When expressed in mammalian cells, the nucleocapsid (N) and membrane (M) proteins of the severe acute respiratory syndrome coronavirus (SARS-CoV) are sufficient to form pseudoparticles. To identify region(s) of the N molecule required for pseudoparticle formation, we performed biochemical analysis of the interaction of N mutants and M in HEK293 cells. Using a peptide library derived from N, we found that amino acids 101-115 constituted a novel binding site for M. We examined the ability of N mutants to interact with M and form pseudoparticles, and our observations indicated that M bound to NDelta(101-115), N1-150, N151-300, and N301-422, but not to N1-150Delta(101-115). However, pseudoparticles were formed when NDelta(101-115) or N301-422, but not N1-150 or N151-300, were expressed with M in HEK293 cells. These results indicated that the minimum portion of N required for the interaction with M and pseudoparticle formation consists of amino acids 301-422.
and tosaka@research.twmu.ac.jp a N.M., T.O., and I.H. contributed equally to this work.
AbstractThe incidence of non-alcoholic steatohepatitis (NASH) is increasing. Because gut microbiota have been highlighted as one of the key factors in the pathogenesis of metabolic syndrome, we investigated the involvement of the bacterial component in the progression of non-alcoholic fatty liver (NAFL) to NASH. C57BL/6 mice were fed with maintenance food (MF, groups A and B) or a high caloric diet (HCD, groups C and D) for 1 month. Mice were then divided into four groups: Groups A and C were inoculated with PBS, while groups B and D were inoculated with lipopolysaccharide (LPS) plus complete Freund's adjuvant (CFA). The inoculations were performed a total of 3 times over 3 months. At 6 months, while hepatic steatosis was observed in groups C and D, cellular infiltration and fibrosis were less evident in group C than in group D. Inflammatory cytokines were upregulated in groups B and D. 16S rRNA pyrosequencing of whole colon homogenates containing faeces showed that certain bacterial groups, such as Bacteroidaceae, Peptostreptococcaceae and Erysipelotrichaceae, were increased in groups C and D. Although loading of bacterial components (LPS) resulted in hepatic inflammation in both MF-and HCD-fed mice, HCD feeding was more crucial in the progression of NAFL during the triggering phase.
Abstract:Pasteurella pneumotropica is an opportunistic pathogen in rodents. Natural infection in immunodeficient animals suggests that immunodeficiency is a major factor in P. pneumotropica pathogenesis. To understand this process, we performed clinical, pathological and bacteriological studies of immunodeficient NOD/ShiJic-scid/Jcl and immunocompetent Crlj:CD1 (ICR) mice experimentally infected with P. pneumotropica ATCC 35149. From 14 days postinoculation, some of P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice developed clinical signs of weight loss. Three of 10 P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice developed clinical signs of depression, ruffled coat, and weight loss and died at 27, 34, and 59 days postinoculation. At 35 days postinoculation, almost all P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice had lung abscesses. The bacteria were isolated from the upper and lower respiratory tracts, including the lungs, and blood. In contrast, P. pneumotropicainfected ICR mice exhibited no clinical signs or lesions. The bacteria were isolated from the upper, but not the lower respiratory tracts. We developed an animal model for understanding host interactions with P. pneumotropica.
Gut commensal microorganisms have been linked with chronic inflammation at the extra-intestinal niche of the body. The object of the study was to investigate on the chronic effects of a gut commensal Escherichia coli on extra-intestinal glands. The presence of autoimmune response was diagnosed by autoantibody levels and histological methods. Repeated injection of E. coli induced mononuclear cell inflammation in the Harderian and submandibular salivary glands of female C57BL/6 mice. Inflammation was reproduced by adoptive transfer of splenocytes to immune-deficient Rag2 knockout mice and CD4+ T cells to mature T cell-deficient TCRβ-TCRδ knockout mice. MALDI TOF mass spectrometry of the protein to which sera of E. coli-treated mice reacted was determined as the outer membrane protein A (OmpA) of E. coli. Multiple genera of the Enterobacteriaceae possessed OmpA with high amino-acid sequence similarities. Repeated injection of recombinant OmpA reproduced mononuclear cell inflammation of the Harderian and salivary glands in mice and elevation of autoantibodies against Sjögren’s-syndrome-related antigens SSA/Ro and SSB/La. The results indicated the possibility of chronic stimuli from commensal bacteria-originated components as a pathogenic factor to elicit extra-intestinal autoimmunity.
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