Distribution of fitness in populations of dengue viruses

Abstract

Genetically diverse RNA viruses like dengue viruses (DENVs) segregate into multiple, genetically distinct, lineages that temporally arise and disappear on a regular basis. Lineage turnover may occur through multiple processes such as, stochastic or due to variations in fitness. To determine the variation of fitness, we measured the distribution of fitness within DENV populations and correlated it with lineage extinction and replacement. The fitness of most members within a population proved lower than the aggregate fitness of populations from which they were drawn, but lineage replacement events were not associated with changes in the distribution of fitness. These data provide insights into variations in fitness of DENV populations, extending our understanding of the complexity between members of individual populations.

Figure 1. Phylogenetic analysis of the E gene of DENV-1 showing lineage extinction and replacement of DENV-1 in Myanmar.

Bootstrap values (100 replications) for key nodes are shown. A distance bar is shown below the tree. Lineage A, B and E are extinct and lineage C and D are still circulating. Strains selected for study have been highlighted.

Figure 2. Distribution of fitness within populations of DENV-1 from four lineages.

Populations are identified as strain/year/E (extinct) or C (circulating); proportion more fit than the population average indicated horizontal hatch, same fit as the original population indicated as bold squares and less fit than the original population indicated as small squares.