Preferential Inhibition of Herpes-Group Viruses by Phosphonoacetic Acid: Effect on Virus DNA Synthesis and Virus-Induced DNA Polymerase Activity

In tissue culture phosphonoacetic acid (PAA) specifically inhibited DNA synthesis of human cytomegalovirus (CMV), murine CMV, simian CMV, Epstein-Barr virus, and Herpesvirus saimiri. Fifty to one hundred micrograms per milliliter PAA completely inhibited viral DNA synthesis with no significant damage to host cell DNA synthesis. In vitro DNA polymerization assays showed that 10 μg/ml of PAA specifically inhibited partially purified human CMV-induced DNA polymerase, while little inhibition of host-cell DNA polymerase activity was found. The specific inhibition of herpes-group virus DNA synthesis with little toxicity to host cells suggests that PAA has great potential as an antiherpesvirus therapeutic agent.     

Influence of citric acid amendments on the availability of weathered PCBs to plant and earthworm species

A series of small and large pot trials were conducted to assess the phytoextraction potential of several plant species for weathered polychlorinated biphenyls (PCBs) in soil (105 microg/g Arochlor 1268). In addition, the effect of citric acid on PCB bioavailability to both plants and earthworms was assessed. Under small pot conditions (one plant, 400 g soil), three cucurbits (Cucurbita pepo ssp pepo [zucchini] and ssp ovifera [nonzucchini summer squash], Cucumis sativus, cucumber) accumulated up to 270 microg PCB/g in the roots and 14 microg/g in the stems, resulting in 0.10% contaminant removal from soil. Periodic 1 mM subsurface amendments of citric acid increased the stem and leaf PCB concentration by 330 and 600%, respectively, and resulted in up to a 65% increase in the total amount of contaminant removed from soil. Although citric acid at 10 mM more than doubled the amount of PCB desorbed in abiotic batch slurries, contaminant accumulation by two earthworm species (Eisenia foetida and Lumbricus terrestris) was unaffected by citric acid at 1 and 10 mM and ranged from 11-15 microg/g. Two large pot trials were conducted in which cucurbits (C. pepo ssp pepo and ssp ovifera, C. sativus) and white lupin (Lupinus albus) were grown in 70 kg of PCB-contaminated soil White lupin was the poorest accumulator of PCBs, with approximately 20 microg/g in the roots and 1 microg/g in the stems. Both C. pepo ssp ovifera (summer squash) and C. sativus (cucumber) accumulated approximately 65-100 microg/g in the roots and 6-10 microg/g in the stems. C. pepo ssp pepo (zucchini) accumulated significantly greater levels of PCB than all other species, with 430 microg/g in the roots and 22 microg/g in the stems. The mechanism by which C. pepo spp pepo extracts and translocates weathered PCBs is unknown, but confirms earlier findings on the phytoextraction of other weathered persistent organic pollutants such as chlordane, p,p'-DDE, and polycyclic aromatic hydrocarbons.     

Animal models for protein respiratory sensitizers

Protein induced respiratory hypersensitivity, particularly atopic disease in general, and allergic asthma in particular, has increased dramatically over the last several decades in the US and other industrialized nations as a result of ill-defined changes in living conditions in modern western society. In addition, work-related asthma has become the most frequently diagnosed occupational respiratory illness. Animal models have demonstrated great utility in developing an understanding of the etiology and mechanisms of many diseases. A few models been developed as predictive models to identify a protein as an allergen or to characterize its potency. Here we describe animal models that have been used to investigate and identify protein respiratory sensitizers. In addition to prototypical experimental design, methods for exposure route, sample collection, and endpoint assessment are described. Some of the most relevant endpoints in assessing the potential for a given protein to induce atopic or allergic asthma respiratory hypersensitivity are the development of cytotropic antibodies (IgE, IgG1), eosinophil influx into the lung, and airway hyperresponsiveness to the sensitizing protein and/or to non-antigenic stimuli (Mch). The utility of technologies such as PCR and multiplexing assay systems is also described. These models and methods have been used to elucidate the potential for protein sources to induce allergy, identify environmental conditions (pollutants) to impact allergy responsiveness, and establish safe exposure limits. As an example, data are presented from an experiment designed to compare the allergenicity of a fungal biopesticide Metarhizium anisopliae (MACA) crude extract with the one of its components, conidia (CON) extract.     

A Salmonella typhimurium mutant unable to utilize fatty acids and citrate is avirulent and immunogenic in mice

Salmonella typhimurium SR-11 is extremely virulent at a dose as low as 10⁵ colony forming units (cfu) when administered perorally to BALB/c mice. Utilizing mini-transposon mutagenesis, a mutant of S. typhimurium SR-11 was isolated that was unable to utilize oleate and citrate as carbon sources. This mutant, designated S. typhimurium SR-11 Fad⁻ (Fatty acid), was found to utilize sugars under cya/crp control as sole carbon sources, suggesting that the mutation is not in either of these genes. In addition, SR-11 Fad⁻ utilized pyruvate and succinate, but was unable to utilize either acetate or isocitrate as sole carbon source. In contrast to SR-11, SR-11 Fad⁻ was found to be avirulent, i.e. BALB/c mice were completely healthy after oral infection with 10⁹ S. typhimurium SR-11 Fad⁻ cells. Moreover, 21 days after SR-11 Fad⁻ infection, BALB/c mice were found to be protected against an oral challenge with 10⁹ cells of S. typhimurium SR-11.