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Genetic diversity among Lassa virus strains.
M D Bowen1, P E Rollin, T G Ksiazek
1Special Pathogens Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Journal of Virology
|July 11, 2000
Summary
Lassa virus genetic diversity reveals four lineages, with Nigerian strains potentially ancestral to those in Guinea, Liberia, and Sierra Leone. Genetic distance correlates with geography, not time, in this large-scale analysis of Lassa fever virus.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Lassa virus causes Lassa fever, a significant hemorrhagic fever endemic in West Africa.
- Understanding Lassa virus genetic diversity is crucial for epidemiology and control efforts.
Purpose of the Study:
- To determine the genetic diversity and phylogenetic relationships among Lassa virus strains.
- To investigate the evolutionary patterns and geographic distribution of Lassa virus lineages.
Main Methods:
- Partial nucleoprotein (NP) gene sequencing of 54 Lassa virus strains.
- Phylogenetic analysis to establish evolutionary relationships.
- Development of a method for full-length S RNA amplification and cloning for NP and glycoprotein gene sequencing.
Main Results:
- Identified four distinct Lassa virus lineages, with three in Nigeria and one in Guinea, Liberia, and Sierra Leone.
- Observed significant genetic variation (up to 27% nucleotide, 15% amino acid) in the NP gene.
- Found genetic distance correlated with geographic distance, with no evidence of a molecular clock.
- NP genes showed higher variability than glycoprotein genes (GP1, GP2).
- Phylogenetic analysis suggested Nigerian strains may be ancestral to strains from other West African countries.
Conclusions:
- Lassa virus exhibits substantial genetic diversity across West Africa, structured into distinct lineages.
- Geographic factors play a significant role in Lassa virus evolution and diversification.
- Nigerian Lassa virus strains may represent an earlier evolutionary branch compared to strains from neighboring countries.