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The effect of adding 500 micrograms of (2,6-0-dimethyl) beta-cyclodextrin (Me-beta-CD) per ml of Stainer-Scholte (SS) medium in two-day shaker flask cultures of Bordetella pertussis on the production of lipopolysaccharide (LPS) was investigated. The amount of LPS per 10(9) cells found in the supernatants of these cultures was either somewhat reduced or unaffected by comparison with the amounts in cultures grown in SS-medium alone. In addition, the time course of LPS release from cultures of B. pertussis strain 3843 cells during a 96-h growth period in normal and Me-beta-CD-enriched SS medium is described. By using the enriched medium bacterial growth, the production of filamentous haemagglutinin (FHA) and of pertussis toxin (Pt) and the levels of haemagglutination and lymphocytosis-promoting activity were enhanced to various degrees. Measurements made on sedimented whole and on sonicated B. pertussis cells grown in the two media showed no differences in LPS content. The reasons for the reduced/unaffected LPS production are discussed. It has been suggested that an interaction between hydrophobic cavities of the Me-beta-CD molecules and the 'lipid A' part of LPS reduces the reactivity of LPS in the Limulus Amoebocyte Lysate (LAL) assay. This possibility, however, was rejected as the reactivity of Me-beta-CD-spiked purified B. pertussis strain 3803 LPS, compared with unspiked samples, remained unchanged.

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Data on the epitope specificity of 10 monoclonal hybridoma antibodies (Mabs) that showed positive reaction in enzyme-linked immunosorbent assay (ELISA) towards pertussins toxin (Ptx) are presented. The relative functional affinity of the Mabs was determined in a catching ELISA system. The Mabs were tested for their ability to inhibit the biological activities of this toxin in two in vitro systems, viz. haemagglutination (HA) and Chinese Hamster Ovary cell (CHO) test, and in three in vivo assays: histamine sensitization (HS), leucocytosis-promoting activity (LP) and protection against intra-cerebral challenge (i.c.) with virulent B. pertussis organisms. Four Mabs were found inhibiting HA and three inhibited the effect on CHO cells. Two Mabs showed demonstrable protective effect on mice in i.c. test. The same two Mabs were also able to inhibit HS and LP activity of Ptx. Five of the ten Mabs reacted with Ptx subjected to blotting after separation of the toxin subunits in sodium-dodecyl sulphate polyacrylamide gel electrophoresis. The five Mabs all bound to more than one subunit. The epitopes defined by several of the Mabs might be useful in the context of a third-generation whooping cough vaccine.

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Pertussis whole cell bacterial vaccine was injected in mice during early pregnancy to disclose any teratogenic effect on the brain of the fetuses. Cytochalasin D by itself induced exencephaly in a dose dependent way in fetal mice. When pregnant mice received a single injection of pertussis vaccine on day 8 of gestation and a subteratogenic dose of cytochalasin D on days 8, 9 and 10 of gestation a synergistic teratogenic action of pertussis vaccine and cytochalasin D in mice was observed. When autopsy was performed after a further 9 to 10 days a significant number of brain malformations was found. In order to analyse which component in the vaccine might be responsible for the co-teratogenic effect, purified pertussis components, pertussis toxin and filamentous haemagglutinin were used in combination with cytochalasin D, but no malformations occurred. The same results were obtained by using diphtheria-tetanus-polio (DiTePol) vaccine and acellular pertussis component vaccine, whereas the use of whole cell typhoid vaccine resulted in a high rate of fetuses with exencephalies. Experiments with purified Bordetella pertussis and Escherichia coli lipopolysaccharides indicated that lipopolysaccharides in whole cell pertussis vaccine as well as in typhoid vaccine were the factors causing teratogenicity in fetal mice.

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Animal models to control the serious neurological complications after vaccination against whooping cough are not available. In a recent paper pertussis vaccine induced acute encephalopathy in certain mouse strains (1). Healthy BALB/c mice died with shock-like symptoms after immunization with bovine serum albumin (BSA) and heat-killed pertussis. Mice not sensitized with BSA survived, and mice of strains with another H-2 type than H-2d were not susceptible. The authors concluded that the susceptibility to side effects to pertussis vaccine in mice and possibly in human is linked to the MHC. We tried to repeat the experiments reported by Steinman et al. in the hope that the murine encephalopathy model would be useful to evaluate possible neurological complications. In spite of having the same H-2d genotype, the BALB/c mice of two breeding stocks did not develop shock-like symptoms with fatal consequences after the last injection with BSA. This fact corresponds possibly with the author's observation that the pertussis vaccine encephalopathy is not under the control of H-2 genes alone. As shown in our tests the sudden deaths and encephalopathy in mice are not linked to BSA-sensitization because mice who received pertussis vaccine only showed the same symptoms as mice injected with BSA and vaccine. Histology did not indicate brain damage. It seems obvious that the deaths in our experiments were caused by the pertussis toxins present in the large numbers of bacteria given.

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