Pigmented-anaerobic bacteria associated with canine periodontitis

Use of Nonhuman Primates in Periodontal Disease Research: Contribution of the Caribbean Primate Research Center and Cayo Santiago Rhesus Colony

This review article provides a historical summary regarding the use, value, and validity of the nonhuman primate model of periodontal disease. The information provided cites results regarding the features of naturally occurring periodontitis in various nonhuman primate species, as well as the implementation of a model of experimental periodontitis. Clinical similarities to human disease are discussed, as well as the use of these models to document physiological and pathophysiological tissue changes in the periodontium related to the initiation and progression of the disease. Additionally, the use of these analytics in examination of the tissue characteristics of the disease, and the utility of nonhuman primates in testing and describing various therapeutic modalities are described. As periodontitis represents a disease of an oral microbiome dysbiosis, features of the altered microbiome in the disease in nonhuman primates are related to similar findings in the human condition. The review then provides a summary of the features of local and systemic host responses to a periodontal infection in an array of nonhuman primate species. This includes attributes of innate immunity, acute and chronic inflammation, and adaptive immune responses. Finally, extensive information is presented regarding the role of Macaca mulatta derived from the Cayo Santiago community in evaluating critical biologic details of disease initiation, progression, and resolution. This unique resource afforded the capacity to relate risk and expression of disease and traits of the responses to age, sex, and matriline derivation (e.g., heritability) of the animals. The Cayo Santiago colony continues to provide a critical preclinical model for assessment of molecular aspects of the disease process that can lead to both new targets for therapeutics and consideration of vaccine approaches to preventing and/or treating this global disease.

Fusobacterium nucleatum and Treponema denticola are robust biomarkers for gingivitis and periodontitis in small dogs

Introduction

Periodontal disease is one of the most common oral diseases in dogs and humans. It starts with gingivitis, a reversible condition, and progresses to an irreversible condition, periodontitis. Unlike humans, the etiology of periodontal disease in dogs has not been widely studied. Many studies suggest that bacteria strongly implicated in human periodontal disease might also play a role in canine periodontal disease. In contrast to studies examining only the prevalence of bacteria, a recent study analyzed 336 gingival crevicular fluid (GCF) samples in dogs to evaluate the prevalence of 11 putative periodontopathic bacteria and the correlation and association of bacterial numbers individually and in combination with periodontal disease stages. Results showed that Treponema denticola (Td) was a strong prognostic biomarker for periodontitis in dogs. However, a limitation of this study was that samples were grouped according to the periodontal status of the target tooth only, without assessment of the overall oral health. Furthermore, the findings of this study revealed a need for validation in a larger sample size.

Materials and methods

This study ensured that the overall oral health assessment of dogs under 20 kg matched with sampled groups, thus eliminating the influence of environmental factors on the results. Furthermore, 1,054 GCF samples were analyzed using quantitative real-time polymerase chain reaction (qPCR) for 12 bacteria, including the same 11 putative periodontopathic bacteria [Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Td, Fusobacterium nucleatum (Fn), Prevotella nigrescens (Pn), Prevotella intermedia (Pi), Parvimonas micra (Pm), Eubacterium nodatum (En), Campylobacter rectus (Cr), and Eikenella corrodens (Ec)] and Porphyromonas gulae (P. gulae), suspected to be a major causative agent of periodontitis in dogs in some statistical evaluatioins.

Results

Interestingly, the present study found that Fn was strongly associated with gingivitis and reconfirmed a strong association between Td and periodontitis (irreversible periodontal disease). However, Aa showed no relevance, and P. gulae was not significantly associated with periodontal disease in dogs in this study.

Conclusion

These findings suggest that Fn and Td would be robust biomarkers for the severity of periodontal disease in small dogs.

