Search

An estimated $1 billion was lost in decontaminating areas exposed to anthrax in the 2001 attacks. To counter the threat of biological attacks, an effective 'green' decontaminant is vital to minimize the consequences of such attacks. The objective of our research was to study the ability of glycoconjugate ligands to decontaminate Bacillus cereus spores on hard surfaces. Polyvalent glycoconjugates (also known as neoglycoconjugates) were tested during decontamination of B. cereus spores. Resulting colony forming units (CFU) of viable spores were a direct evidence of glycoconjugate decontamination efficacy. Our results indicate a substantial, decreasing CFU count due to defensive and simultaneous actions of glycoconjugates compared to spores only used as controls. Decontamination of B. cereus spores was most efficiently and consistently achieved using Galalpha1-->3GalNAcbeta-PAA-flu glycoconjugate under both defensive and simultaneous conditions. Atomic force microscopy (AFM) allowed us to visualize decontamination at the nanoscale level using glycoconjugates. AFM reveals the size of glycoconjugate agglomerates (clusters) and a noticeably different morphology of glycoconjugate-treated spores during decontamination. Morphological features of untreated spores disappear under a thin layer of glycoconjugate solution. This thin layer is formed due to the defensive action of glycoconjugates. Simultaneous action has shown agglomeration of glycoconjugates in solution with B. cereus spores in glycoconjugate suspensions. Glycoconjugates might be useful for the development of an environment-friendly decontaminant of bacterial spores.

Diseases caused by Bacillus spores might be attenuated if macrophages were able to kill the spores on exposure. Glycoconjugate-bearing polymers, which have been shown to bind to Bacillus spores, were tested for modulation of phagocytosis of B. cereus spores. Without glycoconjugate activation, murine macrophages were ineffective at killing Bacillus spores during phagocytosis. In the presence of glycoconjugates, however, the macrophages efficiently killed the organisms. The glycoconjugates were shown to have a protective influence, sparing macrophages from spore-induced cell death. Very low concentrations of the glycoconjugates prevented macrophage cell death, as shown by lactate dehydrogenase (LDH) release and trypan blue assays. Increased levels of inducible nitric oxide (NO) production by the macrophages in the presence of glycoconjugates suggested that the glycoconjugates provide an activation signal to the macrophages. These results suggest that glycoconjugates promote the killing of Bacillus spores by blocking spore-induced macrophage cell death, while increasing their activation level. Polymeric glycoconjugates may suggest novel approaches to improve existing vaccines as well as prevent and treat infections incurred through either B. cereus or B. anthracis spores.

Infections caused by Bacillus spores can be attenuated if the intracellular killing of the organism by macrophages can be enhanced. Glycoconjugate-bearing polymers, which selectively bind to Bacillus spores, were tested for modulation of intracellular killing when added prior to, during, and following macrophage exposure to B. cereus spores. In the absence of glycoconjugates, murine macrophages were ineffective at killing Bacillus spores. In presence of glycoconjugates, however, macrophages efficiently killed spores, whether the glycoconjugates were added to the cells prior to, during, and following spore addition. Glycoconjugates were shown to exert a protective influence on macrophages and increase their activation, as evidenced by viability and lactate dehydrogenase release assays. Increased levels of nitric oxide production by macrophages pretreated with glycoconjugates suggest that, under these conditions, glycoconjugates provide an activation signal to macrophages. These results indicate that glycoconjugates promote killing of Bacillus spores, while increasing macrophage activation level and viability. The selection of glycoconjugate ligands bearing immunomodulating properties could be exploited for vaccine and/or immunomodulator development and/or for the improvement of existing vaccines against B. cereus and B. anthracis.

The occurrence of scanning electron microscopy (SEM) and atomic force microscopy (AFM) side-by-side is becoming increasingly common in analytical research. This article shows microscopy techniques to image Bacillus spores, to measure spore dimensions, and to demonstrate how these methods provide supplementary information to study plasma torch effects. This paper demonstrates that observed morphologies of spores before and after exposure to a plasma torch are remarkably different. The use of SEM and AFM as a tool complex enables examination of spore morphology and dimensions as well as their alterations during decontamination using plasma torch. [ABSTRACT FROM AUTHOR]

The air plasma effluent of an arc-seed microwave torch is used to kill bacterial spores contained inside an envelope. The torch is operated at a 60-Hz periodic mode (with about 40% duty cycle) and runs stably at a low airflow rate (e.g., 0.3931/s). The images of plasma torch plumes show that the arc loop of the discharge prolongs from the electrodes by nearly 3 cm and microwave energizes the charge particles along the arc loop considerably. The emission spectroscopy of the torch indicates that the plasma effluent contains an abundance of reactive atomic oxygen. Bacillus cereus is chosen for the biological agent in the decontamination experiment. The experiment and the decontamination efficacy of this torch are presented. The averaged temperature inside the envelope is measured to be less than 40 °C, thus ruling out the thermal decontamination mechanism. [ABSTRACT FROM AUTHOR]