Sequencing of Culex quinquefasciatus establishes a platform for mosquito comparative genomics

Abstract

Culex quinquefasciatus (the southern house mosquito) is an important mosquito vector of viruses such as West Nile virus and St. Louis encephalitis virus, as well as of nematodes that cause lymphatic filariasis. C. quinquefasciatus is one species within the Culex pipiens species complex and can be found throughout tropical and temperate climates of the world. The ability of C. quinquefasciatus to take blood meals from birds, livestock, and humans contributes to its ability to vector pathogens between species. Here, we describe the genomic sequence of C. quinquefasciatus: Its repertoire of 18,883 protein-coding genes is 22% larger than that of Aedes aegypti and 52% larger than that of Anopheles gambiae with multiple gene-family expansions, including olfactory and gustatory receptors, salivary gland genes, and genes associated with xenobiotic detoxification.

Fig. 1

A) Codon-based estimates of DNA substitutions along the mosquito phylogeny, C. quinquefasciatus (Cq), Ae. aegypti (Aa), and An. gambiae (Ag) with D. melanogaster (Dm) as an outgroup. Dates of divergence were taken from previous studies (6). B) Chromosomal synteny between C. quinquefasciatus, Ae. aegypti, An. gambiae and D. melanogaster. Plain lines indicate main orthologous chromosomes and dashed lines secondary orthologous chromosomes. Colors indicate syntenic chromsome arms. Chromosomes not to scale. C) Orthology delineation among the protein-coding gene repertoires of the three sequenced mosquito species. Categories of orthologous groups with members in all three species include single-copy orthologs in each species (1:1:1), and multi-copy orthologs in all three (N:N:N), one (N in 1), or two (N in 2) species. Remaining orthologous groups include single or multi-copy groups with genes in only two species (X:X:0, X:0:X, 0:X:X). The remaining fractions in each species (Cq/Aa/Ag-specific) exhibit no orthology with genes in the other two mosquitoes.