A detecção de Toxoplasma gondii no sangue venoso e na placenta de gestantes pela reação de polimerase em cadeia pode facilitar o diagnóstico pré-natal da toxoplasmose congênita. Foram avaliadas gestantes IgM-reagentes e os seus filhos. Além das dosagens de IgG, IgM, IgA e reação de avidez de IgG (MEIA), foram realizadas a técnica de imunoperoxidase e a inoculação em camundongos. De cada amostra foi efetuada amplificação gênica com primers do gene B1 e novos primers do gene TGR (chamados ABGTg7 C1 e N1). É preciso observar que o tratamento poderia ser responsável por uma diminuição da infecção. Desta forma, o diagnóstico negativo confirmaria a eficiência do tratamento preventivo na replicação parasitária no útero. A reação de polimerase em cadeia mostrou-se sensível e específica; evidenciou a presença de um a dez taquizoítas; pode ser utilizada com segurança e confiabilidade, além de tornar rápido o diagnóstico da toxoplasmose congênita, sendo, assim, ferramenta importante na avaliação pré-natal.

The Toxoplasma gondii detection in venous blood and placenta of pregnants by polymerase chain reaction may facilitate the diagnosis of congenital toxoplasmosis. We evaluated pregnants with reagent immunoglobulin M (IgM) and their children. Beyond serological toxoplasma-specific immunoglobulins G (IgG), M (IgM), A (IgA) and IgG avidity (MEIA), we did immunoperoxidasis and mice inoculation. Genomic amplification with gene B1 primers and new TgR primers (called ABGTg7 C1 and N1) was conducted for each sample. It's necessary to observe that treatment probably is responsible for the infection decrease, that manner, negative results would confirm uteri therapeutic efficiency. PCR was sensitive and specific, it identified one to ten tachyzoites. Besides being a fast form of congenital toxoplasmosis diagnosis, it may be used safely and trustly, as an important tool for congenital evaluation.

A slide micro-immunoenzymatic assay (micro-SIA) to detectantibodies to non-particulate Toxoplasma gondii antigens is described. This assay allows the diagnosis of toxoplasmosis infection in about 1 hr. Twenty-four determinations can be performed per slide. Five hundred ng of antigen and 5 or 10 µl drop of each reactive are necessary per well. The clear contrast of colours obtained for negative and positive sera after the test is finished, allows direct discrimination of the results. However, it is possible to quantify the results of the reaction using a minireader. Sera dilution cutoff value, determined as themost frequent titre for the general population, is 1:100. The toxoplasma micro-SIA correlates well with indirect immunofluorescence (IIF), its sensitivity is atleast three times as much as IIF. The test has an intra and inter assay variation coefficient of 5.46 per cent and of 6.24 per cent respectively. Sera obtained at random from argentinian people were analyzed and a 56 per cent of infection was found. The main features of the Toxoplasma micro-SIA are its simplicity, sensitivity, reproducibility, and the virtual absence of background making it very suitable for screening tests.

A rapid and simple technique for the purification of Toxoplasma gondii tachyzoites was developed. Highly purified parasites were obtained from the peritoneal exudates of infected mice by means of two consecutive discontinous sucrose gradients run at low speed (10,000xg, 30 min). Parasites obtained by this method conserved its biological activity. Hybridizations tudies with DNA from healthy mice and from purified tachyzoites preparations demonstrated that Toxoplasma gondii tachyzoites DNA could be obtained with better than 90 per cents purity. Preliminary studies with DNA endonucleases showed the presence in the tachyzoites genome of highly repetitives sequences.