Highly divergent hepaciviruses from African cattle

Area of Science:

• Virology
• Genomics
• Evolutionary Biology

Background:

• Hepatitis C virus (HCV) is a significant human pathogen.
• Unique hepaciviruses (HVs) have been identified in animal hosts, but HCV's direct ancestor remains unknown.
• The closest known animal HV relative to HCV was found in horses, prompting investigation into other livestock.

Purpose of the Study:

• To investigate the presence of HVs in African cattle populations.
• To characterize the genetic diversity and phylogenetic relationships of identified cattle HVs.
• To explore the evolutionary history and potential zoonotic implications of cattle HVs.

Main Methods:

• Analysis of cattle sera from Ghana using reverse transcription-polymerase chain reaction (RT-PCR).
• Near-full-genome sequencing of detected HV RNA.
• Phylogenetic analyses to determine evolutionary relationships and host shifts.

Main Results:

• Hepaciviruses (HVs) were detected in 8.5% of Ghanaian cattle sera, with high viral loads.
• Cattle HVs formed two distinct phylogenetic lineages, differing significantly in nucleotide sequence.
• Phylogenetic analyses indicated long-term circulation of HVs in cattle and suggested frequent host shifts within the Hepacivirus genus.
• Cattle HVs exhibited low genetic diversity compared to HCV genotypes, potentially influenced by human-modified ecologies.

Conclusions:

• Previously unknown hepaciviruses (HVs) circulate in African cattle at high prevalence.
• Cattle HVs are genetically divergent from other known HVs, including HCV.
• Evidence suggests centuries of HV circulation in cattle and frequent host shifts in Hepacivirus evolution.
• Further research is needed on cattle HV occurrence, pathogenicity, and zoonotic potential.