Dynamics and Fitness Cost of Genetically Engineered Entrobacter cloacae Expressing Defensin for Paratransgenesis in Phlebotomus papatasi

Abstract

Background: Enterobacter cloacae subsp. dissolvens bacterium is a known commensal of the gut microflora of Phlebotomus papatasi, the main vector for zoonotic cutaneous leishmaniasis, and nominated for paratransgenesis in sand flies. In this study, we evaluated dynamics and fitness costs of engineered E. cloacae for its potential to serve as a 'Trojan Horse' in P. papatasi. Methods: The engineered strain of E. cloacae transformed with a constantly active expressed red fluorescent protein plus defensin (EC-DR) plasmid and was fed to sand fly colonies via larval food to larvae. A wild type the bacterium (EC-WT) and intact food were used as controls. Fitness characters as well as dynamics of the EC-DR at various development stages of sand fly larvae were tested by plating homogenized specimens and counting fluorescent expressing colonies on the Tet-BHI agar medium. Results: Enterobacter cloacae DR producing red fluorescent protein could be isolated from the larvae gut after 36 days when the bacteria were added once in larval pots. The EC-DR with multiple applications had no negative effect on emergence time of instar II larvae, pupae, and adults but increased slightly mortality rate of P. papatasi larvae. The experiment also confirmed lack or weak trans-stadial transmission of E. cloacae DR in P. papatasi. It has minimal fitness cost on P. papatasi feeding behavior and survival. Conclusion: Results of this study showed that E. cloacae DR is suitable for paratransgenesis of P. papatasi at only adult stage because it did not transmit transstadially.

Influence of inoculated gut bacteria on the development of Bactrocera dorsalis and on its susceptibility to the entomopathogenic fungus, Metarhizium anisopliae

“…The shortest larval development period was recorded in flies with an intact microbiome as well as in the P. alcalifaciens line whereas the longest period was recorded in the E. cloacae fly line. In other insects, E. cloacae has been shown to stimulate the host's immune responses which can protect the host from other pathogens or in some others it causes pathogenesis and mortality [51][52][53]. In B. dorsalis, this bacterium has been reported to increase fecundity but lower the longevity of adult flies [39].…”

Influence of inoculated gut bacteria on the development of Bactrocera dorsalis and on its susceptibility to the entomopathogenic fungus, Metarhizium anisopliae

“…The shortest larval development period was recorded in ies with an intact microbiome as well as in the P. alcalifaciens line whereas the longest period was recorded in the E. cloacae y line. In other insects, E. cloacae has been shown to stimulate the host's immune responses which can protect the host from other pathogens or in some others it causes pathogenesis and mortality [53][54][55]. In B. dorsalis, this bacterium has been reported to increase fecundity but lower the longevity of adult ies [39].…”

Influence of Bactrocera Dorsalis Larval Gut Bacteria on its Susceptibility to the Entomopathogenic Fungus, Metarhizium Anisopliae

“…The shortest larval development period was recorded in ies with an intact microbiome whereas the longest period was recorded in the E. cloacae y line. In other insects, E. cloacae has been shown to stimulate the host's immune responses which can protect the host from other pathogens or in some others it causes pathogenesis and mortality [37][38][39]. In B. dorsalis, this bacterium has been reported to increase fecundity but lower the longevity of adult ies [26].…”