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16 recordsLinked to original sources
PubMed1978

Leptotrichia buccalis hemagglutination in cell binding and salivary inhibition studies.

The characteristic hemagglutination (HA) of Leptotrichia buccalis was used for measuring its attachment to various human cells and for determining if saliva contained hemagglutination inhibition (HI) factors. The microbial strain utilized displayed the characteristic EM morphology of L. buccalis. Sonicated preparations of the organism were tested for HA activity before and after adsorption with human cells. Buccal epithelial cells, red blood cells (RBC), HeLa and embryonic kidney cells all bound the HA fragments of the organisms. The bacterial fragments on the cells could be observed by fluorescent antibody testing. The fragments were released from the cells used for adsorption with chelators and upon addition of CaCl2 the HA activity returned. Whole saliva displayed hemagglutination inhibition activity in a manner suggesting a binding site interaction. The similarity of the HA activity of F. nucleatum is discussed as are the relationships of cell binding to colonization of the organisms and immunopathology to host cells.

Adsorption↗
PubMed2025

Methods for Cas13a expression and purification for use in CRISPR diagnostics.

The threat of emerging infectious diseases (e.g., SARS-CoV-2 the RNA virus responsible for the COVID-19 pandemic) has highlighted the importance of accurate and rapid testing for screening, patient diagnosis, and effective treatment of infectious disease. Nucleic acid diagnostic tools such as qPCR are considered the gold standard, providing a sensitive, accurate, and robust method of detection. However, these conventional diagnostic platforms are resource intensive, limited in some applications, and are almost always confined to laboratory settings. With the increasing demand for low-cost, rapid, and accurate point-of-care diagnostics, CRISPR-based systems have emerged as powerful tools to augment detection capabilities. Of note is the potent RNA detection enzyme, Leptotrichia buccalis (Lbu) Cas13a, which is capable of rapid RNA detection in complex mixtures with or without pre-amplification. To support its wide-spread use, we describe a detailed method for the expression, purification, and validation of LbuCas13a for use in molecular diagnostics.

SARS-CoV-2↗
PubMed1976

Blastogenic response of human lymphocytes to oral bacterial antigens: characterization of bacterial sonicates.

Soluble sonicate supernatant preparations were made from Actinomyces viscosus (ATCC 19246), A. naeslundii (ATCC 12104), two strains of Veillonella alcalescens (strain HV-1 and a human oral isolate), Streptococcus sanguis (ATCC 10556), S. mutans (strain 6715-T2), Bacteroides melaninogenicus (strain K110), and Leptotrichia buccalis (isolated from human dental plaque). These supernatants were characterized with reference to their chemical and antigenic components and their biological activity determined by using in vitro lymphocyte blastogenesis as a measure of the host's cellular immune response. The sonicate supernatant of each bacterium contained protein, neutral sugars, methylpentose, and nucleic acids. Protein was the major component in all except L. buccalis, in which neutral sugars predominated. The antigenic components in each supernatant were detected by using rabbit antisera prepared against the whole bacteria and the sonicate supernatant. The supernatants showed a complex antigenic distribution on immunoelectrophoretic analysis. The supernatants were shown to be antigenic and not mitogenic in nature, since neither cord blood lymphocytes nor all adult lymphocytes were stimulated. The supernatant antigen preparations showed a reproducible, dose-dependent, and kinetic response in vitro, which was similar to that seen with the antigen preparation streptokinase-streptodornase.

Actinomyces↗
PubMed1976

Blastogenic response of human lymphocytes to oral bacterial antigens: comparison of individuals with periodontal disease to normal and edentulous subjects.

Cell-mediated immunity in humans to antigens derived from oral plaque bacteria was investigated by using the lymphocyte blastogenesis assay. Subjects with varying severities of periodontal disease including normal, gingivitis, periodontitis, and edentulous were compared. Mononuclear leukocytes were separated from peripheral blood and cultured with antigens prepared by sonication of Actinomyces viscosus (AV), Actinomyces naeslundii (AN), Veillonella alcalescens (VA), Leptotrichia buccalis (LB), Bacteroides melaninogenicus (BM), and homologous dental plaque (DP). The lymphocyte response of subjects with gingivitis or periodontitis was significantly greater than that of normal subjects to antigens of AV, AN, and DP, but did not differ from the response of edentulous subjects. Periodontitis subjects were significantly more reactive than edentulous and normal subjects in response to VA, LB, and BM. These findings suggest that the tested gram-negative bacteria and the host response they evoke are associated with advanced periodontal destruction.

Actinomyces↗
PubMed1977

Hemagglutinating activity of Fusobacterium nucleatum.

