RESUMO
Retinoic acid-inducible gene I (RIG-I), a cytosolic pattern recognition receptor (PRR), can sense various RNA viruses, including the avian influenza virus (AIV) and infectious bursal disease virus (IBDV), and trigger the innate immune response. Previous studies have shown that mammalian RIG-I (human and mice) and waterfowl RIG-I (ducks and geese) are essential for type I interferon (IFN) synthesis during AIV infection. Like ducks, pigeons are also susceptible to infection but are ineffective propagators and disseminators of AIVs, i.e., "dead end" hosts for AIVs and even highly pathogenic avian influenza (HPAI). Consequently, we sought to identify pigeon RIG-I and investigate its roles in the detection of A/Chicken/Shandong/ZB/2007 (H9N2) (ZB07), Gansu/Tianshui (IBDV TS) and Beijing/CJ/1980 (IBDV CJ-801) strains in chicken DF-1 fibroblasts or human 293T cells. Pigeon mRNA encoding the putative pigeon RIG-I analogs was identified. The exogenous expression of enhanced green fluorescence protein (EGFP)-tagged pigeon RIG-I and caspase activation and recruitment domains (CARDs), strongly induced antiviral gene (IFN-ß, Mx, and PKR) mRNA synthesis, decreased viral gene (M gene and VP2) mRNA expression, and reduced the viral titers of ZB07 and IBDV TS/CJ-801 virus strains in chicken DF-1 cells, but not in 293T cells. We also compared the antiviral abilities of RIG-I proteins from waterfowl (duck and goose) and pigeon. Our data indicated that waterfowl RIG-I are more effective in the induction of antiviral genes and the repression of ZB07 and IBDV TS/CJ-801 strain replication than pigeon RIG-I. Furthermore, chicken melanoma differentiation associated gene 5(MDA5)/ mitochondrial antiviral signaling (MAVS) silencing combined with RIG-I transfection suggested that pigeon RIG-I can restore the antiviral response in MDA5-silenced DF-1 cells but not in MAVS-silenced DF-1 cells. In conclusion, these results demonstrated that pigeon RIG-I and CARDs have a strong antiviral ability against AIV H9N2 and IBDV in chicken DF-1 cells but not in human 293T cells.
Assuntos
Proteínas Aviárias/imunologia , Doenças das Aves/enzimologia , Doenças das Aves/imunologia , Columbidae/imunologia , RNA Helicases DEAD-box/imunologia , Imunidade Inata , Vírus da Doença Infecciosa da Bursa/fisiologia , Vírus da Influenza A Subtipo H9N2/fisiologia , Animais , Proteínas Aviárias/genética , Doenças das Aves/genética , Doenças das Aves/virologia , Galinhas , Columbidae/virologia , RNA Helicases DEAD-box/genética , Patos , Humanos , Vírus da Doença Infecciosa da Bursa/genética , Vírus da Influenza A Subtipo H9N2/genéticaRESUMO
To date, most jawed vertebrate species encode more than one immunoglobulin light (IgL) chain isotypes. It has been shown that several bird species (chickens, white Pekin or domestic duck, and zebra finches) exclusively express lambda isotype. We analyze here the genomic organization of another bird species turkey IgL genes based on the recently released genome data. The turkey IgL locus located on chromosome 17 spans approximately 75.2kb and contains a single functional V(λ) gene, twenty V(λ) pseudogenes, and a single functional J(λ)-C(λ) block. These data suggest that the genomic organization of bird IgL chain genes seems to be conserved. Ten cDNA clones from turkey Igλ chain containing almost full-length V(λ), J(λ) and C(λ) segments were acquired. The comparison of V(λ) cDNA sequences to all the germline V(λ) segments suggests that turkey species may be generating IgL chain diversity by gene conversion and somatic hypermutation like the chicken. This study provides insights into the immunoglobulin light chain genes in another bird species.
