Evolution of IgG antibody response against Toxoplasma gondii tissue cyst in acute and chronic human infections

• Main Authors: Margarita VILLAVEDRA, Hernán CAROL, Alberto NIETO
• Format: Article
• Language: English
• Published: Universidade de São Paulo 1998-03-01
• Series: Revista do Instituto de Medicina Tropical de São Paulo
• Subjects: T.gondii; Tissue cyst; Bradyzoite antigens; Diagnosis; Acute phase; Chronic phase
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0036-46651998000200003
• ISSN: 0036-4665; 1678-9946

The recognition profile of the tissue cysts antigens by IgG antibodies was studied during acute and chronic human toxoplasmic infection. Thus the IgG response against Toxoplasma gondii was investigated by immunoblotting in two patients accidentally infected with the RH strain as well as in group of naturally infected patients at acute and chronic phase. There was an overall coincidence of molecular mass among antigens of tachyzoites and tissue cysts recognized by these sera, however, they appear not to be the same molecules. The response against tissue cysts starts early during acute infection, and the reactivity of antibodies is strong against a wide range of antigens. Six bands (between 82 and 151 kDa) were exclusively recognized by chronic phase sera but only the 132 kDa band was positive in more than 50% of the sera analysed. A mixture of these antigens could be used to discriminate between the two infection phases. The most important antigens recognized by the acute and the chronic phase sera were 4 clusters in the ranges 20-24 kDa, 34-39 kDa, 58-80 kDa and 105-130 kDa as well as two additional antigens of 18 and 29 kDa. Both accidentally infected patients and some of the naturally infected patients showed a weak specific response against tissue cyst antigens.<br>O reconhecimento do perfil dos antígenos de cistos tissulares pelos anticorpos IgG foi estudado durante a infecção toxoplasmótica aguda e crônica. Assim a resposta de IgG contra Toxoplasma gondii foi investigada pelo "immunoblotting" em dois pacientes acidentalmente infectados com a variedade RH bem como em grupos de pacientes naturalmente infectados nas fases aguda e crônica. Houve uma coincidência global da massa molecular entre antígenos de taquizoitas e cistos tissulares reconhecidos por estes soros, todavia, eles parecem não ser as mesmas moléculas. A resposta contra cistos tissulares começa precocemente durante a infecção aguda e a reatividade de anticorpos é forte contra ampla variedade de antígenos. Seis faixas (entre 82 e 151 kDA) foram reconhecidas exclusivamente pelos soros da fase crônica mas somente as faixas de 132 kDA foram positivas em mais de 50% dos soros analisados. Uma mistura destes antígenos poderia ser usada para distinguir entre as duas fases da infecção. Os antígenos mais importantes reconhecidos nos soros das fases agudas e crônicas foram 4 grupos com intervalos de 20-24 kDa, 34-39 kDa, 58-80 kDa e 105-130 kDa bem como dois antígenos adicionais de 18 e 29 kDa. Ambos pacientes infectados acidentalmente e alguns dos pacientes naturalmente infectados mostraram fraca resposta específica contra os antígenos de cistos tissulares.