This Article Full Text Full Text (PDF) Other Versions of this Article: CVI.00311-06v1 14/3/239    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lefevre-Pettazzoni, M. Articles by Rabilloud, M. Search for Related Content PubMed PubMed Citation Articles by Lefevre-Pettazzoni, M. Articles by Rabilloud, M.

 Previous Article  |  Next Article 

Clinical and Vaccine Immunology, March 2007, p. 239-243, Vol. 14, No. 3
1071-412X/07/$08.00+0     doi:10.1128/CVI.00311-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Impact of Spiramycin Treatment and Gestational Age on Maturation of Toxoplasma gondii Immunoglobulin G Avidity in Pregnant Women

Hospices Civils de Lyon, Hôpital de la Croix-Rousse, Service de Parasitologie, Lyon F-69317, France,¹ Hospices Civils de Lyon, Service de Biostatistique, Lyon F-69003, France; CNRS, UMR 5558 Equipe Biostatistique-Santé, Villeurbanne F-69100, France; and Université Lyon 1, UMR 5558 Laboratoire Biostatistique-Santé, Villeurbanne F-69100, France,² Laboratoire de Parasitologie, Mycologie Médicale et Pathologie Exotique, Equipe d'Accueil EA 3732, Université Lyon 1, UFR Médecine Lyon Nord, Lyon, France,³ Hospices Civils de Lyon, Centre Hospitalier Lyon-Sud, Laboratoire d'Immunologie, Pierre-Bénite F-69495, France⁴

Received 30 August 2006/ Returned for modification 13 October 2006/ Accepted 18 December 2006

The objective of the present study was to investigate the maturation of immunoglobulin G (IgG) avidity after Toxoplasma gondii seroconversion during pregnancy and the factors that affect IgG avidity over time. The study used 309 serum samples from 117 women and a multiple linear mixed regression analysis to show the patterns of variation of IgG avidity throughout gestation. The IgG avidity ratios and the patterns of their evolution with time were quite diverse among the women and were statistically heterogeneous (P = 0.011); however, the trend was toward a statistically significant increase (P < 0.0001). On average, a 1.0167-fold increase was observed for each additional gestational week after the putative date of infection. At 12 weeks after putative infection (the expected IgG avidity maturation time), the mean avidity ratio was 16.6% (95% confidence interval, 15.4 to 17.9%). At all times, the avidity ratio remained significantly heterogeneous among the women (P < 0.05); for 95% of them, that ratio ranged from 7.8 to 35.3% at 12 weeks after putative infection. Maternal age at the putative time of infection did not influence the maturation of IgG avidity. However, on average, a 1.009-fold decrease (P = 0.03) in that avidity was observed for each additional week of gestational age before infection and a 1.03-fold increase (P = 0.0003) was observed for each additional week of delay to the onset of spiramycin treatment. The rate of increase in the avidity ratio was lower if infection occurred late in pregnancy and higher if the delay to treatment was long. This information cannot allow accurate determination of the delay since the time of infection. The present results provide support for interpretation of the assay and caution against overinterpretation.

Published ahead of print on 3 January 2007.