Saliva Malondialdehyde Concentration of Dogs With and Without Periodontal Disease

The study investigated whether malondialdehyde (MDA), a biomarker for oxidative stress, can be used as a viable parameter in dog saliva for the diagnosis or early detection of periodontal disease (PD). Saliva MDA concentrations were measured preoperatively in dogs diagnosed with PD during dental prophylaxis and compared with those of dentally healthy dogs. 35 dogs were included in the study. The average MDA concentration was 270 ng/ml (range 27-633) in the dogs without PD (n = 10) and 183 (36-833) ng/ml (ng/ml) in the dogs with PD (n = 25). The maximum MDA concentration in the study group (PD ≥1) was 833 ng/ml, which was significantly higher than in the study group (PD = 0) (p<0.05). The study showed that salivary MDA concentrations could not distinguish between healthy dogs and those with PD.

Canine Pyometra: A Short Review of Current Advances

Pyometra, characterized by the accumulation of purulent exudate in the uterus, is the most prevalent reproductive disease in canines. While the disease often begins with mild local symptoms, it can escalate into peritonitis, sepsis, and multi-organ dysfunction, thereby posing a significant threat to life. Despite the high incidence and recognized significance of canine pyometra, gaps persist in our understanding of its epidemiology, etiology, and pathogenesis. Recent studies have, however, broadened our comprehension of this disease, shedding light on potential new infection sources, etiologies, and the application of clinical predictive biomarkers and new therapeutic protocols. This study aimed to review the current understanding of canine pyometra, with particular emphasis on the latest research concerning its etiology and epidemiology. Furthermore, it addressed key research questions and proposed directions for future investigations into various facets of canine pyometra.

A mixed infection involving Bacteroides denticanum, Lactobacillus salivarius, and Streptococcus anginosus as causative agents of abscess around a pharyngo-esophageal anastomosis and acute vertebral osteomyelitis: Identification by ribosomal RNA sequencing of bacterial isolates

"Bacteroides denticanum" is an anaerobic, non-spore-forming, gram-negative bacterium with a rod morphology typical of canine, ovine, and macropod oral flora. There is only one report of bloodstream infection caused by "B. denticanum" from a dog bite in human. Here, we report a case with no history of animal contact who developed an abscess caused by "B. denticanum" around a pharyngo-esophageal anastomosis after undergoing balloon dilatation procedure for stenosis following laryngectomy. The patient was a 73-year-old man with laryngeal cancer, esophageal cancer, hyperuricemia, dyslipidemia, and hypertension with a 4-week history of cervical pain, sore throat, and fever. Computed tomography showed fluid collection on the posterior pharyngeal wall. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) identified Bacteroides pyogenes, Lactobacillus salivarius, and Streptococcus anginosus from abscess aspiration. 16S ribosomal RNA sequencing re-identified the Bacteroides species as "B. denticanum". T2-weighted magnetic resonance images showed a high signal intensity adjacent to the anterior vertebral body of C3-C7. The diagnosis was peripharyngeal esophageal anastomotic abscess and acute vertebral osteomyelitis caused by "B. denticanum", L. salivarius, and S. anginosus. The patient was treated with sulbactam ampicillin intravenously for 14 days and then switched to oral amoxicillin with clavulanic acid for 6 weeks. To our knowledge, this is the first report of a human infection caused by "B. denticanum" without a history of animal contact. Despite remarkable advancements facilitated by MALDI-TOF MS in microbiological diagnosis, the accurate identification of novel, emerging, or uncommon microorganisms and comprehending their pathogenicity, suitable therapy, and follow up necessitate sophisticated molecular approaches.

Erythritol inhibits the growth of periodontal-disease-associated bacteria isolated from canine oral cavity

Periodontal disease (PD) is the most common oral disease that is caused by infection with periodontal-disease-associated bacteria (PDAB) such as Porphyromonas gulae and Porphyromonas macacae in dogs as well as in humans. Unlike humans, most dogs do not follow daily oral hygiene routine, and this results in many dogs being affected by PD. Thus, to prevent PD, it is important to control PDAB. Xylitol is a sugar alcohol that inhibits the growth of oral bacteria in humans. However, xylitol is poisonous to dogs and can lead to hypoglycemia and hepatic failure. Herein, we show the inhibitory effect of erythritol, a sugar alcohol that can be used safely in dogs, on the growth of PDAB isolated from dogs with PD. Oral bacteria were isolated from the oral cavities of dogs with PD, and the distribution of PDAB was evaluated. Interestingly, Porphyromonas gingivalis, a bacterium typically responsible for PD in humans, was not isolated from dog samples. The bacteriostatic effect of erythritol supplementation was investigated on isolated PDAB in vitro. Our results show that erythritol exert bacteriostatic effects on PDAB comparable to xylitol. Thus, application of erythritol can be suggested to control PDAB in dogs in the future.

