Parasite load in guinea pig foetus with real time PCR after maternofoetal transmission of toxoplasma gondii

Parasite loads of different tissues were assessed in guinea pig foetus after maternal infection. Twelve female guinea pigs were infected with 100 cysts of the 76 K strain of Toxoplasma gondii by the oral route. Inoculation was performed 20 ± 5 days (G20) or 40 ± 5 days (G40) after the beginning of gestation. Gestational age was determined by progesterone assay. Maternal and foetal organ samples were taken 60 days after the beginning of gestation. Parasite loads (from placenta, amniotic fluid (AF), cord blood (CB), foetal brain, liver, lung and spleen) were assessed by a real-time PCR quantification using fluorescence resonance energy transfer (FRET) hybridization probes on the Light Cycler®. Congenital transmission was proven by the presence of parasites in blood or tissue samples of the foetus in 84.6% (11/13) and 100 % (16/16) of cases after inoculation on G20 and G40 , respectively. The quantitative analysis of our results after inoculation at G20 and G40 has allowed us to determinate the positive parasitic loads as a function of the origin of the sample and the period of inoculation. The parasite loads expressed as log (parasite/g) were low in AF and CB samples: 1.49 ± 0.50 and 1.05 ± 0.10 at G20 and 1.21 ± 0.36 and 1.20 ± 0.42 at G40 respectively. In contrast the placenta and the different foetal tissues had higher parasite burdens: 2.89 ± 0.54 to 5.30 ± 0.51 at G20 and 2.81 ± 0.71 to 3.65 ± 0.59 at G40 . All the placentae were positive for parasites even in the two cases with no proven transmission. Real time quantitative PCR using the hybridization probe was a very sensitive and reproducible technique to study the kinetics of congenital toxoplasmosis in the guinea pig model wich is close to that of humans

Parasite load in guinea pig foetus with real time PCR after maternofoetal transmission of

Parasite loads of different tissues were assessed in guinea pig foetus after maternal infection. Twelve female guinea pigs were infected with 100 cysts of the 76 K strain of Toxoplasma gondii by the oral route. Inoculation was performed 20 ± 5 days (G20) or 40 ± 5 days (G40) after the beginning of gestation. Gestational age was determined by progesterone assay. Maternal and foetal organ samples were taken 60 days after the beginning of gestation. Parasite loads (from placenta, amniotic fluid (AF), cord blood (CB), foetal brain, liver, lung and spleen) were assessed by a real-time PCR quantification using fluorescence resonance energy transfer (FRET) hybridization probes on the Light Cycler®. Congenital transmission was proven by the presence of parasites in blood or tissue samples of the foetus in 84.6% (11/13) and 100 % (16/16) of cases after inoculation on G20 and G40 , respectively. The quantitative analysis of our results after inoculation at G20 and G40 has allowed us to determinate the positive parasitic loads as a function of the origin of the sample and the period of inoculation. The parasite loads expressed as log (parasite/g) were low in AF and CB samples: 1.49 ± 0.50 and 1.05 ± 0.10 at G20 and 1.21 ± 0.36 and 1.20 ± 0.42 at G40 respectively. In contrast the placenta and the different foetal tissues had higher parasite burdens: 2.89 ± 0.54 to 5.30 ± 0.51 at G20 and 2.81 ± 0.71 to 3.65 ± 0.59 at G40 . All the placentae were positive for parasites even in the two cases with no proven transmission. Real time quantitative PCR using the hybridization probe was a very sensitive and reproducible technique to study the kinetics of congenital toxoplasmosis in the guinea pig model wich is close to that of humans

Downy mildew resistance evaluation in 28 grapevine hybrids promising for breeding programs in Trentino region (Italy)

Downy mildew is a major grapevine disease caused by the biotrophic oomycete, Plasmopara viticola. Numerous disease resistance studies of diverse Vitis germplasm have been previously carried out to identify downy mildew resistance sources; however, ratings were mainly reported using leaf disc in vitro testing and foliage field assessment, or upon leaf and cluster field evaluations. In the current study, 28 grapevine hybrid cultivars were screened using leaf disc bioassay, for disease resistance characterization of both existing and wild-collected materials. 16 hybrids were identified as highly resistant or resistant, and will serve as relevant resistance donors in future pre-breeding and breeding programs. All grapevine hybrids were evaluated for foliar and cluster downy mildew resistance in an untreated field trial over three successive years. This study showed that the leaf disc bioassay provided some information on the resistance level of the genotypes under scrutiny, but it was a weak predictor of their resistance level under field conditions on leaves and even more on bunches. These findings are relevant to future applications in both traditional and marker-assisted breeding programs which promote sustainable viticulture