RESUMO
Polytransfused patients represent a major risk group for hepatitis C (HCV) acquirement. Haemophiliacs and thalassemic patients treated with virus contaminated blood or blood derivatives frequently exhibit anti-HCV antibodies and signs of chronic hepatitis. The serological profile for the HCV infection was investigated in 13 haemophiliacs, 18 cases of thalassemia and in 14 polytransfused patients affected by other diseases. The presence of anti-HCV antibodies was detected by means of the ORTHO HCV 3.0 ELISA kit and confirmed by Western-blot Murex. The serotyping used synthetic peptides mimicking the immunodominant epitopes in the NS4 region, characteristic of each of the six HCV genotypes in an ELISA blocking reaction (Murex). Serotype 1 was prevalent (51.1%), while serotype 2 was detected in 13.3% of patients, with a higher frequency in thalassemia cases. The remaining samples were multireactive, and serotype 3 alone was not detected. The profile of Western-blot bands was distinct for the monoreactive samples belonging to serotype 1 or 2. The analysis of the multireactive samples in young (thalassemic, age mean 15.17 +/- 6.5) and aged patients (haemophiliacs, age mean 32.64 +/- 13.5) allows us to suggest a different succession of reinfection acquirements. The infection with one of the subtypes does not confer protection against the reinfection with others. However, a certain attenuation of the symptomatology is obvious in the case of reinfections, indicating the existence of crossantigenic reactivities which contribute to protection. This protection is more evident in the case of primary infection with type 2 and is partially due to antigens coded by the NS4 genomic segment.