Abstract

Background: Sand fly saliva can drive the outcome of Leishmania infection in animal models, and salivary
components have been postulated as vaccine candidates against leishmaniasis. In the sand fly Phlebotomus
papatasi, natural sugar-sources modulate the activity of proteins involved in meal digestion, and possibly influence
vectorial capacity. However, only a handful of studies have assessed the variability of salivary components in sand
flies, focusing on the effects of environmental factors in natural habitats. In order to better understand such
interactions, we compared the expression profiles of nine P. papatasi salivary gland genes of specimens inhabiting
different ecological habitats in Egypt and Jordan and throughout the sand fly season in each habitat.
Results: The majority of investigated genes were up-regulated in specimens from Swaymeh late in the season,
when the availability of sugar sources is reduced due to water deprivation. On the other hand, these genes were
not up-regulated in specimens collected from Aswan, an irrigated area less susceptible to drought effects.
Conclusion: Expression plasticity of genes involved with vectorial capacity in disease vectors may play an
important epidemiological role in the establishment of diseases in natural habitats.