Transcriptome Sequencing of the Spleen Reveals Antiviral Response Genes in Chickens Infected with CAstV

Astrovirus infections pose a significant problem in the poultry industry, leading to multiple adverse effects such as a decreased egg production, breeding disorders, poor weight gain, and even increased mortality. The commonly observed chicken astrovirus (CAstV) was recently reported to be responsible for the “white chicks syndrome” associated with an increased embryo/chick mortality. CAstV-mediated pathogenesis in chickens occurs due to complex interactions between the infectious pathogen and the immune system. Many aspects of CAstV–chicken interactions remain unclear, and there is no information available regarding possible changes in gene expression in the chicken spleen in response to CAstV infection. We aim to investigate changes in gene expression triggered by CAstV infection. Ten 21-day-old SPF White Leghorn chickens were divided into two groups of five birds each. One group was inoculated with CAstV, and the other used as the negative control. At 4 days post infection, spleen samples were collected and immediately frozen at −70 °C for RNA isolation. We analyzed the isolated RNA, using RNA-seq to generate transcriptional profiles of the chickens’ spleens and identify differentially expressed genes (DEGs). The RNA-seq findings were verified by quantitative reverse-transcription PCR (qRT-PCR). A total of 31,959 genes was identified in response to CAstV infection. Eventually, 45 DEGs (p-value < 0.05; log2 fold change > 1) were recognized in the spleen after CAstV infection (26 upregulated DEGs and 19 downregulated DEGs). qRT-PCR performed on four genes (IFIT5, OASL, RASD1, and DDX60) confirmed the RNA-seq results. The most differentially expressed genes encode putative IFN-induced CAstV restriction factors. Most DEGs were associated with the RIG-I-like signaling pathway or more generally with an innate antiviral response (upregulated: BLEC3, CMPK2, IFIT5, OASL, DDX60, and IFI6; downregulated: SPIK5, SELENOP, HSPA2, TMEM158, RASD1, and YWHAB). The study provides a global analysis of host transcriptional changes that occur during CAstV infection in vivo and proves that, in the spleen, CAstV infection in chickens predominantly affects the cell cycle and immune signaling

In ovo administration of CpG ODN induces expression of immune response genes in neonatal chicken spleen

Introduction: Due to their immunostimulatory properties TLR ligands are used prophylactically to protect against a variety of viral and bacterial pathogens in mammals. Knowledge of the molecular and functional aspects of TLRs is essential for a better understanding of the immune system and resistance to diseases in birds. For that reason, this study attempted to determine the impact of TLR21 stimulation by its synthetic ligand (CpG ODN, class B) on the chicken immune system

Molecular Epidemiology of Turkey Coronaviruses in Poland

The only knowledge of the molecular structure of European turkey coronaviruses (TCoVs) comes from France. These viruses have a quite distinct S gene from North American isolates. The aim of the study was to estimate the prevalence of TCoV strains in a Polish turkey farm during a twelve-year period, between 2008 and 2019, and to characterize their full-length S gene. Out of the 648 flocks tested, 65 (10.0%, 95% CI: 7.9–12.6) were positive for TCoV and 16 of them were molecularly characterized. Phylogenetic analysis showed that these strains belonged to two clusters, one formed by the early isolates identified at the beginning of the TCoV monitoring (from 2009 to 2010), and the other, which was formed by more recent strains from 2014 to 2019. Our analysis of the changes observed in the deduced amino acids of the S1 protein suggests the existence of three variable regions. Moreover, although the selection pressure analysis showed that the TCoV strains were evolving under negative selection, some sites of the S1 subunit were positively selected, and most of them were located within the proposed variable regions. Our sequence analysis also showed one TCoV strain had recombined with another one in the S1 gene. The presented investigation on the molecular feature of the S gene of TCoVs circulating in the turkey population in Poland contributes interesting data to the current state of knowledge

Transcriptome Sequencing of the Spleen Reveals Antiviral Response Genes in Chickens Infected with CAstV

Astrovirus infections pose a significant problem in the poultry industry, leading to multiple adverse effects such as a decreased egg production, breeding disorders, poor weight gain, and even increased mortality. The commonly observed chicken astrovirus (CAstV) was recently reported to be responsible for the “white chicks syndrome” associated with an increased embryo/chick mortality. CAstV-mediated pathogenesis in chickens occurs due to complex interactions between the infectious pathogen and the immune system. Many aspects of CAstV–chicken interactions remain unclear, and there is no information available regarding possible changes in gene expression in the chicken spleen in response to CAstV infection. We aim to investigate changes in gene expression triggered by CAstV infection. Ten 21-day-old SPF White Leghorn chickens were divided into two groups of five birds each. One group was inoculated with CAstV, and the other used as the negative control. At 4 days post infection, spleen samples were collected and immediately frozen at −70 °C for RNA isolation. We analyzed the isolated RNA, using RNA-seq to generate transcriptional profiles of the chickens’ spleens and identify differentially expressed genes (DEGs). The RNA-seq findings were verified by quantitative reverse-transcription PCR (qRT-PCR). A total of 31,959 genes was identified in response to CAstV infection. Eventually, 45 DEGs (p-value 2 fold change > 1) were recognized in the spleen after CAstV infection (26 upregulated DEGs and 19 downregulated DEGs). qRT-PCR performed on four genes (IFIT5, OASL, RASD1, and DDX60) confirmed the RNA-seq results. The most differentially expressed genes encode putative IFN-induced CAstV restriction factors. Most DEGs were associated with the RIG-I-like signaling pathway or more generally with an innate antiviral response (upregulated: BLEC3, CMPK2, IFIT5, OASL, DDX60, and IFI6; downregulated: SPIK5, SELENOP, HSPA2, TMEM158, RASD1, and YWHAB). The study provides a global analysis of host transcriptional changes that occur during CAstV infection in vivo and proves that, in the spleen, CAstV infection in chickens predominantly affects the cell cycle and immune signaling