Apoptotic effects of hydrogen peroxide and vitamin C on chicken embryonic fibroblasts: redox state and programmed cell death

Integration of ALV into CTDSPL and CTDSPL2 genes in B-cell lymphomas promotes cell immortalization, migration and survival

Avian leukosis virus induces tumors in chickens by integrating into the genome and altering expression of nearby genes. Thus, ALV can be used as an insertional mutagenesis tool to identify novel genes involved in tumorigenesis. Deep sequencing analysis of viral integration sites has identified CTDSPL and CTDSPL2 as common integration sites in ALV-induced B-cell lymphomas, suggesting a potential role in driving oncogenesis. We show that in tumors with integrations in these genes, the viral promoter is driving the expression of a truncated fusion transcript. Overexpression in cultured chick embryo fibroblasts reveals that CTDSPL and CTDSPL2 have oncogenic properties, including promoting cell migration. We also show that CTDSPL2 has a previously uncharacterized role in protecting cells from apoptosis induced by oxidative stress. Further, the truncated viral fusion transcripts of both CTDSPL and CTDSPL2 promote immortalization in primary cell culture.

Enhanced replication of avian-origin H3N2 canine influenza virus in eggs, cell cultures and mice by a two-amino acid insertion in neuraminidase stalk

Canine influenza virus (CIV) is a newly identified, highly contagious respiratory pathogen in dogs. Recent studies indicate that avian-origin H3N2 CIV are circulating in Chinese dogs. To investigate the effects of a two-amino acid (2-aa) insertion naturally occurring at the distal end of the neuraminidase (NA) stalk found in Chinese isolates since 2010 on virus replication and virulence, we rescued the CIV strain, A/canine/Jiangsu/06/2011(H3N2) and its NA mutant without the 2-aa insertion using reverse genetics. The NA stalk length affected virus growth in cell culture. Compared to the short stalk strain (without 2-aa insertion), the long stalk strain (with 2-aa insertion) exhibited higher peak titers and greater yields in Madin-Darby canine kidney (MDCK) cells, chicken embryo fibroblasts and canine bronchiolar epithelial cells, as well as much larger plaques in MDCK cell monolayers. Furthermore, mice inoculated with the long stalk strain showed more severe pathologic damage in lung and higher proportion of detectable viral RNA in tissues. The long stalk strain induced local IFN-γ production with faster kinetics and higher levels in mice. However, in chickens, the two viral strains showed no significant difference with nearly the same proportion of detectable viral RNA loads in tissues. These observations suggest that the 2-aa insertion in the NA stalk acquired by avian-origin H3N2 CIV helps to enhance viral replication and is likely a result of adaptive evolution in canine hosts.

Selection of reference genes for quantitative real-time PCR analysis in chicken embryo fibroblasts infected with avian leukosis virus subgroup J

Background

The selection of stably expressed reference genes is a prerequisite when evaluating gene expression, via real-time PCR, in cells in response to viral infections. The objective of our study was to identify suitable reference genes for mRNA expression analysis in chicken embryonic fibroblasts (CEF) after infection with avian leukosis virus subgroup J (ALV-J).

Findings

The expression levels of 11 potential reference genes in CEF infected with ALV-J were determined by real-time PCR. The expression stability of these genes were analyzed and ranked using the geNorm tool. Analysis indicated that the genes RPL30 (ribosomal protein L30) and SDHA (succinate dehydrogenase complex, subunit A) were the most stably expressed genes in the ALV-J infected CEF.

Conclusions

The RPL30 and SDHA were deemed suitable for use as reference genes for real-time PCR analysis of mRNA gene expression during ALV-J infection, whereas commonly used ACTB and GAPDH are unsuitable to be reference genes.