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ABSTRACT: The chicken MHC B contains two classical class I genes, BF1 and BF2, with the exception of two related haplotypes lacking BF1 due to insertion/rearrangement. In light of functional specialization of BF1 and BF2 molecules, we were interested in evaluating their relative expression at the mRNA level. We evaluated several MHC haplotypes
for class I gene expression by RT-quantitative PCR. BF1 transcript levels were approximately two- to fivefold lower than BF2, with the exception of one haplotype in which BF1 expression was very low. To investigate molecular explanations for differences in BF locus or allele expression, we determined nucleotide sequences of Enhancer A and proximal promoter elements of nine different
BF1 alleles, as well as their signal peptide sequences. Results showed that all BF1 alleles exhibit conservation of most of the identified promoter elements, but divergence from the Enhancer A sequence identified
in the more highly expressed BF2 locus. Nonetheless, extensive BF1 allelic polymorphism was found in the promoter region and in the signal peptide, with two strongly separated allelic lineages
identified for both. Patterns of promoter lineages, signal peptide lineages, and exon 2 mature protein coding sequences in
individual BF1 alleles suggest that recombination among these elements has contributed to diversification of BF1 alleles. Finally, identification of a novel inactivating mutation in one BF1 allele suggests past selective pressure to eliminate BF1 function.
Immunogenetics 04/2012; 61(4):289-302. · 2.93 Impact Factor
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ABSTRACT: Myxovirus-resistance (Mx) proteins are produced by host cells in response to type I interferons, and some members of the Mx gene family in mammals have been shown to limit replication of influenza and other viruses. According to an early report, chicken Mx1 variants encoding Asn at position 631 have antiviral activity, whereas variants with Ser at 631 lack activity in experiments evaluating Mx1 complementary DNA (cDNA) expressed ectopically in a cell line. We evaluated whether the Mx1 631 dimorphism influenced pathogenesis of highly pathogenic avian influenza virus (HPAIV) infection in chickens of two commercial broiler lines, each segregating for Asn631 and Ser631 variants. Following intranasal infection with HPAIV strain A/Chicken/Queretaro/14588-19/1995 H5N2, chickens homozygous for Asn631 allele were significantly more resistant to disease based on early mortality, morbidity, or virus shedding than Ser631 homozygotes. Higher amounts of splenic cytokine transcripts were observed in the Ser631 birds after infection, consistent with higher viral loads seen in this group and perhaps contributing to their higher morbidity. Nucleotide sequence determination of Mx1 cDNAs demonstrated that the Asn631 variants in the two chicken lines differed at several amino acid positions outside 631. In vitro experiments with a different influenza strain (low pathogenicity) failed to demonstrate an effect of Mx1 Asn631 on viral replication suggesting that in vivo responses may differ markedly from in vitro, or that choice of virus strain may be critical in demonstrating effects of chicken Mx1. Overall, these studies provide the first evidence that Mx1 has antiviral effects in chickens infected with influenza virus.
Immunogenetics 02/2011; 63(6):363-75. · 2.93 Impact Factor
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ABSTRACT: Interferon (IFN)-induced antiviral activity in cells forms an important early line of defense against viral pathogens. IFN-induced mediators are well documented in mammals, with one of the best-characterized antiviral proteins being Mx. In chickens, many alleles of Mx have been described, but functionally only the polymorphism at a site encoding residue 631 in the protein determines differential antiviral activity against vesicular stomatitis virus and influenza virus in transfection experiments. The role of chicken Mx has not been assessed with regard to infectious bursal disease virus (IBDV), an important pathogen of chickens. To examine the role of chicken IFNalpha and the Mx631 single-nucleotide polymorphism against IBDV, chicken embryo fibroblast cultures (CEF) that differed in Mx genotype (antivirally positive Mx Asn631 or antivirally negative Mx Ser631) were treated with IFNalpha and viral yield was assessed following infection with D78 vaccine-strain IBDV. IFNalpha was shown to have strong antiviral activity in this system in terms of reduced virus yield. Furthermore, the reduction in viral yield did not differ significantly among Mx genotypes, indicating that Mx Asn631 is not a pivotal determinant of resistance to this strain of IBDV in CEF.
Avian Diseases 06/2010; 54(2):802-6. · 1.46 Impact Factor
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Avian Diseases - AVIAN DIS. 01/2010; 54(2):802-806.
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ABSTRACT: The first standard nomenclature for the chicken (Gallus gallus) major histocompatibility (B) complex published in 1982 describing chicken major histocompatibility complex (MHC) variability is being revised to include subsequent findings. Considerable progress has been made in identifying the genes that define this polymorphic region. Allelic sequences for MHC genes are accumulating at an increasing rate without a standard system of nomenclature in place. The recommendations presented here were derived in workshops held during International Society of Animal Genetics and Avian Immunology Research Group meetings. A nomenclature for B and Y (Rfp-Y) loci and alleles has been developed that can be applied to existing and newly defined haplotypes including recombinants. A list of the current standard B haplotypes is provided with reference stock, allele designations, and GenBank numbers for corresponding MHC class I and class IIbeta sequences. An updated list of proposed names for B recombinant haplotypes is included, as well as a list of over 17 Y haplotypes designated to date.
Immunogenetics 08/2004; 56(4):261-79. · 2.93 Impact Factor
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ABSTRACT: Neoplastic cells are believed to evade the immune system due, in part, to their inability to successfully provide a secondary, costimulatory signal for a T lymphocyte proliferative response. This report describes the generation and investigation of genetically engineered canine mammary tumor (CMT) cells that express canine B7-1, canine B7-2, or human B7-2. These transfected cells were used as stimulators in an allogeneic, costimulation assay. CMT cells transfected with canine B7-1 induced the greatest proliferation (7-fold increase), followed by CMT cells transfected with canine B7-2 (5-fold increase). The specificity of the canine B7-2 stimulatory response was demonstrated by a 38% reduction in proliferation caused by an anti-canine B7-2 blocking antibody. These results suggest that canine mammary tumor cells transfected with canine B7-1 or canine B7-2 may be useful for immunotherapeutic purposes.
Anticancer research 22(5):2567-74. · 1.73 Impact Factor
