MicroRNAs from Snellenius manilae bracovirus regulate innate and cellular immune responses of its host Spodoptera litura

Abstract

To avoid inducing immune and physiological responses in insect hosts, parasitoid wasps have developed several mechanisms to inhibit them during parasitism, including the production of venom, specialized wasp cells, and symbioses with polydnaviruses (PDVs). These mechanisms alter the host physiology to give the wasp offspring a greater chance of survival. However, the molecular mechanisms for most of these alterations remain unclear. In the present study, we applied next-generation sequencing analysis and identified several miRNAs that were encoded in the genome of Snellenius manilae bracovirus (SmBV), and expressed in the host larvae, Spodoptera litura, during parasitism. Among these miRNAs, SmBV-miR-199b-5p and SmBV-miR-2989 were found to target domeless and toll-7 in the host, which are involved in the host innate immune responses. Microinjecting the inhibitors of these two miRNAs into parasitized S. litura larvae not only severely decreased the pupation rate of Snellenius manilae, but also restored the phagocytosis and encapsulation activity of the hemocytes. The results demonstrate that these two SmBV-encoded miRNAs play an important role in suppressing the immune responses of parasitized hosts. Overall, our study uncovers the functions of two SmBV-encoded miRNAs in regulating the host innate immune responses upon wasp parasitism.

Advances in the Immune Regulatory Role of Non-Coding RNAs (miRNAs and lncRNAs) in Insect-Pathogen Interactions

“…Few studies investigated the link between ncRNAs and insect accessory defense mechanisms. miRNAs of Snellenius manilae bracovirus (SmBV-miR-199b5p and SmBV-miR-2989) were found to regulate innate ( domeless and toll-7 ) and cellular (encapsulation and phagocytosis activity of the hemocytes) immune responses of its host Spodoptera litura ( 181 ). Plutella xylostella miR-8 is downregulated following parasitization by Diadegma semiclausum , leading to significant declines in Serpin 27 transcript levels ( 182 ).…”

Enhancing the insecticidal potential of a baculovirus by overexpressing the mammalian β‐galactosyl binding protein galectin‐1

“…The content was poured into a container and allowed to harden and was kept at 4 °C until use. Tobacco cutworms were kept in round and transparent plastic boxes [8 cm (length) × 5.5 cm (height)] at 26 ± 1 °C with an alternating light/dark cycle of 12 h:12 h. Feed was refreshed daily 28 …”

“…Feed was refreshed daily. (Tang et al, 2021) Measurement of survival rate, appetite and body length Second-instar S. litura larvae were divided into 4 groups, control, wild-type baculovirus (wt AcMNPV), recombinant vABpRpGal1 (vABpRpGal1) group and commercially available biological insecticides (Bacillus thuringiensis (0.3 kilograms per hectare)). Larvae in wt AcMNPV and vABpRpGal1 groups were fed with 1 x 10 6 pfu virus/larva.…”

“…Tobacco cutworms were kept in round and transparent plastic boxes [8 cm (length) × 5.5 cm (height)] at 26 ± 1 °C with an alternating light/dark cycle of 12 h:12 h. Feed was refreshed daily. 28 2.5 Measurement of survival rate, appetite, and body length Second-instar S. litura larvae were divided into four groups, the control virus (vABpR, −Gal-1), recombinant virus (vABpRpGal1, +Gal-1), and commercially available biological insecticide [Bacillus thuringiensis (0.3 kg/ha)] groups. Larvae in vABpR (−Gal-1) and vABpRpGal1 (+Gal-1) groups were fed 1 × 10 6 pfu virus/larva.…”

The microRNAs in the Antennae of <em>Apolygus lucorum</em> (Hemiptera: Miridae): Expression Properties and Targets Prediction

“…Insect miRNAs contribute in numerous biological functions including metamorphosis and molting, sex determination, reproduction (ovarian development and oogenesis), immunity, wing polyphenism and development, pesticide resistance, chemical communication (olfaction and gustation) and so on. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. In D. melanogaster, miR-8 regulates the transcript of gene associated with the biosynthesis of juvenile hormone (JH) and alters the cell growth in the corpus allatum (CA), causing pupal mortality [34].…”