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  • American Society for Microbiology  (4)
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  • American Society for Microbiology  (4)
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  • 1
    In: Journal of Virology, American Society for Microbiology, Vol. 92, No. 6 ( 2018-03-15)
    Abstract: Feline immunodeficiency virus (FIV) infection in domestic cats is the smallest usable natural model for lentiviral infection studies. FLA-E*01801 was applied to FIV AIDS vaccine research. We determined the crystal structure of FLA-E*01801 complexed with a peptide derived from FIV (gag positions 40 to 48; RMANVSTGR [RMA9]). The A pocket of the FLA-E*01801 complex plays a valuable restrictive role in peptide binding. Mutation experiments and circular-dichroism (CD) spectroscopy revealed that peptides with Asp at the first position (P1) could not bind to FLA-E*01801. The crystal structure and in vitro refolding of the mutant FLA-E*01801 complex demonstrated that Glu 63 and Trp 167 in the A pocket play important roles in restricting P1D. The B pocket of the FLA-E*01801 complex accommodates M/T/A/V/I/L/S residues, whereas the negatively charged F pocket prefers R/K residues. Based on the peptide binding motif, 125 FLA-E*01801-restricted FIV nonapeptides (San Diego isolate) were identified. Our results provide the structural basis for peptide presentation by the FLA-E*01801 molecule, especially A pocket restriction on peptide binding, and identify the potential cytotoxic T lymphocyte (CTL) epitope peptides of FIV presented by FLA-E*01801. These results will benefit both the reasonable design of FLA-E*01801-restricted CTL epitopes and the further development of the AIDS vaccine. IMPORTANCE Feline immunodeficiency virus (FIV) is a viral pathogen in cats, and this infection is the smallest usable natural model for lentivirus infection studies. To examine how FLA I presents FIV epitope peptides, we crystallized and solved the first classic feline major histocompatibility complex class I (MHC-I) molecular structure. Surprisingly, pocket A restricts peptide binding. Trp 167 blocks the left side of pocket A, causing P1D to conflict with Glu 63 . We also identified the FLA-E*01801 binding motif X (except D)-(M/T/A/V/I/L/S)-X-X-X-X-X-X-(R/K) based on structural and biochemical experiments. We identified 125 FLA-E*01801-restricted nonapeptides from FIV. These results are valuable for developing peptide-based FIV and human immunodeficiency virus (HIV) vaccines and for studying how MHC-I molecules present peptides.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1495529-5
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  • 2
    In: Journal of Virology, American Society for Microbiology, Vol. 91, No. 14 ( 2017-07-15)
    Abstract: A single dominantly expressed allele of major histocompatibility complex class I (MHC I) may be responsible for the duck's high tolerance to highly pathogenic influenza A virus (HP-IAV) compared to the chicken's lower tolerance. In this study, the crystal structures of duck MHC I ( Anpl -UAA*01) and duck β2-microglobulin (β2m) with two peptides from the H5N1 strains were determined. Two remarkable features were found to distinguish the Anpl -UAA*01 complex from other known MHC I structures. A disulfide bond formed by Cys 95 and Cys 112 and connecting the β5 and β6 sheets at the bottom of peptide binding groove (PBG) in Anpl -UAA*01 complex, which can enhance IAV peptide binding, was identified. Moreover, the interface area between duck MHC I and β2m was found to be larger than in other species. In addition, the two IAV peptides that display distinctive conformations in the PBG, B, and F pockets act as the primary anchor sites. Thirty-one IAV peptides were used to verify the peptide binding motif of Anpl -UAA*01, and the results confirmed that the peptide binding motif is similar to that of HLA-A*0201. Based on this motif, approximately 600 peptides from the IAV strains were partially verified as the candidate epitope peptides for Anpl -UAA*01, which is a far greater number than those for chicken BF2*2101 and BF2*0401 molecules. Extensive IAV peptide binding should allow for ducks with this Anpl -UAA*01 haplotype to resist IAV infection. IMPORTANCE Ducks are natural reservoirs of influenza A virus (IAV) and are more resistant to the IAV than chickens. Both ducks and chickens express only one dominant MHC I locus providing resistance to the virus. To investigate how MHC I provides IAV resistance, crystal structures of the dominantly expressed duck MHC class I (p Anpl -UAA*01) with two IAV peptides were determined. A disulfide bond was identified in the peptide binding groove that can facilitate Anpl -UAA*01 binding to IAV peptides. Anpl -UAA*01 has a much wider recognition spectrum of IAV epitope peptides than do chickens. The IAV peptides bound by Anpl -UAA*01 display distinctive conformations that can help induce an extensive cytotoxic T lymphocyte (CTL) response. In addition, the interface area between the duck MHC I and β2m is larger than in other species. These results indicate that HP-IAV resistance in ducks is due to extensive CTL responses induced by MHC I.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1495529-5
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  • 3
    Online Resource
    Online Resource