The Relationship Between Periodontal Infection and Systemic and Distant Organ Disease in Dogs

Infection in the mouth causes systemic and distant organ changes in dogs. This article summarizes the information available. Reported changes include an increase in liver-generated acute-phase proteins in response to the infectious insult to the body and evidence of microscopic changes in renal, hepatic, and cardiac tissues. Treatment of periodontal infection results in a decrease in the acute-phase protein concentration, which supports the hypothesis that a cause-and-effect relationship exists between periodontal infection and distant organ changes.

Oral cancer in non-smoker non-drinker patients. Could comparative pet oncology help to understand risk factors and pathogenesis?

During the last decades there has been a progressive increase in proportion of incidence of oral cancer not related to a known etiologic factor, such as the so-called "oral cancer in young", a relevant tumor in non-smoker non-drinker (NSND) patients. The topic is matter of long standing debate, and adequate study models to analyze this entity are lacking. Spontaneous oral cancer in companion animals such as dogs and cats, presents more clinical and biological similarities with the human oral cancer than any other animal model. In our review we analyze how the study of spontaneous oral cancer in common pets can prospectively prove to be of double usefulness in unraveling the question about the origin of oral cancer in NSND patients, allowing both the analysis of environmental and behavioral risk factors, and the study of how carcinogenic viruses, chronic inflammation, and changes in immunity can influence pre-tumoral and tumoral microenvironment.

Microbiota populations in supragingival plaque, subgingival plaque, and saliva habitats of adult dogs

Background

Oral diseases are common in dogs, with microbiota playing a prominent role in the disease process. Oral cavity habitats harbor unique microbiota populations that have relevance to health and disease. Despite their importance, the canine oral cavity microbial habitats have been poorly studied. The objectives of this study were to (1) characterize the oral microbiota of different habitats of dogs and (2) correlate oral health scores with bacterial taxa and identify what sites may be good options for understanding the role of microbiota in oral diseases. We used next-generation sequencing to characterize the salivary (SAL), subgingival (SUB), and supragingival (SUP) microbial habitats of 26 healthy adult female Beagle dogs (4.0 ± 1.2 year old) and identify taxa associated with periodontal disease indices.

Results

Bacterial species richness was highest for SAL, moderate for SUB, and lowest for SUP samples (p < 0.001). Unweighted and weighted principal coordinates plots showed clustering by habitat, with SAL and SUP samples being the most different from one another. Bacteroidetes, Proteobacteria, Firmicutes, Fusobacteria, Actinobacteria, and Spirochaetes were the predominant phyla in all habitats. Paludibacter, Filifactor, Peptostreptococcus, Fusibacter, Anaerovorax, Fusobacterium, Leptotrichia, Desulfomicrobium, and TG5 were enriched in SUB samples, while Actinomyces, Corynebacterium, Leucobacter, Euzebya, Capnocytophaga, Bergeyella, Lautropia, Lampropedia, Desulfobulbus, Enhydrobacter, and Moraxella were enriched in SUP samples. Prevotella, SHD-231, Helcococcus, Treponema, and Acholeplasma were enriched in SAL samples. p-75-a5, Arcobacter, and Pasteurella were diminished in SUB samples. Porphyromonas, Peptococcus, Parvimonas, and Campylobacter were diminished in SUP samples, while Tannerella, Proteocalla, Schwartzia, and Neisseria were diminished in SAL samples. Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher oral health scores (worsened health) in plaque samples.

