Differential Expression of Salivary Gland Genes in the Female Sand Fly Phlebotomus papatasi (Diptera: Psychodidae)

Saliva from blood-sucking arthropods modulates host homostasis and immunity, making salivary components potential candidates to be used against pathogens transmitted by these biting insects. Functional characterization of salivary molecules is fundamental to gain a better understanding into their roles during blood feeding and to determine under which conditions such molecules are expressed in the insect saliva. In the current study, we investigated the expression profile of 10 salivary genes from the sand fly Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae), a principal vector of Leishmania major. Our analyses using quantitative polymerase chain reaction were aimed at defining whether diet or senescence influences the expression of P. papatasi salivary gland-expressed genes in laboratory-reared female sand flies. Our results demonstrate that at least one of the most abundant salivary transcripts, SP44, is consistently modulated by either senescence or diet. In contrast, another abundant transcript, SP32, was expressed without any influence from the diet received or the age of the sand fly. Differential expression of the other eight transcripts was not consistently regulated by either diet or age, suggesting that other factors may have a greater influence on differential expression of these salivary gland proteins.