@article{suyemoto_hamrick_spears_horton_washington_havell_borst_orndorff_2013, title={Extrauterine Listeriosis in the gravid mouse influences embryonic growth and development}, volume={8}, number={8}, journal={PLoS One}, author={Suyemoto, M. M. and Hamrick, T. S. and Spears, P. A. and Horton, J. R. and Washington, I. M. and Havell, E. A. and Borst, L. B. and Orndorff, P. E.}, year={2013} } @article{spears_suyemoto_hamrick_wolf_havell_orndorff_2011, title={In Vitro Properties of a Listeria monocytogenes Bacteriophage-Resistant Mutant Predict Its Efficacy as a Live Oral Vaccine Strain}, volume={79}, ISSN={["1098-5522"]}, DOI={10.1128/iai.05700-11}, abstractNote={ABSTRACTAListeria monocytogenesglcVmutation precludes the binding of certain listerial phages and produces a profound attenuation characterized by the absence of detectable mutants in the livers and spleens of orally inoculated mice.Invitro, we found that the mutant formed plaques on mouse enterocyte monolayers as efficiently as the parent but the plaques formed were smaller. Intracellular growth rate determinations and examination of infected enterocytes by light and fluorescence microscopy established that the mutant was impaired not in intracellular growth rate but in cell-to-cell spreading. Because this property is shared by other immunogenic mutants (e.g.,actAmutants), ourglcVmutant was tested for vaccine efficacy. Oral immunization with the mutant and subsequent oral challenge (22 days postvaccination) with the parent revealed a ca. 10,000-fold increase in protection afforded by the mutant compared to sham-vaccinated controls. TheglcVmutant did not stimulate innate immunity under the dose and route employed for vaccination, and an infectivity index time course experiment revealed pronounced mutant persistence in Peyer's patches. The immunogenicity of theglcVmutant compared to an isogenicactAmutant reference strain was next tested in an experiment with a challenge given 52 days postvaccination. Both mutant strains showed scant vital organ infectivity and high levels of protection similar to those seen using theglcVmutant in the 22-day postvaccination challenge. Our results indicate that oral administration of a profoundly attenuated listerial mutant can safely elicit solid protective immunity.}, number={12}, journal={INFECTION AND IMMUNITY}, author={Spears, Patricia A. and Suyemoto, M. Mitsu and Hamrick, Terri S. and Wolf, Rebecca L. and Havell, Edward A. and Orndorff, Paul E.}, year={2011}, month={Dec}, pages={5001–5009} } @article{spears_suyemoto_palermo_horton_hamrick_havell_orndorff_2008, title={A Listeria monocytogenes mutant defective in bacteriophage attachment is attenuated in orally inoculated mice and impaired in enterocyte intracellular growth}, volume={76}, ISSN={["0019-9567"]}, DOI={10.1128/IAI.00283-08}, abstractNote={ABSTRACT A Listeria monocytogenes bacteriophage was used to identify a phage-resistant Tn 917 insertion mutant of the mouse-virulent listerial strain F6214-1. The mutant was attenuated when it was inoculated orally into female A/J mice and failed to replicate efficiently in cultured mouse enterocytes. Phage binding studies indicated that the mutant had a cell surface alteration that precluded phage attachment. All phenotypes associated with the mutation could be complemented in trans by a single open reading frame (ORF) that corresponded to the ORF interrupted by the Tn 917 insertion. The complementation effected was, in all cases, at a level indistinguishable from that of the parent. The Tn 917 insertion interrupted a gene that is predicted to encode a group 2 glycosyl transferase (provisionally designated glcV ). A similar glcV gene is present in Listeria welshimeri and Listeria innocua and in some serotypes of L. monocytogenes . We speculate that the loss of the glcV product results in a defective phage receptor and that this alteration coincidentally influences a feature of the normal host-pathogen interaction required for virulence. Interestingly, the glcV lesion, while preventing phage attachment, did not alter the mutant's ability to bind to cultured mouse enterocyte monolayers. Rather, the mutation appeared to alter a subsequent step in intracellular replication measured by a reduction in plaque-forming efficiency and plaque size. In vivo, the mutant was undetectable in the liver and spleen 48 h after oral inoculation. The mutation is significant in part because it is one of the few that produce attenuation when the mutant is delivered orally. }, number={9}, journal={INFECTION AND IMMUNITY}, author={Spears, Patricia A. and Suyemoto, M. Mitsu and Palermo, Angela M. and Horton, John R. and Hamrick, Terri S. and Havell, Edward A. and Orndorff, Paul E.