title: Pteromalus puparum venom impairs host cellular immune responses by decreasing expression of its scavenger receptor gene.
abstract: Insect host/parasitoid interactions are co-evolved systems in which host defenses are balanced by parasitoid mechanisms to disable or hide from host immune effectors. Although there is a rich literature on these systems, parasitoid immune-disabling mechanisms have not been fully elucidated. Here we report on a newly discovered immune-disabling mechanism in the Pieris rapae/Pteromalus puparum host/parasitoid system. Because venom injections and parasitization suppresses host phagocytosis, we turned attention to the P. rapae scavenger receptor (Pr-SR), posing the hypothesis that P. puparum venom suppresses expression of the host Pr-SR gene. To test our hypothesis, we cloned a full-length cDNA of the Pr-SR. Multiple sequences alignment showed the deduced amino acid sequence of Pr-SR is similar to scavenger receptors of other lepidopterans. Bacterial and bead injections induced Pr-SR mRNA and protein expression, which peaked at 4h post-bead injection. Venom injection inhibited Pr-SR expression. Pr-SR was specifically expressed in granulocytes compared to plasmatocytes. We localized the Pr-SR protein in cytoplasm and cellular membrane, with no evidence of secretion into host plasma. Double-strand RNA designed to Pr-SR mRNA silenced expression of Pr-SR and significantly impaired host phagocytosis and encapsulation reactions. Venom injections similarly silenced Pr-SR expression during the first 8h post-treatment, after which the silencing effects gradually abated. We infer from these findings that one mechanism of impairing P. rapae hemocytic immune reactions is by silencing expression of Pr-SR.
authors.affiliation: State Key Laboratory of Rice Biology & Key Laboratory of Molecular Biology of Crop Pathogens and Insects of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310029, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Fang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Yangkeng
authors.initials: Y
authors.lastname: Zhu
authors.forename: David W
authors.initials: DW
authors.lastname: Stanley
authors.forename: Xuexin
authors.initials: X
authors.lastname: Chen
authors.forename: Cui
authors.initials: C
authors.lastname: Hu
authors.forename: Gongyin
authors.initials: G
authors.lastname: Ye
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006434:Hemocytes / Q000187:drug effects / Q000378:metabolism; D006790:Host-Parasite Interactions / Q000276:immunology*; D007106:Immune Sera; D007111:Immunity, Cellular / Q000187:drug effects*; D008969:Molecular Sequence Data; D009036:Moths / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000469:parasitology*; D010587:Phagocytosis / Q000187:drug effects; D011679:Pupa / Q000187:drug effects / Q000276:immunology; D034622:RNA Interference; D051116:Receptors, Scavenger / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014862:Wasp Venoms / Q000494:pharmacology*; D014863:Wasps
chemical_list: D007106:Immune Sera; D051116:Receptors, Scavenger; D011994:Recombinant Proteins; D014862:Wasp Venoms