Conclusions

Our results demonstrate the differences that exist among canine salivary, subgingival plaque and supragingival plaque habitats. Salivary samples do not require sedation and are easy to collect, but do not accurately represent the plaque populations that are most important to oral disease. Plaque Actinomyces, Corynebacterium, Capnocytophaga, Leptotrichia, and Neisseria were associated with higher (worse) oral health scores. Future studies analyzing samples from progressive disease stages are needed to validate these results and understand the role of bacteria in periodontal disease development.

Subgingival microbiota of dogs with healthy gingiva or early periodontal disease from different geographical locations

BACKGROUND

Periodontal disease is the most common oral disease of dogs worldwide and results from a complex interplay between plaque bacteria, the host and environmental factors. Recent studies have enhanced our understanding of the associations between the plaque microbiota and canine periodontal disease. These studies, however, were limited in their geographical reach. Thus associations between the canine oral microbiota and geographical location were investigated by determining the composition of subgingival plaque samples from 587 dogs residing in the United Kingdom (UK), United States of America (USA), China and Thailand using 454-pyrosequencing.

RESULTS

After quality filtering 6,944,757 sequence reads were obtained and clustering of these at ≥98% sequence resulted in 280 operational taxonomic units (OTUs) following exclusion of rare OTUs (present at < 0.05% in all four countries). The subgingival plaque from dog populations located in the UK, USA, China and Thailand had a similar composition although the abundance of certain taxa varied significantly among geographical locations. Exploration of the effect of clinical status and age revealed a marked similarity among the bacteria associated with increased age and those associated with gingivitis: Young dogs and those with no gingivitis were dominated by taxa from the phyla Bacteroidetes and Proteobacteria whereas older dogs and those with moderate gingivitis were dominated by members of the Firmicutes. The plaque microbiota of small breed dogs was found to significantly differ to medium and large breeds and was dominated by species belonging to the Firmicutes.

CONCLUSIONS

The bacterial associations with health, gingivitis and periodontitis were conserved across dogs from the UK, USA, China and Thailand. These bacterial signatures of periodontal health and disease have potential as biomarkers for disease detection.

Effect of feeding a daily oral care chew on the composition of plaque microbiota in dogs

The objective of this study was to investigate the influence of daily feeding of an oral care chew on the composition of canine supragingival plaque microbiota. Twelve beagle dogs were recruited to the randomized cross-over study. The dogs were fed one of two dietary regimes, both consisting of a commercially available wet and dry diet mix, either with or without daily supplementation with an oral care chew. After each 28-day test phase, supragingival plaque samples were collected and processed via Illumina sequencing to determine the microbiota composition. A comparative analysis of bacterial species associated with health and periodontal disease, identified from prior clinical studies, revealed differences between the dietary regimes. Consumption of the daily oral care chew, resulted in a significant increase in proportion of 6 health associated taxa but only 3 disease associated taxa compared to no chew. In contrast, 8 disease and 1 health associated taxa showed increased proportions for no chew versus the oral care chew. Daily feeding of the oral care chew tested in this study has therefore been shown to increase the proportion of health associated bacteria, over bacteria associated with periodontal disease, in supragingival plaque compared to no chew. By influencing plaque microbiota towards a bias for health associated bacteria, feeding of the oral care chew provides a means to reduce the prevalence of bacterial species shown to be associated with periodontal disease in dogs.

Treatment of Porphyromonas gulae infection and downstream pathology in the aged dog by lysine-gingipain inhibitor COR388

