Kinetics and sensitivity of ELISA IgG pertussis antitoxin after infection and vaccination with Bordetella pertussis in young children.
Sera from 96 young children in a vaccine trial were analysed for kinetics of ELISA IgG anti-pertussis toxin (anti-PT) after a laboratory-verified pertussis infection. The antibody decay curves after infection were biphasic and similar in shape to those after vaccination. The change from a rapid to a slower decay after the peak occurred about 4-5 months from the first day of cough. In a group of children given a two- or a five-component acellular pertussis vaccine the proportion of sera above the tentative cut-off values for anti-PT of 20, 50 or 100 EU/ml 12 months after onset of the infection were 19%, 0% and 0% respectively. Corresponding figures for a whole-cell or placebo vaccine group of infected children were significantly higher, 73%, 39% and 30%, i.e. the antibody decay after infection in young children depends on vaccination status as well as on the pertussis vaccine given. In a large group of non-infected children vaccinated with the same five-component acellular vaccine 13%, 0% and 0% had sera above 20, 50 and 100 EU/ml at 12 months after the third vaccine dose and all were below the minimum level of detection 2 years after vaccination. In conclusion, knowledge about anti-PT kinetics is essential for the interpretation of seroepidemiological data but hardly offers the possibility to establish valid cut-off values for anti-PT in single sample serology. An option would be to identify a grey zone between the positive and negative ends of the distribution for follow-up testing by a second serum.
Swedish Institute for Infectious Disease Control, Solna, Sweden. hans.hallander@smi.se
Hans O
HO
Hallander
Margaretha
M
Ljungman
Jann
J
Storsaeter
Lennart
L
Gustafsson
D000907:Antibodies, Bacterial / Q000097:blood; D001886:Bordetella pertussis / Q000276:immunology*; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007223:Infant; D007700:Kinetics; D015999:Multivariate Analysis; D010567:Pertussis Vaccine / Q000276:immunology* / Q000592:standards; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014611:Vaccination / Q000592:standards*; D022282:Vaccines, Acellular / Q000276:immunology / Q000592:standards; D014917:Whooping Cough / Q000276:immunology* / Q000517:prevention & control
D000907:Antibodies, Bacterial; D010567:Pertussis Vaccine; D022282:Vaccines, Acellular