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Transcriptome analysis of Bombyx mori larval midgut during persistent and pathogenic cytoplasmic polyhedrosis virus infection.

Kolliopoulou A, Van Nieuwerburgh F, Stravopodis DJ, Deforce D, Swevers L, Smagghe G - PLoS ONE (2015)

Bottom Line: Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection.Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae.Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism.

View Article: PubMed Central - PubMed

Affiliation: Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Aghia Paraskevi, Athens, Greece.

ABSTRACT
Many insects can be persistently infected with viruses but do not show any obvious adverse effects with respect to physiology, development or reproduction. Here, Bombyx mori strain Daizo, persistently infected with cytoplasmic polyhedrosis virus (BmCPV), was used to study the host's transcriptional response after pathogenic infection with the same virus in midgut tissue of larvae persistently and pathogenically infected as 2nd and 4th instars. Next generation sequencing revealed that from 13,769 expressed genes, 167 were upregulated and 141 downregulated in both larval instars following pathogenic infection. Several genes that could possibly be involved in B. mori immune response against BmCPV or that may be induced by the virus in order to increase infectivity were identified, whereas classification of differentially expressed transcripts (confirmed by qRT-PCR) resulted in gene categories related to physical barriers, immune responses, proteolytic/metabolic enzymes, heat-shock proteins, hormonal signaling and uncharacterized proteins. Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection. To investigate the possible host's RNAi response against BmCPV challenge, the differential expression of RNAi-related genes and the accumulation of viral small RNAs (vsRNAs) were studied. During pathogenic infection, siRNA-like traces like the 2-fold up-regulation of the core RNAi genes Ago-2 and Dcr-2 as well as a peak of 20 nt small RNAs were observed. Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae. Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism.

No MeSH data available.


Related in: MedlinePlus

Expression levels of RNAi-related genes from pathogenically infected midguts as analyzed by deep sequencing and validated by qRT-PCR.Indicated is the fold change in expression of selected genes between persistent and pathogenic infection as obtained by qRT-PCR on 2nd instar samples (qPCR-2) or by deep sequencing on both 2nd and 4th instar samples (DS-2 and DS-4, respectively). Please note that fold changes are expressed as log2 values (a 2-fold up- or down-regulation corresponds to a log2 value of 1 or -1, respectively). See Table 5 and [64] for further explanation on gene identity and function.
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pone.0121447.g006: Expression levels of RNAi-related genes from pathogenically infected midguts as analyzed by deep sequencing and validated by qRT-PCR.Indicated is the fold change in expression of selected genes between persistent and pathogenic infection as obtained by qRT-PCR on 2nd instar samples (qPCR-2) or by deep sequencing on both 2nd and 4th instar samples (DS-2 and DS-4, respectively). Please note that fold changes are expressed as log2 values (a 2-fold up- or down-regulation corresponds to a log2 value of 1 or -1, respectively). See Table 5 and [64] for further explanation on gene identity and function.

Mentions: Following application of the BLASTP algorithm in the NCBI database on the B. mori genome, as well as use of the BLAST tool in the www.silkdb.org database, homologs (annotated or not) of several RNAi-related genes originally implicated in the RNAi process in other organisms were identified in the silkworm’s genome (for a discussion of different categories of RNAi-related genes, see [64]). Deep sequencing data were then analyzed to pinpoint alterations of the expression of RNAi-related genes following a pathogenic infection with BmCPV. The expression of several core RNAi genes and additional RNAi-related factors (Table 4) was further confirmed by qRT-PCR in 2nd instar midgut cDNA samples (Fig. 6; S6 Fig.).


Transcriptome analysis of Bombyx mori larval midgut during persistent and pathogenic cytoplasmic polyhedrosis virus infection.

Kolliopoulou A, Van Nieuwerburgh F, Stravopodis DJ, Deforce D, Swevers L, Smagghe G - PLoS ONE (2015)

Expression levels of RNAi-related genes from pathogenically infected midguts as analyzed by deep sequencing and validated by qRT-PCR.Indicated is the fold change in expression of selected genes between persistent and pathogenic infection as obtained by qRT-PCR on 2nd instar samples (qPCR-2) or by deep sequencing on both 2nd and 4th instar samples (DS-2 and DS-4, respectively). Please note that fold changes are expressed as log2 values (a 2-fold up- or down-regulation corresponds to a log2 value of 1 or -1, respectively). See Table 5 and [64] for further explanation on gene identity and function.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376736&req=5

pone.0121447.g006: Expression levels of RNAi-related genes from pathogenically infected midguts as analyzed by deep sequencing and validated by qRT-PCR.Indicated is the fold change in expression of selected genes between persistent and pathogenic infection as obtained by qRT-PCR on 2nd instar samples (qPCR-2) or by deep sequencing on both 2nd and 4th instar samples (DS-2 and DS-4, respectively). Please note that fold changes are expressed as log2 values (a 2-fold up- or down-regulation corresponds to a log2 value of 1 or -1, respectively). See Table 5 and [64] for further explanation on gene identity and function.
Mentions: Following application of the BLASTP algorithm in the NCBI database on the B. mori genome, as well as use of the BLAST tool in the www.silkdb.org database, homologs (annotated or not) of several RNAi-related genes originally implicated in the RNAi process in other organisms were identified in the silkworm’s genome (for a discussion of different categories of RNAi-related genes, see [64]). Deep sequencing data were then analyzed to pinpoint alterations of the expression of RNAi-related genes following a pathogenic infection with BmCPV. The expression of several core RNAi genes and additional RNAi-related factors (Table 4) was further confirmed by qRT-PCR in 2nd instar midgut cDNA samples (Fig. 6; S6 Fig.).

Bottom Line: Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection.Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae.Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism.

View Article: PubMed Central - PubMed

Affiliation: Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Aghia Paraskevi, Athens, Greece.

ABSTRACT
Many insects can be persistently infected with viruses but do not show any obvious adverse effects with respect to physiology, development or reproduction. Here, Bombyx mori strain Daizo, persistently infected with cytoplasmic polyhedrosis virus (BmCPV), was used to study the host's transcriptional response after pathogenic infection with the same virus in midgut tissue of larvae persistently and pathogenically infected as 2nd and 4th instars. Next generation sequencing revealed that from 13,769 expressed genes, 167 were upregulated and 141 downregulated in both larval instars following pathogenic infection. Several genes that could possibly be involved in B. mori immune response against BmCPV or that may be induced by the virus in order to increase infectivity were identified, whereas classification of differentially expressed transcripts (confirmed by qRT-PCR) resulted in gene categories related to physical barriers, immune responses, proteolytic/metabolic enzymes, heat-shock proteins, hormonal signaling and uncharacterized proteins. Comparison of our data with the available literature (pathogenic infection of persistently vs. non-persistently infected larvae) unveiled various similarities of response in both cases, which suggests that pre-existing persistent infection does not affect in a major way the transcriptome response against pathogenic infection. To investigate the possible host's RNAi response against BmCPV challenge, the differential expression of RNAi-related genes and the accumulation of viral small RNAs (vsRNAs) were studied. During pathogenic infection, siRNA-like traces like the 2-fold up-regulation of the core RNAi genes Ago-2 and Dcr-2 as well as a peak of 20 nt small RNAs were observed. Interestingly, vsRNAs of the same size were detected at lower rates in persistently infected larvae. Collectively, our data provide an initial assessment of the relative significance of persistent infection of silkworm larvae on the host response following pathogenic infection with CPV, while they also highlight the relative importance of RNAi as an antiviral mechanism.

No MeSH data available.


Related in: MedlinePlus