Sialotranscriptome sequencing and analysis of Anopheles sinensis and comparison with Psorophora albipes sialotranscriptome (Diptera: Culicidae)

Most of adult female mosquitoes secrete saliva to facilitate blood sucking, digestion and nutrition, and mosquito-borne disease prevention. The knowledge of classification and characteristics of sialotranscriptome genes are still quite limited. Anopheles sinensis is a major malaria vector in China and southeast Asian countries. In this study, the An. sinensis sialotranscriptome was sequenced using Illumina sequencing technique with a total of 10907 unigenes to be obtained and annotated in biological functions and pathways, and 10470 unigenes were mapped to An. sinensis reference genome with 70.46% of genes having 90%-100% genome mapping through bioinformatics analysis. These mapped genes were classified into four categories: housekeeping (6632 genes), secreted (1177), protein-coding genes with function-unknown (2646) and transposable element (15). The housekeeping genes were divided into 27 classes, and the secreted genes were divided into 11 classes and 96 families. The classification, characteristics and evolution of these classes/families of secreted genes are further described and discussed. The comparison of the 1177 secreted genes in An. sinensis in the Anophelinae subfamily with 811 in Psorophora albipes in the Culicinae subfamily show that six classes/subclasses have the gene number more than twice and two classes (uniquely found in anophelines, and Orphan proteins of unique standing) are unique in the former compared with the latter, whereas four classes/subclasses are much expanded and uniquely found in the Aedes class and is unique in the later. The An. sinensis sialotranscriptome sequence data is the most complete in mosquitoes to date, and the analyses provide a comprehensive information frame for further research of mosquito sialotranscriptome.