Evolution of hypervariable region 1 (HVR1) of hepatitis C virus in chronic infected children

GISMONDI MI; STAENDNER L; GUZMÁN CA; GRINSTEIN S; PRECIADO MV

Cancún

Congreso; 11th International Congress on Infectious Diseases; 2004

American Society for Infectious Diseases

Hepatitis C virus (HCV) infection in children is uncommon and its natural history is still unknown. HVR1 is a highly variable, 27aa immunogenic region of HCV envelope glycoprotein E2. HCV quasispecies displaying diverse HVR1 sequences are detected in chronic HCV-infected patients. HVR1 variability has been associated with viral persistence in adults. Our aim was to evaluate HVR1 evolution in HCV-infected children during follow-up to characterize viral persistence. This study included 5 immunocompetent patients (initial age 2-13 years). Main risk factors for HCV transmission were: 2/5 mother HCV+, 1/5 blood transfusion and 2/5 sporadic cases. Twenty three plasma samples from all patients were obtained at regular intervals during follow-up (2-3½ years). A 348bp fragment encompassing HVR1 was amplified by nested RT-PCR. Amplicons were 1) purified and directly sequenced, and/or 2) cloned into pCR 2.1&#174 vector followed by transformation of competent E.coli DH5a and blue-white selection of recombinant colonies. Plasmid DNA was isolated and inserts were purified, subjected to SSCP to analyze their heterogeneity and sequenced. HCV viral load, serum ALT values and liver biopsy were also analyzed. Serum ALT values were raised in 4 patients. Mean HCV viral load was 5.68 $#177 0.35 IU/mL. Liver biopsy evaluation showed signs of chronic hepatitis and fibrosis in all patients. High diversity of HVR1, as determined by SSCP and DNA sequencing, was observed in samples corresponding to 3/5 patients. Interestingly, HVR1 sequence was conserved in samples corresponding to 2 vertically infected patients (follow-up periods of 27 and 42 months). HCV persistence was characterized by high levels of viral load and fibrosis in all patients studied. Quasispecies variation over time in 3 patients might be consequence of the selective pressure exerted by the host’s immune system. The conservation of HVR1 sequence in 2 patients infected vertically suggests an immunotolerance status that might facilitate viral persistence.