Trofozoítos obtidos de cultura de Entamoeba histolytica isoladas e axenizadas no Brasil (ICB-CSP, ICB-462 e ICB-32) foram utilizados para a produção de soros imunes em coelhos e para a caracterização de antígenos através dos seus perfis eletroforético e glicoproteico, em paralelo com uma cepa padrão isolada e axenizada nos Estados Unidos (HK-9). Obtiveram-se soros hiperimunes, reativos frente aos antígenos homólogos e heterólogos. As quatro cepas em estudo apresentaram perfis eletroforético e glicoproteico complexos e semelhantes, compostos por polipeptídeos com pesos moleculares variando de 200 kDa a menos de 29 kDa. Não se detectaram diferenças significativas entre as cepas patogênicas e não patogênicas.

Trophozoites from cultures of Entamoeba histolytica strains isolated and grown axenically in Brazil (ICB-CSP, ICB-462 and ICB-32) were used for immune sera production and for characterization of their antigens by using electrophoretic and glycoproteic profiles, in parallel with a standard strain isolated and kept under axenic conditions in USA (HK-9). Hyperimmune sera, presenting high antibody titers with homologous and heterologous antigens, were obtained. The four strains in study revealed similar and complex electrophoretic and glycoproteic profiles showing polypep-tides with molecular weights ranging from 200 to less than 29 kDa. No significant differences were detected between the pathogenic and non-pathogenic strains.

In two distinct experiments, immature S. mansoni worms (LE strain, Belo Horizonte, Brazil), aged 20 days, obtained from the portal system of white outbred mice, were irradiated with 14 and 4 Krad, respectively. Afterwards, the worms were directly inoculated into the portal vein of normal mice. Inoculation was performed with 20 irradiated worms per animal. Fifty days after inoculation, the mice that received 4 and 14 Krad-irradiated worms and their respective controls were infected with S. mansoni cercariae (LE strain), by transcutaneous route. Twenty days after this challenge infection, the animals were sacrificed and perfused for mature irradiated (90-day-old) and immature (20-day-old) worm counts. Analysis of the results showed that statistically significant protection against cercariae occurred in both groups with irradiated worms.

Tentou-se obter imunoproteção contra infecção cercariana pela inoculação de vermes vivos na cavidade peritoneal de camundongos. Embora os vermes sobrevivessem bem nestas condições e não ocorresse postura de ovos, não foi possível obter imunoproteção, Também a inoculação de ovos viáveis por via sangüínea e peritoneal não propiciou o aparecimento de imunoproteção nos camundongos com vermes na cavidade peritoneal.

An attempt has been made to induce immunoprotection against cercarial infection through inoculation of live worms into the peritoneal cavity of mice. Although the worms were able to survive normally under these conditions, and no egg-laying could be detected, immunoprotection was obtained. Likewise, the inoculation of viable eggs, by circulatory and peritoneal routes, did not provide immunoprotection in mice with worms in the peritoneal cavity.