Terminal diols as efficient substrates for transglycosylational activity of NAD glycohydrolase

Linear terminal alkane-diols have been shown to function as more efficient substrates of the transglycosylational activity of NAD+ glycohydrolase (NADase) than the corresponding respective 1-alkanols. A series of eight alkane-diols from ethane-1,2- to nonane-1,9-diols underwent an O-ADP-ribosylation in the incubation reaction with NAD/NADase to provide the corresponding ribosylated products. The structural properties of these products were characterized by 1H NMR and MS spectrometries. No substantial double ADP-ribosylation of the two hydroxy functions was observed which was initially expected in the diols of higher carbon number.

Enhancing activity of mycobacterial cell-derived adjuvants on immunogenicity of recombinant human hepatitis B virus vaccine

In a previous study, we demonstrated that a lipophilic derivative of muramyl dipeptide [MDP-Lys(L18)] augmented antibody response to recombinant human hepatitis B surface antigen (rhHBsAg) when it was co-immunized with rhHBsAg solubilized in PBS. Here, we examined adjuvant activity of two bacterial cell-derived adjuvants such as Bacillus Calmette-Guérin cell wall skeleton (BCG-CWS) and trehalose-6,6'-dimycolate (TDM), to enhance immunogenicity of rhHBsAg, comparing their activity with that of MDP-Lys(L18). In an animal model where mice were immunized subcutaneously (s.c.) with rhHBsAg (25 micrograms/mouse) admixed with 100 micrograms/mouse of BCG-CWS (Vac/BCG-CWS) or 50 micrograms/mouse of TDM (Vac/TDM) in o/w emulsion formulation, both mice immunized with Vac/BCG-CWS and Vac/TDM showed higher antibody titres to HB antigen than those of mice immunized with the recombinant vaccine alone. The activity of BCG-CWS and TDM to enhance antibody induction seemed to be almost the same with that of MDP-Lys(L18). Furthermore, the enhanced antibody response raised by these adjuvants was shown to be due to high titres of HB antigen-specific IgG1. In addition, the activity of these three adjuvants to enhance antibody response was shown to be higher than that of the present clinical vaccine, aluminium hydroxide-attached rhHBsAg (rhHBsAg-alum). In an analysis of delayed-type hypersensitivity (DTH) reaction where mice were immunized with rhHBsAg admixed with or without each adjuvant in o/w emulsion and followed by intrafootpad (i.f.) injection of rhHBsAg 4 weeks after immunization, mice immunized with Vac/BCG-CWS and Vac/TDM as well as Vac/MDP-Lys(L18) showed a significant increment of swelling reaction. These results suggest that BCG-CWS, TDM and MDP-Lys(L18) are potential adjuvants to enhance the immunogenicity of rhHBsAg to induce humoral and cellular responses.

Characterization of neutralizing monoclonal antibody escape mutants of Hantaan virus 76118

Neutralizing monoclonal antibody (MAb) escape mutants of Hantaan virus were generated using MAbs to envelope protein G1 (16D2) and G2 (11E10). The mutant viruses (mu16D2 and mu11E10), lacked reactivity only to the selecting MAb, or a MAb belonging to the same antigenic site. Both mutants had a single amino acid (a.a.) substitution. The a.a. substitution, found in mu16D2, was different from that found in another mutant selected with the same MAb (16D2). Although MAb 11E10 immunoprecipitated G2 protein, a deduced a.a. substitution was located in the G1 region. These results suggest that antigenic sites defined by neutralizing MAbs are composed of discontinuous epitopes over the G1 and G2 proteins. Mutant 11E10 showed a significant decrease in virulence in suckling mice. A virulence revertant of mu11E10, selected through passages in suckling mice brain, showed exactly the same deduced a.a. sequence as mu11E10 and still was not neutralized by MAb 11E10. Since mutant 16D2 was virulent for suckling mice, neutralization related epitopes found with MAbs 11E10 and 16D2 were independent of pathogenicity in BALB/c mice.

Effect of MDP-Lys(L18) as a mucosal immunoadjuvant on protection of mucosal infections by Sendai virus and rotavirus