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 1 ( 2022-02-23)
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 1 ( 2022-02-23)
    Abstract: Mastitis, a highly prevalent disease in dairy cows, is commonly caused by local infection of the mammary gland. Our previous studies have suggested that the gut microbiota plays an important role in the development of mastitis in mice. However, the effects of rumen microbiota on bovine mastitis and the related mechanisms remain unclear. In this study, we assessed the effects and mechanisms of rumen microbiota on bovine mastitis based on the subacute rumen acidosis (SARA) model induced by feeding Holstein Frisian cows a high-concentrate diet for 8 weeks. Then, the inflammatory responses in the mammary gland and the bacterial communities of rumen fluid, feces, and milk were analyzed. The results showed that SARA induced mastitis symptoms in the mammary gland; activated a systemic inflammatory response; and increased the permeability of the blood-milk barrier, gut barrier, and rumen barrier. Further research showed that lipopolysaccharides (LPS), derived from the gut of SARA cows, translocated into the blood and accumulated in the mammary glands. Furthermore, the abundance of Stenotrophomonas was increased in the rumen of SARA cows, and mastitis was induced by oral administration of Stenotrophomonas in lactating mice. In conclusion, our findings suggested that mastitis is induced by exogenous pathogenic microorganisms as well as by endogenous pathogenic factors. Specifically, the elevated abundance of Stenotrophomonas in the rumen and LPS translocation from the rumen to the mammary gland were important endogenous factors that induced mastitis. Our study provides a foundation for novel therapeutic strategies that target the rumen microbiota in cow mastitis. IMPORTANCE Mastitis is a common and frequently occurring disease of humans and animals, especially in dairy farming, which has caused huge economic losses and brought harmful substance residues, drug-resistant bacteria, and other public health risks. The traditional viewpoint indicates that mastitis is mainly caused by exogenous pathogenic bacteria infecting the mammary gland. Our study found that the occurrence of mastitis was induced by the endogenous pathway. Evidence has shown that rumen-derived LPS enters the mammary gland through blood circulation, damaging the blood-milk barrier and then inducing inflammation of the mammary gland in cows. In addition, a higher abundance of Stenotrophomonas in the rumen was closely associated with the development of mastitis. This study provides a basis for novel therapeutic strategies that exploit the rumen microbiota against mastitis in cows.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 2807133-5
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  • 4
    In: Journal of Virology, American Society for Microbiology, Vol. 90, No. 15 ( 2016-08), p. 6625-6641
    Abstract: The lack of a peptide-swine leukocyte antigen class I (pSLA I) complex structure presents difficulties for the study of swine cytotoxic T lymphocyte (CTL) immunity and molecule vaccine development to eliminate important swine viral diseases, such as influenza A virus (IAV). Here, after cloning and comparing 28 SLA I allelic genes from Chinese Heishan pigs, pSLA-3*hs0202 was crystalized and solved. SLA-3*hs0202 binding with sβ2m and a KMNTQFTAV (hemagglutinin [HA]-KMN9) peptide from the 2009 pandemic swine H1N1 strain clearly displayed two distinct conformations with HA-KMN9 peptides in the structures, which are believed to be beneficial to stimulate a broad spectrum of CTL immune responses. Notably, we found that different HA-KMN9 conformations are caused, not only by the flexibility of the side chains of residues in the peptide-binding groove (PBG), but also by the skewing of α1 and α2 helixes forming the PBG. In addition, alanine scanning and circular-dichroism (CD) spectra confirmed that the B, D, and F pockets play critical biochemical roles in determining the peptide-binding motif of SLA-3*hs0202. Based on biochemical parameters and comparisons to similar pockets in other known major histocompatibility complex class I (MHC-I) structures, the fundamental motif for SLA-3*hs0202 was determined to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) by refolding in vitro and multiple mutant peptides. Finally, 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains, and two of them have been found in humans as HLA-A*0201-specific IAV epitopes. Structural and biochemical illumination of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine. IMPORTANCE We crystalized and solved the first SLA-3 structure, SLA-3*hs0202, and found that it could present the same IAV peptide with two distinct conformations. Unlike previous findings showing that variable peptide conformations are caused only by the flexibility of the side chains in the groove, the skewing of the α1 and α2 helixes is important in the different peptide conformations in SLA-3*hs0202. We also determined the fundamental motif for SLA-3*hs0202 to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) based on a series of structural and biochemical analyses, and 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains. We believe our structure and analyses of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
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