Altering of host larval (Spodoptera exigua) calcineurin activity in response to ascovirus infection

Abstract

BACKGROUND Calcineurin (CaN) is involved in numerous cellular processes and Ca2+‐dependent signal transduction pathways. According to our previous transcriptome studies, thousands of host larval (Spodoptera exigua) transcripts were downregulated after the infection of Heliothis virescent ascovirus 3h (HvAV‐3h), while the Spodoptera exigua calcineurin genes (SeCaNs) were significantly upregulated. To understand the regulation of SeCaNs in S. exigua larvae during the infection of HvAV‐3h, the functions of CaN subunit A (SeCaN‐SubA) and CaN binding protein (SeCaN‐BP) were analysed. RESULTS The in vitro assays indicated that the bacterial expressed SeCaN‐SubA is an acid phosphatase, but no phosphatase activity was detected with the purified SeCaN‐BP. The transcription level of SeCaN‐SubA was upregulated after HvAV‐3h infection and the CaN activity was significantly increased after HvAV‐3h infection in S. exigua larvae. Interestingly, the SeCaN‐BP transcripts were only detectable in the HvAV‐3h infected larvae. Further immunoblotting results consistently agree with those obtained by qPCR, indicating that the infection of HvAV‐3h causes the upregulated expression of SeCaN‐SubA and the appearance of SeCaN‐BP. An interaction between the cleaved SeCaN‐SubA and SeCaN‐BP was detected by co‐immunoprecipitation assays, and the expression of SeCaN‐BP in Spodoptera frugiperda‐9 (Sf9) cells can help to increase the CaN activity of SeCaN‐SubA. Further investigations with CaN inhibitors suggested that HvAV‐3h. Further investigations with CaN inhibitors suggested that the inhibition on host larval CaN activity can also inhibit the viral replication of HvAV‐3h. CONCLUSION The increase in CaN activity caused by HvAV‐3h infection might be due to the upregulation of SeCaN‐SubA and the induced expression of SeCaN‐BP, and increased CaN activity is essential for ascoviral replication. © 2019 Society of Chemical Industry

Preparation and Application Analysis of a Polyclonal Antibody as Reference Protein in Helicoverpa armigera (Lepidoptera: Noctuidae)

“…At present, the most commonly used research method for gene detection is qRT-PCR, which detects the expression level of the target gene quickly and with great sensitivity (Dong et al 2022; Liu et al 2022a; Yang et al 2021). The most commonly used method for quantitative and qualitative analysis of functional proteins is western blot (He et al 2022; Wan et al 2022; Yu et al 2020b). There are many reference genes for qRT-PCR in studies of H. armigera , e.g., GAPDH was evaluated as the most stable reference gene in larvae subjected to mechanical injury or nuclear polyhedrosis virus infection (Shakeel et al 2015); tubulin was recognized as the stable gene across different developmental stages (Chandra et al 2014).…”

Melanization induced by Heliothis virescens ascovirus 3h promotes viral replication

“…According to a previous report, ascoviruses use host cellular apoptotic processes to form their vesicles (Bideshi et al ., 2005, Federici et al ., 2009). Our previous study demonstrated that the replication of HvAV‐3h requires high CaN activity (Yu et al ., 2020a). Abnormality of CaN will lead to dysfunction of its participation in downstream pathways, including apoptosis (Quadroni et al ., 1998; Olofsson et al ., 2008).…”

“…Infection with HvAV‐3h can significantly inhibit the growth and development of S. exigua , Spodoptera litura and H. armigera larvae (Li et al ., 2013; Hu et al ., 2016; He et al ., 2020). In addition, a recent study has shown that calcineurin (CaN), an enzyme involved in some immune responses of insects, increases its activity after HvAV‐3h infection, which is beneficial for HvAV‐3h replication (Yu et al ., 2020a). These results indicated that how HvAV‐3h overcomes or coexists with the humoral immunity of host larvae is closely related to its pathogenesis.…”

Novel strategies for the biocontrol of noctuid pests (Lepidoptera) based on improving ascovirus infectivity using Bacillus thuringiensis

“…Ascovirus infections show tissue specificity, and according to histopathological observations the guts of S. frugiperda , S. ornithogalli , S. exigua , S. eridania , H. virescens , H. zea , Autographa precationis , and Feltia subterranea are not infected by ascovirus (Hamm et al ., 1998). However, during our previous study on host larval response to HvAV‐3h infection, we observed expression of the major capsid protein (MCP) encoded by HvAV‐3h in the midgut of 3rd‐instar S. exigua larvae (Yu et al ., 2020). MCP and several other virally encoded structural proteins and enzymes are used to identify the viral evolution among different viral species (Cheng et al ., 2003; Zhao & Cui, 2003; Salem et al ., 2008).…”