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New HCV genotype subtypes present in sub-Saharan Africa

Researchers discovered diverse hepatitis C genotype 4 strains and new genotype 7 strains in sub-Saharan African countries with NS3 and NS5A polymorphisms associated with resistance to direct-acting antivirals in other genotypes, according to recently published data.

“While DAAs are cheap to manufacture and generic formulations are being rapidly developed, several barriers may hinder efforts to eradicate the virus,” Chris Davis, MD, from the University of Glasgow Center for Virus Research in Scotland, and colleagues wrote. “A lack of knowledge about strains circulating in [sub-Saharan Africa (SSA)] could affect treatment outcome.”

According to Davis and colleagues, seven HCV genotypes have been identified to date with a total of 84 subtypes, many of which were identified in high-income countries. Additionally, researchers have recently identified four sequences that fulfill the criteria for genotype 8.

“Encouragingly, pan-genotypic combinations of anti-viral drugs have recently been licensed; these have wide-ranging activity against the HCV subtypes present in high income countries (HICs), but have been less well assessed in the context of strains present in low and middle-income countries (LMICs), particularly in SSA,” Davis and colleagues wrote.

The researchers sequenced samples from patients in Uganda and the Democratic Republic of Congo. Patients were either positive for HCV antibody and HCV RNA or RNA-negative but seropositive.

Results revealed 12 patients with genotype 4 — including the subtypes 4k, 4v, 4q and 4s — and three patients with genotype 7. Regarding genotype 7, the researchers found two “highly divergent” genotypes that likely represent new subtypes, “although confirmation of a new HCV subtype requires the identification of at least two strains for each subtype,” they wrote.

There was no evidence of recombination within the divergent genotype 7 sequences.

“In sub-Saharan Africa, approximately 11 million people are infected, the majority with genotypes that have received little or no attention in clinical treatment or vaccine trials, and it is likely that new genotypes remain undiscovered,” Davis and colleagues wrote. “There is a need to understand more about the diversity of viruses in [Democratic Republic of Congo], Uganda and other countries in SSA due to the potential impact of viral genetic diversity on diagnostic assay sensitivity, treatment response rates and vaccine design.” – by Talitha Bennett

Disclosure: Davis reports no relevant financial disclosures. Please see the full study for the other authors’ relevant financial disclosures.