RESUMO
To establish successful infections, endoparasitoid wasps must develop strategies to evade immune responses of the host. Here, we identified and characterized a teratocytes-expressed gene encoding a trypsin inhibitor-like protein containing a cysteine-rich domain from Cotesia vestalis, CvT-TIL. CvT-TIL had a high expression level during the later developmental stage of teratocytes and was secreted into host hemolymph. Further experiments showed CvT-TIL strongly suppressed the prophenoloxidase activation of host hemolymph in a dose-dependent manner by interacting with PxPAP3 of PO cascade. Our results not only provide evidence for an inhibition between CvT-TIL gene and the host's melanization activity, but also expand our knowledge about the mechanisms by which parasitoids regulate humoral immunity of the host.
Assuntos
Catecol Oxidase/genética , Precursores Enzimáticos/genética , Hemolinfa/metabolismo , Interações Hospedeiro-Parasita , Proteínas de Insetos/genética , Larva/fisiologia , Inibidores da Tripsina/metabolismo , Vespas/fisiologia , Sequência de Aminoácidos , Animais , Catecol Oxidase/metabolismo , Precursores Enzimáticos/metabolismo , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Larva/genética , Larva/crescimento & desenvolvimento , Larva/parasitologia , Alinhamento de Sequência , Ativação Transcricional , Inibidores da Tripsina/química , Vespas/genéticaRESUMO
Parasitic wasps produce several factors including venom, polydnaviruses (PDVs) and specialized wasp cells named teratocytes that benefit the survival of offspring by altering the physiology of hosts. However, the underlying molecular mechanisms for the alterations remain unclear. Here we find that the teratocytes of Cotesia vestalis, an endoparasitoid of the diamondback moth Plutella xylostella, and its associated bracovirus (CvBV) can produce miRNAs and deliver the products into the host via different ways. Certain miRNAs in the parasitized host are mainly produced by teratocytes, while the expression level of miRNAs encoded by CvBV can be 100-fold greater in parasitized hosts than non-parasitized ones. We further show that one teratocyte-produced miRNA (Cve-miR-281-3p) and one CvBV-produced miRNA (Cve-miR-novel22-5p-1) arrest host growth by modulating expression of the host ecdysone receptor (EcR). Altogether, our results show the first evidence of cross-species regulation by miRNAs in animal parasitism and their possible function in the alteration of host physiology during parasitism.
Assuntos
Interações Hospedeiro-Parasita/genética , MicroRNAs/fisiologia , Mariposas/crescimento & desenvolvimento , Parasitos/genética , Polydnaviridae/genética , Vespas/genética , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento/genética , Larva/genética , Larva/virologia , Mariposas/parasitologia , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Vespas/virologiaRESUMO
Some endoparasitoid wasps lay eggs that produce cells called teratocytes. In this study, we sequenced and analyzed the transcriptome of teratocytes from the solitary endoparasitoid Cotesia vestalis (Braconidae), which parasitizes larval stage Plutella xylostella (Plutellidae). Results identified many teratocyte transcripts with potential functions in affecting host immune defenses, growth or metabolism. Characterization of teratocyte-secreted venom-like protein 8 (TSVP-8) indicated it inhibits melanization of host hemolymph in vitro, while two predicted anti-microbial peptides (CvT-def 1 and 3) inhibited the growth of bacteria. Results also showed the parasitized hosts lacking teratocytes experienced higher mortality after immune challenge by pathogens than hosts with teratocytes. Taken together, these findings indicate that C. vestalis teratocytes secrete products that alter host immune functions while also producing anti-microbial peptides with functions that help protect the host from infection by other organisms.
