Invasion of the vector
salivary glands by
Plasmodium is a critical step for
malaria transmission. To describe
salivary gland cellular responses to
sporozoite invasion, we have undertaken the analysis of
Anopheles gambiae salivary gland transcriptome using Serial Analysis of
Gene Expression (SAGE).
Statistical analysis of the more than 160000
sequenced tags generated from four libraries, two from
glands infected by
Plasmodium berghei, two from
glands of controls, revealed that at least 57
Anopheles genes are differentially expressed in infected
salivary glands. Among the 37 immune-related genes identified by SAGE tags, four (Defensin1, GNBP, Serpin6 and Cecropin2) were found to be
upregulated during
salivary gland invasion, while five genes encoding small
secreted proteins display induction patterns strongly reminiscent of that of Cecropin2. Invasion by
Plasmodium has also an impact on the
expression of genes involved in transport,
lipid and
energy metabolism, suggesting that the
sporozoite may exploit the
metabolism of its host. In contrast, protein composition of
saliva is predicted to be only slightly modified after
infection. This study, which is the first
transcriptome analysis of the
salivary gland response to
Plasmodium infection, provides a basis for a better understanding of
Plasmodium/
Anopheles salivary gland interactions.