Gingival isolates of oral Fusobacterium nucleatum strains (gram-negative anaerobic fusiform bacilli) have shown the characteristic ability to hemagglutinate a variety of erythrocytes (RBC) of human and animal origin. Other members of the genus tested (F. necrophorus, F. varium, and F. mortiferum) displayed little if any ability to hemagglutinate RBC. The hemagglutination (HA) activity could be observed in the F. nucleatum strains with the whole cells and in most instances with sonicated preparations of the organisms. The HA activity was observed in cell wall preparations of the organism and appeared dependent upon a heat-labile protein component of the cell wall. In decreasing order, the RBC that would hemagglutinate with the smallest concentration of HA preparations were rabbit, monkey, human, sheep, horse, and ox. No differences in HA activity of the preparations with cells from the various human blood types were noted. Absorption of the HA preparation of one strain with human cells removed HA moiety was bound to the cells via a Ca2+ binding site interaction since ethylenediaminetetraacetic acid and ethylene glycol-bis-N,N'-tetraacetic acid inhibited binding, and HA could be reestablished by the addition of Ca2+ but not Mg2+. Rabbit antisera to the F. nucleatum strains inhibited HA activity when tested with the HA preparation in the standard test, whereas anti-Leptotrichia buccalis sera or normal rabbit sera had no effect. A tanned-cell passive HA test with rabbit anti-F. nucleatum sera displayed reactivity between the homologous strains but little reactivity with the other Fusobacterium species tested.

Animals↗
PubMed1979

Serologic reactions of oral gram negative anaerobic bacilli.

Serological reactions were performed using hyperimmune rabbit antisera and antigenic preparations of Leptotrichia buccalis, Fusobacterium fusiforme, and Fusobacterium polymorphum. All tests indicated that there was serologic cross reactivity between the two Fusobacterium species. No cross reactivity could be detected between the Fusobacterium species and L. buccalis. The findings suggest that F. fusiform and F. polymorphum are similar in their immunogenicity, and that the grouping of these two organisms as F. nucleatum may be justified.

Antigens, Bacterial↗
PubMed2025

Metagenomic characterization of oral microbiome signatures to predict upper gastrointestinal and pancreaticobiliary cancers: a case-control study.

BACKGROUND: This study investigated the oral microbiome signatures associated with upper gastrointestinal (GI) and pancreaticobiliary cancers. METHODS: Saliva samples from cancer patients and age- and sex-matched healthy controls were analyzed using 16S rRNA-targeted sequencing, followed by comprehensive bioinformatics analysis. RESULTS: Significant dissimilarities in microbial composition were observed between cancer patients and controls across esophageal cancer (EC), gastric cancer (GC), biliary tract cancer (BC), and pancreatic cancer (PC) groups (R2 = 0.067, = 0.075, = 0.068, and = 0.044; p = 0.001, = 0.001, = 0.002, and = 0.004, respectively). Additionally, the oral microbiome composition significantly differed by the four cancer sites (p = 0.001 for EC vs. GC, EC vs. BC, EC vs. PC, GC vs. BC, and GC vs. PC; p = 0.013 for BC vs. PC). We built oral metagenomic classifiers to predict cancer and selected specific microbial taxa with diagnostic properties. For EC, the classifier differentiated cancer patients and controls with good accuracy (area under the curve [AUC] = 0.791) and included three genera: Akkermansia, Escherichia-Shigella, and Subdoligranulum. For GC, the classifier exhibited high discriminative power (AUC = 0.961); it included five genera (Escherichia-Shigella, Gemella, Holdemanella, Actinomyces, and Stomatobaculum) and three species (Eubacterium sp. oral clone EI074, Ruminococcus sp. Marseille-P328, and Leptotrichia wadei F0279). However, microbial taxa with diagnostic features for BC and PC were not identified. CONCLUSIONS: These findings suggested that the oral microbiome composition may serve as an indicator of tumorigenesis in upper GI and pancreaticobiliary cancers. The development of oral metagenomic classifiers for EC and GC demonstrates the potential value of microbial biomarkers in cancer screening.

Humans↗
PubMed1979

Acute appendicitis and Bacteroides fragilis.

Bacteria belonging to the Bacteroides fragilis group (B. fragilis, B. ovatus, B. vulgatus, B. distasonis, B. thetaiotaomicron and B. uniformis) were cultured in quantities of less than or equal to 10(5) c.f.u./ml from the excised appendix from 30 patients. Twenty-two patients (group I) had an acute purulent appendicitis (three with perforation), four were classified as slightly inflamed cases (group 2) and four had a normal appendix (group 3). The B. fragilis group of bacteria dominated among the anaerobic isolates, but Bifidobacteria, Fusobacteri, Clostridium perfringens, Lactobacilli, Leptotrichia and Veillonella, in decreasing order, were isolated as well. Among isolates of aerobic bacteria, E. coli was most frequently isolated (26/30 patients). No other genus was isolated from more than four of the appendices. Serological investigations of the humoral antibody response to polysaccharide antigens from four of the Bacteroides species showed that a doubling of the titer, or more, in paired serum samples could be observed as follows: against B. fragilis 6/22 patients (group 1), 3/8 patients (groups 2 and 3). The corresponding figures for B. ovatus were 11/22 and 2/8, B. vulgatus 3/22 and 0/8 and B. distasonis 4/22 and 0/8. Sera from two patients with ruptured appendix, and B. fragilis cultivated, showed the highest titer increases against the B. fragilis antigen. The data from the bacteriological and immunological investigations make us conclude that (i) the B. fragilis group of bacteria is the most common anaerobic group of bacteria isolated from normal and diseased appendices, (ii) the mere isolation of B. fragilis, encapsulated or not, does not imply an etiological role in appendicitis since there was no obvious difference in titer increases against B. fragilis in sera from patients with or without an inflamed appendix, and (iii) high, and significant, titer increases against B. fragilis are seen in sera from patients with ruptured appendix.

Acute Disease↗