To examine the effect of MDP-Lys(L18), a derivative of muramyl dipeptide (MDP), as a mucosal immunoadjuvant, we investigated its activity to augment host resistance against mucosal infections by Sendai virus and rotavirus in mice. In an experimental infection model using suckling mice (10-day-old) inoculated perorally (p.o.) with 1.5 x 10(6) p.f.u. mouse-1 of rotavirus strain SA11, intrarectal (i.r.) as well as p.o. administration of MDP-Lys(L18) (50 micrograms mouse-1) prior to virus infection markedly reduced rotavirus-induced diarrhea. Furthermore, when MDP-Lys(L18) was administered p.o. (1 mg mouse-1), i.r. (300 micrograms mouse-1) or intranasally (i.n., 100 micrograms mouse-1) various days before Sendai virus infection (2.6 x 10(4) HAD mouse-1), all the mucosal administration of MDP-Lys(L18) significantly protected a lethal infection of Sendai virus, showing a dose-dependent manner. However, the efficacy of MDP-Lys(L18) to induce the prophylactic activity against the viruses somewhat varied according to the administration route and timing. In time course analysis of virus isolation in vivo, the mice administered with MDP-Lys(L18) exhibited a significant reduction of both viruses in the lungs for Sendai virus and in the bowels for rotavirus. These results suggest that MDP-Lys(L18) is a potent mucosal immunoadjuvant to enhance nonspecific host resistance against two mucosal infectious viruses, Sendai virus and rotavirus.

Effect of MDP-Lys(L18), a derivative of MDP, on enhancing host resistance against Hantaan virus infection in newborn mice

We examined the effect of MDP-Lys(L18), a lipophilic derivative of muramyl dipeptide, on the enhancement of host resistance against virus infection in newborn mice. Newborn mice were inoculated with 4 LD50/mouse of Hantaan virus strain 76-118 (HTN) one day after birth. Mice given 100 micrograms/mouse of MDP-Lys(L18) before infection exhibited significantly higher survival rates than those of non-treated mice. The effect of MDP-Lys(L18) was also restorative when given to the mice 4 or 7 days after infection. The titers of virus isolated from the lungs and spleens 12 days after infection, were about 30-times lower in MDP-Lys(L18)-treated (lung: 1.0 x 10(3) FFU; spleen: 6.8 x 10(1) FFU/mouse), than those of non-treated mice (lung: 3.4 x 10(4) FFU; spleen: 1.9 x 10(3) FFU/mouse). Furthermore, the virus was undetectable in the brains of MDP-Lys(L18)-treated mice, whereas viruses were isolated from 3 of 6 non-treated mice. MDP-Lys(L18) augmented the number of peripheral leukocytes and splenocytes, as well as mitogenic responses of the cells from bone marrow and spleen of newborn mice. These results suggest that MDP-Lys(L18) enhanced the resistance of newborn mice against HTN virus in a systemic infection model, and that this mechanism is involved in the enhancement of hematopoiesis and responsiveness of immune-related cells to mitogens.

Inhibitory effect of tumor metastasis in mice by saponins, ginsenoside-Rb2, 20(R)- and 20(S)-ginsenoside-Rg3, of red ginseng

We examined the inhibitory effect of two saponin preparations from Red ginseng, 20(R)- and 20(S)-ginsenoside-Rg3, in comparison with that of ginsenoside-Rb2, on lung metastasis produced by two highly metastatic tumor cells, B16-BL6 melanoma and colon 26-M3.1 carcinoma, in syngeneic mice. In an in vitro analysis, both saponin preparations showed a significant inhibition of adhesion to fibronectin (FN) and laminin (LM) by B16-BL6 melanoma. Similarly, they significantly inhibited the invasion of B16-BL6 cells into the reconstituted basement membrane (Matrigel)/FN in a dose-dependent manner. In an experimental metastasis model using B16-BL6 melanoma, consecutive intravenous (i.v.) administrations of 100 micrograms/mouse of 20(R)- or 20(S)-ginsenoside-Rg3 1, 2, 3 and 4 d after tumor inoculation led to a significant decrease in lung metastasis. The inhibitory effect of i.v. administration of both ginseng saponins on the tumor metastasis of B16-BL6 melanoma was also recognized in a low dose of 10 micrograms/mouse. The oral administration (p.o.) of both saponins (100-1000 micrograms/mouse) induced a significant decrease in lung metastasis of B16-BL6 melanoma. Moreover, both ginseng saponins were effective in inhibiting of lung metastasis produced by colon 26-M3.1 carcinoma. When 20(R)- or 20(S)-ginsenoside-Rg3 was orally administered consecutively after tumor inoculation in a spontaneous metastasis model using B16-BL6 melanoma, both of them significantly inhibited lung metastasis. In the experiment involving neovasculization by tumor cells in vivo, both mice groups given each saponin preparation after tumor inoculation exhibited a significant decrease in the number of blood vessels oriented toward the tumor mass, with no repression of tumor size. These findings suggest that both ginseng saponins, 20(R)- and 20(S)-ginsenoside-Rg3, possess an ability to inhibit the lung metastasis of tumor cells, and the mechanism of their antimetastatic effect is related to inhibition of the adhesion and invasion of tumor cells, and also to anti-angiogenesis activity.