Is hepatitis C virus genotype 4 predominant in Saudi Arabia?

Hepatitis C virus (HCV) genotype 4 is believed to be predominant in the Mid dle East including Saudi Arabia (SA). We attempted to genotype 80 HCV isola tes from different parts of SA by direct sequencing of a variable 222bp fra gment from the NS5B region. The phylogenetic analysis of the NS5B sequences was complemented by direct sequence analysis of the conserved 5'-NCR regio n for HCV type-specific polymorphism. All 80 NS5B sequences separated into 3 clades which comprised 6 type 1b variants, 30 type 4 variants (24 of type 4a and 6 of type 4c or d) and 44 type 3 variants. Apart from two definitiv e type 3b variants the other 42 type 3 NS5B sequences formed 4 clusters wit h low similarity to type 3a-f HCV sequences from the database. The precise subtyping of these 42 type 3 variants awaits sequencing of longer HCV RNA s tretches. Our results indicate that HCV type 4 may not be the only dominant genotype in SA.