COR388, a small-molecule lysine-gingipain inhibitor, is currently being investigated in a Phase 2/3 clinical trial for Alzheimer's disease (AD) with exploratory endpoints in periodontal disease. Gingipains are produced by two species of bacteria, Porphyromonas gingivalis and Porphyromonas gulae, typically associated with periodontal disease and systemic infections in humans and dogs, respectively. P. gulae infection in dogs is associated with periodontal disease, which provides a physiologically relevant model to investigate the pharmacology of COR388. In the current study, aged dogs with a natural oral infection of P. gulae and periodontal disease were treated with COR388 by oral administration for up to 90 days to assess lysine-gingipain target engagement and reduction of bacterial load and downstream pathology. In a 28-day dose-response study, COR388 inhibited the lysine-gingipain target and reduced P. gulae load in saliva, buccal cells, and gingival crevicular fluid. The lowest effective dose was continued for 90 days and was efficacious in continuous reduction of bacterial load and downstream periodontal disease pathology. In a separate histology study, dog brain tissue showed evidence of P. gulae DNA and neuronal lysine-gingipain, demonstrating that P. gulae infection is systemic and spreads beyond its oral reservoir, similar to recent observations of P. gingivalis in humans. Together, the pharmacokinetics and pharmacodynamics of COR388 lysine-gingipain inhibition, along with reduction of bacterial load and periodontal disease in naturally occurring P. gulae infection in the dog, support the use of COR388 in targeting lysine-gingipain and eliminating P. gingivalis infection in humans.

Long-term follow-up study after administration of a canine interferon-α preparation for feline gingivitis

Intraoral administration of canine interferon alpha (CaIFN-α) has been shown to reduce gingivitis in dogs, but has not been confirmed in cats. Therefore, in this study, a CaIFN-α preparation was used for feline gingivitis, and the degree and duration of its effects were examined. Cats were divided into two groups: one was administered CaIFN-α, and the other was not. They were observed up to 12 months. It was suggested that CaIFN-α have a reducing effect on gingivitis and halitosis for a certain period although may not on plaque or calculus. In addition, the duration of the CaIFN-α gingivitis-reducing effect was suggested to be about three months. The CaIFN-α preparation is considered to be a useful treatment for oral hygiene control.

Identification of uncultured bacteria from abscesses of exotic pet animals using broad-range nested 16S rRNA polymerase chain reaction and Sanger sequencing

Background:

The Sanger sequencing technique has been questioned and challenged by advanced high-throughput sequencing approaches. Sanger sequencing seems to be an obsolete technology. However, there are still research problems that could be answered using the Sanger sequencing technology. Fastidious obligate anaerobic bacteria are mostly associated with abscesses in animals. These bacteria are difficult to isolate from abscesses and are frequently excluded due to the bias of conventional bacterial culturing.

Aim:

This study demonstrated the usefulness of a broad-range polymerase chain reaction (PCR) with Sanger sequencing to identify the majority population of bacteria in abscesses from exotic pet animals.

Materials and Methods:

This study performed a pilot investigation of abscesses from 20 clinical cases (17 rabbits, 2 hedgehogs, and 1 sugar glider) using standard culture methods for both aerobes and anaerobes and broad-range nested PCR targeting the 16S rRNA gene followed by the Sanger sequencing technique.

Results:

The standard culture and PCR techniques detected bacteria in 9 and 17 of 20 samples, respectively. From the 17 sequencings of the 16S rRNA, 10 PCR products were found to be closely related with obligate anaerobes including Bacteroides spp., Fusobacterium spp., Prevotella spp. Phylogenetic analysis using the rpoB gene revealed that the species for the Bacteroides was thetaiotaomicron and for the Fusobacterium was varium and nucleatum. However, the amplification of the rpoB gene for the Prevotella spp. was unsuccessful. Correlations between the standard culture and PCR techniques were found in 9 (6 positive and 3 negative samples) of 20 samples. Eleven samples were discordant between the standard culture and PCR techniques which were composed of eight samples negative by culture but positive by PCR and three samples had different bacteria by the culture and PCR techniques.

Conclusion:

According to this study, broad-range PCR combined with Sanger sequencing might be useful for the detection of dominant anaerobic bacteria in abscesses that were overlooked based on conventional bacterial culture.

