Open AccessMolecular evolutionary studies of Lassa virus nucleoprotein 2
Author(s) -
Lawrence Ehis Okoror,
TA Eniolorunda,
OI Okoror
Publication year - 2011
Publication title -
asian pacific journal of tropical disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.208
H-Index - 33
ISSN - 2222-1808
DOI - 10.1016/s2222-1808(11)60007-8
Subject(s) - transversion , nonsynonymous substitution , genbank , biology , genetics , mega , phylogenetic tree , molecular evolution , nucleotide diversity , synonymous substitution , virology , gene , genotype , mutation , codon usage bias , physics , astronomy , genome , haplotype
Objective: To study the virulence diversity through molecular evolution, and to provide insight\udon circulating antibodies. Methods: The nucleotide sequences of 18 Lassa virus genomic RNA\udencoding Lassa virus nucleoprotein isolates collected from different parts of the world since the\udidentification of the Josiah strain were obtained from the GenBank and nucleotide substitution\udamong them studied using the computer program MEGA 4. The genetic distances among\udstrains were predicted by pairwise nucleotide differences. Results: The rate of synonymous\udsubstitution was high 5.889 per nucleotide per year and nonsynonymous was higher at 49.664.\udThe average predicted rate of synonymous and nonsynonymous using modified Nei-Gojobori\ud(assuming transition/transversion bias=2) was 27.9 which was taken as the genetic distance\udbetween strains. The average number of synonymous sites is 150.741 while the average number\udof nonsynonymous sites is 392.259. The phylogenetic tree was inferred by unweighted pairwise\udgrouping in MEGA4 and using neighbour-joining method. The time of emergence of Lassa\udvirus was predicted to be around January 1920. However, the first human appearance of the\udvirus was predicted to be around May (1 959暲24) months. In synonymous substitution the rate\udof (G-T) rare was high. The nucleotide frequencies were 0.314 (A), 0.246 (T/U), 0.204 (C) and 0.235\ud(G). The transition/transversion ratio k1=14.991 (purines) and k2=69.916 (pyrimidines). The overall\udtransition/transversion bias R=16.662 with a total of 620 position in the final data set. These\udfigures are far higher than an earlier study using Lassa virus glycoprotein. The nucleotide\uddiversity were also very high using the Taijima’s model in MEGA 4. Conclusions: The divergence\udwithin strains always coincides with the period of epidemic which goes to confirm that the\udcause of epidemic outbreak should be the emergence of new strain and also why the infection\udremains endemic despite circulating antibodies. A comparison with a similar study with the\udviral glycoprotein concludes that the glycoprotein is more suited for vaccine development