Review of techniques for the in-situ sterilization of soil contaminated with Bacillus anthracis spores or other pathogens

This review summarizes the literature on efficacy of techniques to sterilize soil. Soil may need to be sterilized if contaminated with pathogens such as Bacillus anthracis. Sterilizing soil in-situ minimizes spread of the bio-contaminant. Soil is difficult to sterilize, with efficacy generally diminishing with depth. Methyl bromide, formaldehyde, and glutaraldehyde are the only soil treatment options that have been demonstrated at full-scale to effectively inactivate Bacillus spores. Soil sterilization modalities with high efficacy at bench-scale include wet and dry heat, metam sodium, chlorine dioxide gas, and activated sodium persulfate. Simple oxidants such as chlorine bleach are ineffective in sterilizing soil.

Dynamically expressed genes provide candidate viability biomarkers in a model coccidian

Eimeria parasites cause enteric disease in livestock and the closely related Cyclosporacayetanensis causes human disease. Oocysts of these coccidian parasites undergo maturation (sporulation) before becoming infectious. Here, we assessed transcription in maturing oocysts of Eimeria acervulina, a widespread chicken parasite, predicted gene functions, and determined which of these genes also occur in C. cayetanensis. RNA-Sequencing yielded ~2 billion paired-end reads, 92% of which mapped to the E. acervulina genome. The ~6,900 annotated genes underwent temporally-coordinated patterns of gene expression. Fifty-three genes each contributed >1,000 transcripts per million (TPM) throughout the study interval, including cation-transporting ATPases, an oocyst wall protein, a palmitoyltransferase, membrane proteins, and hypothetical proteins. These genes were enriched for 285 gene ontology (GO) terms and 13 genes were ascribed to 17 KEGG pathways, defining housekeeping processes and functions important throughout sporulation. Expression differed in mature and immature oocysts for 40% (2,928) of all genes; of these, nearly two-thirds (1,843) increased their expression over time. Eight genes expressed most in immature oocysts, encoding proteins promoting oocyst maturation and development, were assigned to 37 GO terms and 5 KEGG pathways. Fifty-six genes underwent significant upregulation in mature oocysts, each contributing at least 1,000 TPM. Of these, 40 were annotated by 215 GO assignments and 9 were associated with 18 KEGG pathways, encoding products involved in respiration, carbon fixation, energy utilization, invasion, motility, and stress and detoxification responses. Sporulation orchestrates coordinated changes in the expression of many genes, most especially those governing metabolic activity. Establishing the long-term fate of these transcripts in sporulated oocysts and in senescent and deceased oocysts will further elucidate the biology of coccidian development, and may provide tools to assay infectiousness of parasite cohorts. Moreover, because many of these genes have homologues in C. cayetanensis, they may prove useful as biomarkers for risk.

Effectiveness of poultry litter amendments on bacterial survival and Eimeria oocyst sporulation

AIM

Broilers' optimum performance in response to their genetic potential depends on litter environment which is ideal for bacterial survival and coccidian oocyst sporulation. An in vitro evaluation was conducted for the effectiveness of superphosphate, meta-bisulfide, and charcoal litter amendments in minimizing Escherichia coli O157:H7 and Salmonella Typhimurium survival, Eimeria oocyst count, and sporulation.

MATERIALS AND METHODS

Three groups of 16 litter trays were prepared and inoculated with E. coli O157:H7, S. Typhimurium, and Eimeria non-sporulated oocyst. A set of four trays in each group was designed for each one of the chemical amendments. A total of 720 litter samples were collected and examined for bacterial counts, Eimeria oocyst count, and sporulation during the experimental period (35 days).

RESULTS

Litter moisture and pH revealed a highly significant (p<0.001) reduction in all treated litter trays compared to control. Total bacterial count (TBC), total Enterobacteriaceae count, and S. Typhimurium count showed a highly significant (p<0.001) reduction in meta-bisulfide-treated trays compared to other amendments and positive control. Meanwhile, Eimeria oocyst count and sporulation revealed a highly significant (p<0.001) reduction in superphosphate, meta-bisulfide, and charcoal-treated trays, respectively. Temperature revealed a highly significant (p<0.001) weak positive correlation with pH of all inoculated trays, a highly significant (p<0.001) weak negative correlation with moisture percentage of E. coli O157:H7 and S. Typhimurium inoculated trays, and a highly significant (p<0.001) weak negative correlation with TBC. Meanwhile, relative humidity revealed significant (p≤0.005) weak positive correlation with moisture percentage of E. coli O157:H7 inoculated trays.

CONCLUSION

The study concluded that regular usage with periodical reapplication of litter amendments as meta-bisulfide or superphosphate in poultry farms is one of the indispensable managemental and preventive measures for minimizing bacterial survival and inhibiting Eimeria oocyst maturation and sporulation.

β-1,3-Glucan, Which Can Be Targeted by Drugs, Forms a Trabecular Scaffold in the Oocyst Walls of Toxoplasma and Eimeria

The walls of infectious pathogens, which are essential for transmission, pathogenesis, and diagnosis, contain sugar polymers that are defining structural features, e.g., β-1,3-glucan and chitin in fungi, chitin in Entamoeba cysts, β-1,3-GalNAc in Giardia cysts, and peptidoglycans in bacteria. The goal here was to determine in which of three walled forms of Toxoplasma gondii (oocyst, sporocyst, or tissue cyst) is β-1,3-glucan, the product of glucan synthases and glucan hydrolases predicted by whole-genome sequences of the parasite. The three most important discoveries were as follows. (i) β-1,3-glucan is present in oocyst walls of Toxoplasma and Eimeria (a chicken parasite that is a model for intestinal stages of Toxoplasma) but is absent from sporocyst and tissue cyst walls. (ii) Fibrils of β-1,3-glucan are part of a trabecular scaffold in the inner layer of the oocyst wall, which also includes a glucan hydrolase that has a novel glucan-binding domain. (iii) Echinocandins, which target the glucan synthase and kill fungi, arrest development of the Eimeria oocyst wall and prevent release of the parasites into the intestinal lumen. In summary, β-1,3-glucan, which can be targeted by drugs, is an important component of oocyst walls of Toxoplasma but is not a component of sporocyst and tissue cyst walls.

We show here that walls of Toxoplasma oocysts, the infectious stage shed by cats, contain β-1,3-glucan, a sugar polymer that is a major component of fungal walls. In contrast to fungi, β-1,3-glucan is part of a trabecular scaffold in the inner layer of the oocyst wall that is independent of the permeability barrier formed by the outer layer of the wall. While glucan synthase inhibitors kill fungi, these inhibitors arrest the development of the oocyst walls of Eimeria (an important chicken pathogen that is a surrogate for Toxoplasma) and block release of oocysts into the intestinal lumen. The absence of β-1,3-glucan in tissue cysts of Toxoplasma suggests that drugs targeted at the glucan synthase might be used to treat Eimeria in chickens but not to treat Toxoplasma in people.