Antigenic diversity in flagellar epitopes among Bacillus piliformis isolates

Implications of infectious agents on results of animal experiments

Report of the Working Group on Hygiene of the Gesellschaft für Versuchstierkunde–Society for Laboratory Animal Science (GV-SOLAS)

GV-SOLAS Working Group on Hygiene: Werner Nicklas (Chairman), Felix R. Homberger, Brunhilde Illgen-Wilcke, Karin Jacobi, Volker Kraft, Ivo Kunstyr, Michael Mähler, Herbert Meyer & Gabi Pohlmeyer-Esch

Risk factors for Clostridium piliforme infection in foals

OBJECTIVE

To determine risk factors for Clostridium piliforme infection in neonatal foals on a Thoroughbred breeding farm in California.

DESIGN

Case-control and retrospective cohort studies.

ANIMALS

322 neonatal Thoroughbred foals either born on the study farm or born elsewhere but traveled to the farm with their dam during the 1998, 1999, and 2000 breeding seasons.

PROCEDURE

Mare and foal records from 1998, 1999, and 2000 were examined, using case-control design methods to determine variables associated with increased risk of C. piliforme infection in foals. Important risk factors identified in the case-control study were then reevaluated by use of a retrospective cohort design, using data from all neonatal foals present on the farm during the 3-year study period.

RESULTS

Foals born between March 13 and April 13 were 7.2 times as likely to develop C. piliforme infection as were those born at any other time of the foaling season. Foals of nonresident (visiting) mares were 3.4 times as likely to develop disease as were foals born to mares that were permanent residents of the study farm. Foals of mares < 6 years of age were 2.9 times as likely to develop disease as were foals born to older mares.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this research can be used to better understand the epidemiologic factors of C. piliforme infection in horses. High-risk foals can be closely monitored to aid in early diagnosis and treatment, resulting in the best possible clinical outcome for affected individuals.

Acanthamoeba castellanii: characterization of an adhesin molecule

Acanthamoeba castellanii is a free-living protozoan that causes keratitis in humans and has been associated with pneumonia and granulomatous amebic encephalitis in dogs, sheep, and other species. Adherence of the Acanthamoeba to epithelial cells is critical to the pathogenesis of this disease. In this study, several mouse monoclonal antibodies (MAb) generated to whole Acanthamoeba trophozoites identified surface membrane epitopes by ELISA and IFA. Nine antibodies inhibited adherence of [(35)S]-methionine-labeled Acanthamoeba trophozoites to hamster corneal epithelial cells by 27-90%. Sodium periodate treatment, but not proteinase K digestion, of whole Acanthamoeba destroyed epitopes recognized by adherence-inhibiting antibodies such as MAb 7H6, suggesting that the adherence epitopes are carbohydrates. Other antibodies, MAb 2A8 for example, recognized surface membrane peptide epitopes that were proteinase K sensitive and sodium periodate resistant. Purified MAb 2A8 was used in an antigen-capture ELISA with peroxidase-labeled MAb 7H6 and demonstrated that the carbohydrate adhesion molecule was linked to the peptide recognized by MAb 2A8. Both MAbs 7H6 and 2A8 recognized a >207-kDa band on a Western blot of eluant from a MAb 2A8 immunoaffinity column, confirming that MAb 7H6 and MAb 2A8 recognize different epitopes on the same adherence molecule. MAbs 7H6 and 2A8 also identified the adhesion molecule in soluble Acanthamoeba membrane preparations and MAb 2A8 immunoaffinity column eluant by ELISA and Western blot. Neither of these antibodies were inhibited from binding to whole trophozoites nor membrane extracts by mannose or mannan in competitive binding assays. When our Acanthamoeba membrane preparations were electrophoresed and immunoblotted with alpha-d-mannosylated-biotin albumin, no bands were recognized in the >207 kDa range by our adherence-associated antibodies. These results suggest that the Acanthamoeba adhesin is not identical to the mannose binding protein of Acanthamoeba but rather is a distinct surface membrane glycoprotein.

Bacillus piliformis infection (Tyzzer's disease) in a patient infected with HIV-1: confirmation with 16S ribosomal RNA sequence analysis

Bacillus piliformis is a long, rod-shaped bacterium that has never been grown in cell-free medium and whose taxonomic classification is uncertain. B. piliformis is the causative agent of Tyzzer's disease, which is frequently reported in laboratory, wild, and domesticated animals. The spectrum and severity of this disease is wide in animals. Although many infections are rapidly fatal, subclinical infections are also common. To date, there have been no reports of B. piliformis infection in human beings, although elevated antibody levels have been reported in pregnant women. We describe the first case of human B. piliformis infection, in a man with HIV-1 infection and chronic, localized, crusted verrucous lesions. The diagnosis was confirmed by ribosomal RNA sequencing. The spectrum of organisms leading to infection and the spectrum of diseases caused by these organisms continue to expand, as new infections are identified and as patients with HIV-1 live longer with more severe immune suppression. The extreme difficulty in culturing B. piliformis and the lack of clinical and histopathologic experience with this organism in human beings mean that B. piliformis is potentially another infectious agent to be considered in human beings. Also, when an infectious organism is a strong clinical consideration, silver stains may be of use when results of routine bacterial staining are negative.

Seroanalysis of Tyzzer's disease in horses: implications that multiple strains can infect Equidae

A monoclonal antibody based competitive inhibition assay was used to detect antibodies in horse sera to purified flagellar antigens from distinct Clostridium piliforme isolates. Sequential absorption of hyperimmune rat serum to C. piliforme isolate E (horse-origin isolate), a positive C. piliforme-immune horse serum, and other suspected immune horse sera with unrelated bacteria or C. piliforme isolates E or isolate R1 (rat-origin isolate) alone demonstrated the specificity of this assay for C. piliforme. This specificity was associated with the inhibition of monoclonal antibody binding to C. piliforme flagella, rather than to C. piliforme somatic antigens, by horse immunoglobulins partially purified from serum. Thirty seven of 162 horse sera possessed large amounts of antibody to the flagella of C. piliforme isolate E and 23 of the 162 had large amounts of antibody to the flagella of C. piliforme isolate R1; 9 of the sera possessed large amounts of antibody to both flagellar antigens. Absorption of these sera with isolate E or R1 demonstrated that antibody reactivity to the 2 C. piliforme isolates was isolate-specific and not due to antibody cross-reactive with both isolates. These results suggest that infection of horses with C. piliforme may be relatively common; and that they are susceptible to at least 2 distinct strains.