}, year={2008}, month={Sep}, pages={4046–4054} } @misc{orndorff_hamrick_smoak_havell_2006, title={Host and bacterial factors in listeriosis pathogenesis}, volume={114}, ISSN={["1873-2542"]}, DOI={10.1016/j.vetmic.2005.12.003}, abstractNote={Members of the Genus Listeria are ubiquitous environmental saprophytic microorganisms. If ingested they can cause a severe disseminated disease (listeriosis) that has a high mortality rate, the highest of any food-borne pathogen, even with antibiotic therapy. Central to the high mortality rate is the hallmark characteristic of the microorganism to grow intracellularly. The presence of listeriae in food processing plants has resulted in many outbreaks of human disease and large scale recalls of processed foods. Despite the ubiquity of the microorganism, the actual disease rate (those animals showing disease signs over those exposed) is quite low and disease is almost always associated with an underlying predisposition (pregnancy being the most common in otherwise normal individuals). There are many features of the pathogenesis of listeriosis that have remained mysterious despite the extensive use of the microorganism in the study of cell-mediated immunity and intracellular growth. Informational advances such as the sequence of the mouse and listerial genomes, and technical advances such as the discovery of listeria-susceptible mouse strains, may renew interest in the study of the natural pathogenesis of the disease. This may be further facilitated by studies that employ the natural inoculation route and mimic common predisposing conditions witnessed in victims of natural outbreaks.}, number={1-2}, journal={VETERINARY MICROBIOLOGY}, author={Orndorff, PE and Hamrick, TS and Smoak, IW and Havell, EA}, year={2006}, month={Apr}, pages={1–15} } @article{harris_spears_havell_hamrick_horton_orndorff_2001, title={Characterization of Escherichia coli type 1 pilus mutants with altered binding specificities}, volume={183}, ISSN={["0021-9193"]}, DOI={10.1128/JB.183.13.4099-4102.2001}, abstractNote={ABSTRACT PCR mutagenesis and a unique enrichment scheme were used to obtain two mutants, each with a single lesion in fimH , the chromosomal gene that encodes the adhesin protein (FimH) of Escherichia coli type 1 pili. These mutants were noteworthy in part because both were altered in the normal range of cell types bound by FimH. One mutation altered an amino acid at a site previously shown to be involved in temperature-dependent binding, and the other altered an amino acid lining the predicted FimH binding pocket. }, number={13}, journal={JOURNAL OF BACTERIOLOGY}, author={Harris, SL and Spears, PA and Havell, EA and Hamrick, TS and Horton, JR and Orndorff, PE}, year={2001}, month={Jul}, pages={4099–4102} } @article{hamrick_harris_spears_havell_horton_russell_orndorff_2000, title={Genetic characterization of Escherichia coli type 1 pilus adhesin mutants and identification of a novel binding phenotype}, volume={182}, ISSN={["0021-9193"]}, DOI={10.1128/JB.182.14.4012-4021.2000}, abstractNote={ABSTRACT Five Escherichia coli type 1 pilus mutants that had point mutations in fimH , the gene encoding the type 1 pilus adhesin FimH, were characterized. FimH is a minor component of type 1 pili that is required for the pili to bind and agglutinate guinea pig erythrocytes in a mannose-inhibitable manner. Point mutations were located by DNA sequencing and deletion mapping. All mutations mapped within the signal sequence or in the first 28% of the predicted mature protein. All mutations were missense mutations except for one, a frameshift lesion that was predicted to cause the loss