Highly sensitive detection of influenza virus in saliva by real-time PCR method using sugar chain-immobilized gold nanoparticles; application to clinical studies.

A highly sensitive and convenient method for detecting influenza virus was developed using modified end-point melt curve analysis of a RT-qPCR SYBR Green method and influenza virus-binding sugar chain-immobilized gold-nanoparticles (SGNP). Because SGNPs capture influenza viruses, the virus-SGNP complex was separated easily by centrifugation. Viral RNA was detected at very low concentrations, suggesting that SGNP increased sensitivity compared with standard methods. This method was applied to clinical studies. Influenza viruses were detected in saliva of patients or inpatients who had been considered influenza-free by a rapid diagnostic assay of nasal swabs. Furthermore, the method was applied to a human trial of prophylactic anti-influenza properties of yogurt containing Lactobacillus acidophilus L-92. The incidence of influenza viruses in saliva of the L-92 group was found to be significantly lower compared to the control group. Thus, this method was useful for monitoring the course of anti-influenza treatment or preventive measures against nosocomial infection.

Proliferation of the hyperthermophilic archaeon Pyrobaculum islandicum by cell fission.

Pyrobaculum islandicum is a hyperthermophilic archaeon. P. islandicum cells have been suggested to multiply by constriction, budding and branching, as no septa were observed in cells by phase-contrast light microscopy. In this study, we observed the cells using transmission electron microscopy, scanning electron microscopy, and light microscopy with dark-field image analyses, and we report binary fission via septum formation to be the main mode of P. islandicum's proliferation. "Long cells" reported previously were found to comprise several cylindrical cells that align in tandem.

Possible involvement of put A gene in Helicobacter pylori colonization in the stomach and motility.

H. pylori is a gram-negative bacterium associated with gastric inflammation and peptic ulcer and considered a risk factor for gastric cancer in its natural habitat. However, the energy metabolism of H. pylori in the stomach remains to be clarified. H. pylori shows rather high respiratory activity with L-proline and significantly large amounts of L-proline are present in the gastric juice from H. pylori infected patients. We constructed a disrupted mutant of the put A gene, which encodes the proline utilization A (Put A) flavin-linked enzyme, in order to examine the role of put A in the gastric colonization of H. pylori. The put A disrupted mutant, DeltaputA, was constructed by inserting a chloramphenicol resistant gene into put A. DeltaputA did not show respiratory activity using L-proline and could not incorporate L-proline into cells. DeltaputA also did not show motility in response to amino acids and did not display the swarming activity observed with the wild-type. DeltaputA had lost its ability to colonize the stomach of nude mice, an ability possessed by the wild-type. These findings indicate that put A may play an important role in H. pylori colonization on the gastric mucus layer.

Evidence of immunostimulating lipoprotein existing in the natural lipoteichoic acid fraction.

Lipoteichoic acid (LTA) is a cell surface glycoconjugate of gram-positive bacteria and is reported to activate the innate immune system. We previously reported that purified LTA obtained from Enterococcus hirae has no immunostimulating activity, but a subfraction (Eh-AF) in an LTA fraction possesses activity. In this study, we established a mouse monoclonal antibody neutralizing the activity of Eh-AF and investigated its inhibitory effects. Monoclonal antibody (MAbEh1) was established by the immunization of BALB/c mice with Eh-AF, followed by hybridoma screening based on its inhibitory effect for the production of interleukin-6 (IL-6) induced by Eh-AF. MAbEh1 neutralized the production of IL-6 by LTA fraction from not only E. hirae but also Staphylococcus aureus, while it failed to block that of lipopolysaccharide, suggesting that the antibody recognized a common active structure(s) in LTA fractions. Synthetic glycolipids in these LTAs did not induce cytokine production, at least in our system. Interestingly, the antibody was found to inhibit the activity of immunostimulating synthetic lipopeptides, Pam(3)CSK(4) and FSL-1. These results suggest that MAbEh1 neutralizes the activity of lipoprotein-like compounds which is responsible for the activity of the LTA fraction of E. hirae and S. aureus.

Lipoprotein is a predominant Toll-like receptor 2 ligand in Staphylococcus aureus cell wall components.

Lipoteichoic acid (LTA) derived from Staphylococcus aureus is reported to be a ligand of Toll-like receptor 2 (TLR2). In this study, we demonstrated that lipoproteins obtained from S. aureus are potent activators of TLR2. A fraction obtained by Triton X-114 phase partitioning activated cells through TLR2. The fraction contained proteins and LTA. The activity was detected in compounds in a mass range of 12-40 kDa. Proteinase K digested the active compounds into lower molecular weight active materials <10 kDa. In contrast, hydrofluoric acid treatment, which decomposes LTA, did not alter the molecular mass of the active compounds. Further, most of the activity was abrogated by lipoprotein lipase digestion. These results suggested that lipoproteins are predominant TLR2 ligands in S. aureus cell wall components.