Purification and characterization of a fimbrial protein from Porphyromonas salivosa ATCC 49407

Periodontal disease is a significant problem in companion animals such as dogs and cats. However, there is little information available about fimbriae association of periodontal disease in companion animals. In this study, we have purified and characterized a fimbriae from Porphyromonas salivosa ATCC 49407. The molecular mass of this protein was approximately 60-kDa, as estimated by SDS-PAGE. Immunogold electron microscopy revealed that anti-60-kDa fimbrial serum bound to fimbria on the cell surface of P. salivosa ATCC 49407. However, fimbriae of P. gingivalis and P. gulae were not labeled with the same antibody. Immunoelectron-microscopic studies and immunoblot analysis revealed that antigenicity and molecular weight were distinct from previously reported Porphyromonas fimbrial proteins. The amino acid sequence of the N-terminal 15 residues of the 60-kDa fimbrillin protein revealed only 3 of 15 residues identical to other Porphyromonas species fimbrillin proteins. Thus, the N-terminal amino acid sequence of the 60-kDa fimbrillin protein of P. salivosa clearly differed from previously reported fimbrillin proteins. The level of adherence of the P. salivosa was 1.81%. It was confirmed that P. salivosa can adheres to human cells. These results suggest that the 60-kDa fimbriae of P. salivosa ATCC 49407 is a new type of fimbria and may have an important factor in the adherence host cells. We suggest that the surface structure of P. salivosa may have a role in the colonization of this organism in periodontal pockets in companion animals.

Efficacy of virginiamycin for the control of periodontal disease in calves

ABSTRACT: Periodontal diseases are multifactorial infectious processes caused by complexes of microorganisms, with damage to health, production, and animal welfare. The aim of the present study was to evaluate the efficacy of virginiamycin in the prevention and control of two early forms of periodontal disease: gingivitis and necrotizing gingivitis. Ten weaned calves, aged four to six months, were permanently kept in a single lot under the same rotational grazing regime in a newly reformed area of Panicum maximum. Five of the calves were orally administered 340mg of virginiamycin (Virginiamycin Group) daily for a period of 18 weeks, while the remaining five calves (Control Group) remained under the same food management but did not receive virginiamycin. During this period, animals underwent 18 weekly evaluations regarding periodontal health, with monitoring and recording of clinical parameters of the eight deciduous incisor teeth on the labial and lingual faces. At approximately two-week intervals, nine collections of subgingival sulcus material from five sites of the four right incisor teeth of each animal were performed and subjected to microbiological evaluation using polymerase chain reaction with primers of 25 microorganisms considered potentially pathogenic. After 1440 periodontal clinical evaluations of incisor teeth of the 10 calves, a total of 395 episodes of gingivitis were recorded, of which 267 occurred in the Control Group and 128 in the Virginiamycin Group. Similarly, 89 episodes of necrotizing gingivitis were recorded; 58 in the Control Group and 31 in the Virginiamycin Group. Comparison of between-group means found significant differences for teeth with gingivitis and necrotizing gingivitis (t test; p<0.05). The total number of teeth with gingivitis (p<0.01) and necrotizing gingivitis (p<0.01) in Control Group was significantly higher than that of gingivitis (p<0.01) and necrotizing gingivitis (p<0.05) in the Virginiamycin Group. There was a positive correlation between total occurrence of gingivitis and necrotizing gingivitis in the Virginiamycin Group by Pearson’s test. Virginiamycin had a protective effect on treated animals compared with the Control Group (OR = 0.36: CI (95%) = 0.27-0.43). In the Control Group, Actinomyces israelli (4.74%), domain Archaea (1.58%), Eikenella corrodens (1.05%), Fusobacterium nucleatum (27.37%), class Mollicutes (5.26%); Porphyromonas endodontalis(5.26%); Porphyromonas gulae(0.53%), Prevotella buccae (6.32%), Prevotella loescheii (3.68%), Prevotella nigrescens (8.42%), Prevotella oralis (1.58%), Tannerella forsythia (0.53%), and Treponema denticola (4.21%) were detected at healthy sites, and gingivitis or necrotizing gingivitis samples. In the Virginiamycin Group, A. israelli (3.41%), domain Archaea (0.98%), F. nucleatum (9.27%), class Mollicutes(4.39%), P. endodontalis (4.39%), P. gulae (0.49%), P. buccae (8.29%), P. loescheii (6.83%), P. nigrescens (15.61%), P. oralis (1.46%), Selenomonas sputigena (0.49%), T. forsythia (0.49%), and T. denticola (2.44%) were detected. In conclusion, virginiamycin administered at a dosage of 340mg/animal/day significantly reduced the occurrence of gingivitis and necrotizing gingivitis in cattle maintained on reformed pastures, and was revealed to have action against periodontal bacterial microbiota considered to be potentially pathogenic.