of approximately 60% of the mature FimH protein. Bacterial agglutination tests with polyclonal antiserum raised to a LacZ-FimH fusion protein failed to confirm that parental amounts of FimH cross-reacting material were expressed in four of the five mutants. The remaining mutant, a temperature-sensitive (ts) fimH mutant that agglutinated guinea pig erythrocytes after growth at 31°C but not at 42°C, reacted with antiserum at both temperatures in a manner similar to the parent. Consequently, this mutant was chosen for further study. Temperature shift experiments revealed that new FimH biosynthesis was required for the phenotypic change. Guinea pig erythrocyte and mouse macrophage binding experiments using the ts mutant grown at the restrictive and permissive temperatures revealed that whereas erythrocyte binding was reduced to a level comparable to that of a fimH insertion mutant at the restrictive temperature, mouse peritoneal macrophages were bound with parental efficiency at both the permissive and restrictive temperatures. Also, macrophage binding by the ts mutant was insensitive to mannose inhibition after growth at 42°C but sensitive after growth at 31°C. The ts mutant thus binds macrophages with one receptor specificity at 31°C and another at 42°C. }, number={14}, journal={JOURNAL OF BACTERIOLOGY}, author={Hamrick, TS and Harris, SL and Spears, PA and Havell, EA and Horton, JR and Russell, PW and Orndorff, PE}, year={2000}, month={Jul}, pages={4012–4021} } @article{hamrick_havell_horton_orndorff_2000, title={Host and bacterial factors involved in the innate ability of mouse macrophages to eliminate internalized unopsonized Escherichia coli}, volume={68}, ISSN={["0019-9567"]}, DOI={10.1128/IAI.68.1.125-132.2000}, abstractNote={ABSTRACTIn an effort to better understand genetic and cellular factors that influence innate immunity, we examined host and bacterial factors involved in the nonopsonic phagocytosis and killing ofEscherichia coliK-12 by mouse macrophages. Unelicited (resident) peritoneal macrophages from five different mouse strains, BALB/c, C57BL/6, CD-1, C3H/HeJ, and C3H/HeN, were employed. Additional macrophage populations were obtained from CD-1 mice (bone marrow-derived macrophages). Also, for BALB/c and C57BL/6 mice, peritoneal macrophages elicited with either thioglycolate or proteose peptone, bone marrow-derived macrophages, and macrophage-like cell lines derived from the two strains were employed. TwoE. coliK-12 strains that differed specifically in their abilities to produce type 1 pili containing the adhesive protein FimH were examined. The parameters used to assess macrophage bacteriocidal activity were (i) the killing of internalized (gentamicin-protected)E. coliduring the approximately 4-h assay and (ii) the initial rate at which internalizedE. coliwere eliminated. Data on these parameters allowed the following conclusions: (i) unelicited or proteose peptone-elicited peritoneal macrophages were significantly better at eliminating internalized bacteria than thioglycolate-elicited peritoneal macrophages, bone marrow-derived macrophages, or macrophage cell lines; (ii) the host genetic background had no significant effect upon the ability of unelicited peritoneal macrophages to killE. coli(even though the mouse strains differ widely in their in vivo susceptibilities to bacterial infection); and (iii) the FimH phenotype had no significant effect uponE. colisurvival once the bacterium was inside a macrophage. Additionally, there was no correlation between the bacteriocidal effectiveness of a macrophage population and the number of bacteria bound per macrophage. However, macrophage populations that were the least bacteriocidal tended to bind higher ratios of FimH+to FimH−E. coli. The effect of gamma interferon, fetal calf serum, and the recombination proficiency ofE. coliwere examined as factors predicted to influence intracellular bacterial killing. These had no effect upon the rate ofE. colielimination by unelicited peritoneal macrophages.}, number={1}, journal={INFECTION AND IMMUNITY}, author={Hamrick, TS and Havell, EA and Horton, JR and Orndorff, PE}, year={2000}, month={Jan}, pages={125–132} }