Variability of the envelope regions of HCV in European isolates and its significance for diagnostic tools.

Following the original description of HCV in 1989 a tremendous amount of sequence data is now available. Based on the 8 complete nucleotide sequences published so far at least 4 genotypes can be distinguished. Partial sequences of additional HCV isolates indicate the existence of further genotypes. A serological typing is not yet possible. For detection of virus, reverse transcription and amplification of the 5' non coding region is most commonly performed. This region of the genome is highly conserved among all isolates. In this study we used regions of the E1 and E2 gene in order to classify HCV isolates. The nucleotide sequences of regions in E1 and E2 gene of different European isolates from Germany, Croatia, Hungary, and Rumania were determined and compared to recently published RNA sequences of American and Japanese HCV isolates. The cDNA, obtained by reverse transcription of viral RNA extracted from sera was amplified by nested PCR, cloned and sequenced. Within 564 nucleotides (nt) of E1 we found 87-90% homology (and 89-92% homology at aa level) compared to sequences of Japanese origin and 73-74% homology (77-81% at aa level) compared to the prototype HCV sequence (ptHCV-I). In all characterized isolates the sequence of E2 (643 nucleotides) showed a homology of about 83% at the nucleotide level as compared to genotype II sequences, and a homology of about 70% to genotype I. Our results confirm the existence of two hypervariable regions in the E2 gene of genotype II sequences. Our results also indicate together with other reports from European HCV isolates that genotype II is predominant in Europe.