Frequent recovery and broad genotype 2 diversity characterize hepatitis C virus infection in Ghana, West Africa

Abstract

Hepatitis C virus (HCV) infection is thought to mostly become chronic and rarely resolves. HCV infection was serologically screened in 4,984 samples from Ghanaian blood donors, and 1.3% prevalence was found. At least 53% of confirmed anti-HCV carriers had no detectable viral RNA and were considered to have cleared the virus and recovered from the infection. Confirmation was authenticated by the presence of antibodies specific to at least two viral antigens, mostly NS3 and E2. Reactivity to HCV core antigens was lower in Ghanaian than United Kingdom blood donors. The minority of chronically infected donors carried a viral load significantly lower than an unselected comparative group of United Kingdom blood donors (2.5 x 10(5) versus 2.9 x 10(6) IU/ml; P = 0.004). HCV genotype 2 was largely predominant (87%). Sequence clustering was similarly broad in the E1/E2 and NS5 regions. The phylogenetic diversity and the incapacity to distinguish subtypes within genotype 2 in our and others' West African strains suggested that West Africa may be the origin of HCV genotype 2. The genetic diversity extended to the identification of strains clearly separated from known subtypes of genotype 2 and genotype 1. One strain appears to be part of a new HCV genotype. HCV infection in Ghana is characterized by a high rate of recovery and the predominance of broadly divergent genotype 2 strains.

FIG. 1.

Antigen reactivity of 43 HCV RNA-negative Ghanaian blood donations in two anti-HCV confirmatory assays.

FIG. 2.

RNA viral load in HCV-infected blood donors from Ghana and the United Kingdom. The horizontal bars denote median values.

FIG. 3.

Phylogenetic relationship between HCV E1/E2 sequences. The 23 Ghanaian sequences were aligned with 31 HCV reference strains from the GenBank data base. The six major lineages of HCV are indicated by the boldface numbers along the branches; reference strains are identified by their GenBank accession numbers, and subtypes of the viruses are also reported in parenthesis (classification according to Salemi and Vandamme [35]). The Ghanaian sequences determined in this study are indicated by boldface characters; only significant bootstrap values (≥80%) are shown.

FIG. 4.

Phylogenetic relationship between HCV NS5B sequences. The 21 Ghanaian sequences were aligned with the corresponding sequences from the 31 HCV reference strains shown in Fig. 3. The results are displayed as described in the legend for Fig. 3.

FIG. 5.

Alignment of E1/E2 amino acid sequences of five HCV Ghanaian variants. The sequences of ten clones were aligned for each variant, and the number of identical sequences is indicated on the left; for each variant, the major sequence was taken as reference. Residues identical to the major sequence are indicated by dashes. To facilitate the viewing, the HVR1 region is indicated; numbering of the residues starts at the NH2 terminus of E2.