Gene profiling analysis of ALVAC infected human monocyte derived dendritic cells

Abstract

The recombinant canarypox virus ALVAC is being extensively studied as vaccine vector for the development of new vaccine strategies against chronic infectious diseases and cancer. However, the mechanisms by which ALVAC initiates the immune response have not been completely elucidated. In order to determine the type of innate immunity triggered by ALVAC, we characterized the gene expression profile of human monocyte derived dendritic cells (MDDCs) upon ALVAC infection. These cells are permissive to poxvirus infection and play a key role in the initiation of immune responses. The majority of the genes that were up-regulated by ALVAC belong to the type I interferon signaling pathway including IRF7, STAT1, RIG-1, and MDA-5. Genes involved in the NF-kappaB pathway were not up-regulated. The gene encoding for the chemokine CXCL10, a direct target of the transcription factor IRF3 was among those up-regulated and DC secretion of CXCL10 following exposure to ALVAC was confirmed by ELISA. Many downstream type I interferon activated genes with anti-viral activity (PKR, Mx, ISG15 and OAS among others) were also up-regulated in response to ALVAC. Among these, ISG15 expression in its unconjugated form by Western blot analysis was demonstrated. In view of these results we propose that ALVAC induces type I interferon anti-viral innate immunity via a cytosolic pattern-recognition-receptor (PRR) sensing double-stranded DNA, through activation of IRF3 and IRF7. These findings may aid in the design of more effective ALVAC-vectored vaccines.

Priming and Activation of Inflammasome by Canarypox Virus Vector ALVAC via the cGAS/IFI16–STING–Type I IFN Pathway and AIM2 Sensor

“…2A). This finding is consistent with several previous studies reporting that human Ad5 virus or recombinant Ad5 vector alone is generally less innate immune stimulatory and induces very little activation of DCs (30); in contrast, ALVAC vector can more potently stimulate activation of APCs, leading to expression of antiviral gene expression (15) and production of inflammatory cytokines (16). Mechanisms for limited stimulatory activity of Ad5 vector on DCs are not fully known but may be related to the fact that Ad5 virus is a human pathogen and may evolve immune escape mechanisms from innate recognition by host defense responses.…”

“…In the context of virally vectored vaccination, such innate recognition of vector-associated PAMPs by host APCs occurs as well, but has not been well explored. Prior studies have demonstrated that ALVAC could efficiently infect human dendritic cells (DCs) (14) and induced strong antiviral response (15, 16). Similarly, human Ad5 vectors were also shown to be able to infect a range of cell types including APCs (17).…”

Antiretroviral Therapy Down-Regulates Innate Antiviral Response Genes in Patients With AIDS in Sub-Saharan Africa

“…Additional PRR genes involved in innate responses to dsRNA that were down-regulated included DDX58 (also known as RIG-1 ) and thereafter IRF7 . 5, 9, 10, 52 Although DDX58 has not been previously associated with HIV infection, DDX58 is involved in antiviral innate immunity. 53, 54 We also found the transcript encoding IFIH1 , a pattern recognition receptor functioning as an IFN-induced helicase, was down-regulated.…”

Different Expression of Interferon-Stimulated Genes in Response to HIV-1 Infection in Dendritic Cells Based on Their Maturation State

“…It has been previously shown that HIV-1 infection of monocytes and DCs triggers different cellular pathways (40)(41)(42)(43)(44) and results in differential gene activation. In order to obtain a global assessment of gene expression changes induced by productive HIV-1 infection in IDCs and MDCs, microarray analyses comparing cells noninfected and infected with VSV-pseudotyped HIV-1 virus carrying Vpx were performed at the same time points (Fig.…”