الفهرس 
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Abstract
Plasmodium (P.) parasites undergo a sequential series of developmental changes as they traverse and invade various tissues of both vertebrate and invertebrate hosts. These developmental changes are reflected in the parasites’ morphology, infectivity, gene expression patterns, and levels. The studies of P.–mosquito salivary gland interactions are severely limited by the lack of experimental ex vivo or in vitro systems. The mosquito factor(s) triggering those developmental changes during and post salivary gland invasion are largely unknown. Using an ex vivo Anopheles (An.) stephensi salivary gland culture system incorporating simple microfluidics and transgenic P. berghei PbANKA-Cherry-2204c1 with the fluorescent protein gene mCherry under the transcriptional control of the Pbuis4 promoter whose expression served as a proxy for parasite maturation, sporozoites pre- and post-salivary gland invasion in vivo and the developed ex vivo system have been investigated. Rapid parasite maturation has been observed in the absence of salivary gland invasion. While in vivo mCherry expression was only detectable in sporozoites within the salivary glands (mature parasites) as expected, the simple exposure of P. berghei sporozoites to dissected female An. stephensi salivary glands led to rapid parasite maturation as indicated by mCherry expression. The data obtained from using female An. stephensi salivary gland homogenates show the expression of mCherry protein in about 70% of treated
sporozoites in vitro. Anopheles stephensi midgut homogenates as a non-specific tissue and Aedes (Ae.) aegypti salivary gland homogenates as a non-vector tissue were used and the UIS4, UIS7, and mCherry genes expression were compared with the salivary gland and midgut sporozoites. Sporozoites treated with Ae. aegypti salivary gland homogenates have a transcription profile of the tested genes like that of salivary gland sporozoites. These results suggest that previous efforts to develop ex vivo and in vitro systems for investigating sporozoite interactions with mosquito salivary glands have likely been unsuccessful in part because the maturation of sporozoites leads to a loss in the ability to invade salivary glands. The obtained findings give the reason for the failure of the previous trials to develop sporozoite invasion of salivary glands in vitro. Thus, it is challenging to develop salivary gland invasion in an ex vivo system model. Although the role of the salivary gland as a gateway and its invasion is the most critical and specific step in the disease transmission, the results indicate that the factor(s) triggering P. development following mosquito salivary gland invasion are not affected by mosquito species nor its vector capacity and belong to salivary gland physiological and molecular properties.