain during 1977-79 and 1981-83, following a decline in vaccine uptake in the mid-1970s. Serotype 1,3 predominated during both epidemics but serotypes 1,2 and 1,2,3 constituted 32% (243 of 769) of the isolates from unvaccinated children compared with only 10% (9 of 86) of the isolates from vaccinated children (p < 0.005). Whole-cell vaccines, although effective against infection with all serotypes, have a higher efficacy against serotypes 1,2 and 1,2,3 than against serotype 1,3. These data suggest that not only should acellular vaccines contain agglutinogens specific for each serotype but trials should demonstrate efficacy against all three serotypes.
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When the three serotypes of Bordetella pertussis (types 1,2,3; 1,2 and 1,3) were labelled with agglutinins and protein-A gold, agglutinogen 1 was found on fimbriae and on the cell surface of types 1,2,3 and 1,2 but on the cell surface only of non-fimbriate type 1,3 organisms. In contrast, agglutinogen 2 was located on fimbriae only. Agglutinogen 3 was not labelled. When protein-A gold was replaced by immunoglobulin-G gold, agglutinogen 3 was found on the cell surface only, even of fimbriate bacteria of type 1,2,3. The implications of these findings for acellular vaccines are discussed.
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After the decline in pertussis vaccination in Britain from the mid-1970s, isolates possessing agglutinogen 2 (types 1.2.3 and 1.2) have replaced type 1.3 as the predominant serotypes. These agglutinogen-2 strains are fimbriate, and their predominance in non-vaccinated communities may result from enhanced attachment to mucosal cells. However, type 1.3 cells are not fimbriate; and, because agglutinogen 3 is essential in fully effective whole-cell vaccine, a subcellular vaccine prepared from fimbriae alone (agglutinogen 2) would probably be inadequate. The mouse can be killed with type 1 strains, devoid of agglutinogens 2 and 3, and is therefore not a suitable model for ensuring that pertussis vaccine contains these essential immunogens.
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