Screening of Bombyx mori brain proteins interacting with protein tyrosine phosphatase of BmNPV.

In this study, glutathione-S-transferase pull-down combined with mass spectrometry techniques were used to identify the candidate proteins interacting with protein tyrosine phosphatase of the Bombyx Mori nucleopolyhedrovirus in the B. mori (BmNPV-PTP) brain. A total of 36 proteins were identified from BmNPV-PTP coprecipitate samples by searching the NCBI_Bombyx Mori database with the original mass spectrum data. Among those proteins, the interaction between BmNPV-PTP and B. mori cyclophilin A may accelerate the apoptosis of certain nerve cells involved in regulating behavior, and thus may be an inducer of enhanced locomotor activity (ELA). After the BmNPV invasion, BmNPV-PTP binding to peripheral-type benzodiazepine receptors may initiate a series of abnormal cascades of the nervous system, which results in abnormal hyperactive behavior in B. mori. Besides this, vacuolar ATP synthase catalytic subunit A, annexin, and several enzymes for energy conversion were identified, which may play a role in enhancing viral entry and infectivity and provide energy for enhancing the locomotor activity of B. mori. In general, the results of this study will facilitate the understanding of the molecular mechanisms underlying the ELA of B. mori larva induced by BmNPV.

Truncated reactive center loop decrease the inhibitory activity of Antheraea pernyi serine protease inhibitor 6.

Here, we assessed the effect of a systematic change in reactive center loop (RCL) length, N-terminal to the reactive center, on the inhibitory activity of the recombinant Apserpin-6. The domain prediction results indicated that the RCL is located between the amino acid numbered 359-379 at the C-terminal of Apserpin-6. The N-terminal variable region for amino acid positions P7-P1 of the RCL of Apserpin-6 was truncated or extended by residue deletion or insertion using site-directed mutagenesis. The recombinant Apserpin-6 with one or two residues insertion in RCL had no effect on prophenoloxidase (proPO) activity, whereas deletion of one or two residues in RCL lowered the efficiency of inhibition of Apserpin-6. The results of this study will facilitate the understanding of inhibition mechanism of RCL on proPO activity.

Uncovering the cellular and humoral immune responses of Antheraea pernyi hemolymph to Antheraea pernyi nucleopolyhedrovirus infection by transcriptome analysis.

Insects have evolved efficient innate immune systems to defend themselves against the invasion of pathogens and parasites. We infected the lepidopteran Antheraea pernyi with Antheraea pernyi nucleopolyhedrovirus (ApNPV) and studied the host's transcriptional response to unravel the cellular and humoral immune responses of A. pernyi larval hemolymph to ApNPV. Comparison of gene expression levels revealed that a total of 3191 genes were differentially expressed, including 1107 up-regulated and 2084 down-regulated genes in ApNPV-infected hemolymph. Of these, 1416 and 982 differentially expressed genes (DEGs) were enriched in 3253 Gene Ontology terms and 258 KEGG pathways, respectively. DEGs involved in immunity related pathways were selected for further analysis. We screened 184 and 63 DEGs involved in cellular and humoral immune-related pathways, respectively, via KEGG analysis. Among the cellular immune-related pathways, autophagy, endocytosis, and lysosome were activated based on the expression profiles of several key regulatory genes, such as the up-regulation of Atg3 and LPS-induced TN factor, and the down-regulation of PIK3R4, HSC70 and V-ATPase. We concluded that phagosome, apoptosis, and ubiquitin-mediated proteolysis were suppressed by ApNPV as a result of down-regulation of most related DEGs. The majority of the DEGs enriched in Toll, Jak-STAT, MAPK, NF-κB and Insulin signaling pathways, complement and coagulation cascades, and melanogenesis were down-regulated, demonstrating that ApNPV infection greatly inhibited humoral immunity in the hemolymph of A. pernyi larvae. Our findings may serve as a basis for further research on the antiviral molecular mechanisms of A. pernyi.

Transcriptome sequencing to unravel the molecular mechanisms underlying the cuticle liquefaction of Antheraea pernyi following Antheraea pernyi nucleopolyhedrovirus challenge.

Baculovirus causes liquefaction of insect cuticle to enhance the dissemination of progeny virions away from the host cadavers for increasing viral transmission rates. Antheraea pernyi nucleopolyhedrovirus (ApNPV) infects A. pernyi larvae with circular pus blotches formed in cuticle in the early stage of liquefaction. To investigate the formation mechanism of those pus blotches, the transcriptome profile changes of the cuticles between ApNPV-infected and non-infected A. pernyi larvae were analyzed using RNA-Seq. The transcriptome was de novo assembled using the Trinity platform. Comparison of gene expression levels revealed that a total of 2990 and 4427 unigenes were up- and down-regulated respectively in ApNPV-infected cuticle, of which 2620 and 1903 differentially expressed genes (DEGs) could be enriched in different GO terms and KEGG pathways. In this study, we focused on chitin metabolism related DEGs, and screened 10 genes involved in chitin synthesis and degradation with down-regulated trends, indicating that the chitin metabolism pathway was inhibited by ApNPV infection, which may promote liquefaction of A. pernyi cuticle. Besides, we also identified a large number of DEGs involved in immune related pathways via KEGG analysis, indicating that intense immune responses occurred in A. pernyi cuticle. Our research findings will serve as a basis for further researching the molecular mechanisms underlying cuticle liquefaction of A. pernyi induced by ApNPV infection.