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MODELS OF INFECTION |
Groupe Immunité des Muqueuses et Agents Pathogènes (GIMAP), Faculté de Médecine Jacques Lisfranc, 15 rue Ambroise Paré, 42023 Saint Etienne, France and *Unité d'Immunologie et de Physiologie, Département de Biologie, Faculté des Sciences et Techniques, Avenue A. El Khattabi, BP 618, 40000 Marrakech, Morocco
Corresponding author: Dr P. Flori (e-mail: pierre.flori{at}univ-st-etienne.fr).
Received 14 Dec. 2001; revised version received 3 April 2002; accepted 4 April 2002.
Maternofetal transmission of Toxoplasma gondii was assessed in pregnant guinea-pigs, with a gestational period of 65 ± 5 days. A total of 56 female guinea pigs was infected by the intraperitoneal route (RH strain), by the oral or the intraperitoneal route (Prugniaud strain; PRU) or by the oral route (76K strain). Inoculation was performed 90 ± 18 days or 30 ± 9 days before the onset of gestation or 20 ± 6 days or 40 ± 6 days after. Gestational age was determined by a progesterone assay. Parasite loads (fetal brain and liver) were assessed by nested PCR and real-time PCR quantification on Light Cycler® was performed with a SYBR Green I® technique. The 76K strain appeared to be the most virulent in the model: the neonatal survival rate was 31%, in contrast to 53% and 68% for the PRU and RH strains, respectively. The percentage of survival of neonates for all strains taken together was lower after inoculation at 40 days gestation (25%) than at 20 days gestation (77%). Whatever the strain, maternofetal transmission determination was greater with nested PCR (54% for RH, 84% for PRU and 86% for 76K strains) than with real-time quantitative PCR (31% for RH, 66% for PRU and 76% for 76K strains). However, real-time quantitative PCR showed that neonatal parasite load was greater with the cystogenic strains (76K, PRU) and that high hepatic load (>10 000 parasites/g) was often associated with disease severity (11 of 12 cases). Therefore, this technique may provide an important element in understanding this congenital disease.
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