Effects of Passive Immunization by Anti-Gingipain IgY on the Oral Health of Cats Fed Kibble Diets

Porphyromonas gulae is one of the key microorganisms in biofilm dysbiosis that leads to periodontal disease, a prevalent disease in cats. Gingipains are proteases secreted that promote the disruption of cell adhesion and the differentiation of osteoclasts. The use of anti-gingipain immunoglobulin Y (IgY-GP) has emerged as a promising alternative to conventional prevention and treatment methods. The aim of this study was to evaluate the efficacy of IgY-GP on different parameters related to oral health in cats. Twenty adult mixed-breed cats were divided into 2 groups of 10 cats fed with 2 extruded diets differing only by coating. The control group received a coating of 4 g/kg of powdered egg and the test group received a coating of 4 g/kg of IgY-GP. The experiment followed a crossover design with 2 periods, each lasting 40 days with a washout period of 30 days. The evaluated parameters were plaque, calculus, gingivitis index, and percentage of Porphyromonas gingivalis of the oral cavity (%PG-OC) at baseline and after 40 days of diet consumption. All cats remained healthy throughout the study and no adverse reactions or side effects were observed. After 40 days of IgY-GP consumption, the plaque index was significantly lower compared to the baseline ( P = .0133). There were no significant changes in calculus index, gingivitis index, and %PG-OC between groups after 40 days ( P > .05). The consumption of IgY-GP reduces plaque accumulation, which may lead to an improvement in the oral health of adult cats.

The occurrence of Treponema spp. in gingival plaque from dogs with varying degree of periodontal disease

Periodontal disease is common in dogs and is initiated by gingival plaque composed of several hundred bacterial species. Some of these species have specifically been pointed out as potential periodontal pathogens, such as Treponema spp. Treponema spp. are difficult to culture and therefore the majority have been detected by culture-independent methods, such as PCR (Polymerase Chain Reaction). This leaves many Treponema spp. uncharacterized and unnamed. In this study, treponemes were investigated in gingival plaque from dogs with varying degree of periodontal disease with the aim to describe their occurrence and diversity in dogs. The methods used were culture, phase-contrast microscopy, PCR targeting the 16SrRNA-tRNA^Ile intergenic spacer region (ISR2), sequencing of the ISR2 and phylogenetic analysis. Treponema spp. were detected in samples from 10 out of 11 dogs and isolates were obtained from six dogs. Both healthy and periodontitis affected dogs were Treponema positive. Phylogenetic analysis, based on ISR2 sequences, revealed a large diversity of treponemes in the study population that were found to be distributed mainly in two groups, corresponding to the human oral treponeme phylogroups II (Treponema denticola) and IV (Treponema maltophilum) genetic groups. They were generally more distantly related to other treponemes in these groups. Treponemes from dogs with periodontitis and dogs with mild gingivitis without periodontitis did not differ in any obvious way. The results indicate that several phylotypes of oral treponemes are common in dogs regardless of periodontal status.

Elevated EGF Levels in the Blood Serum of Dogs with Periodontal Diseases and Oral Tumours

BACKGROUND/AIM

Paradontopathy and neoplasms of the oral cavity represent one of the greatest challenges in human and animal dentistry. EGF plays a key role in maintaining the integrity and proper rate of cell proliferation in normal oral epithelium. The aim of the present study was to study serum levels of EGF in dogs diagnosed with periodontal diseases and oral cavity tumours.

MATERIALS AND METHODS

The samples comprised of cancerous tissue sections and serum obtained from dogs of various breeds, aged between 5-13 years. Serum EGF concentrations were measured by an immunoenzymatic method.

RESULTS

The median for EGF concentration in serum of dogs suffered from severe periodontal diseases was greater when compared to the control group. EGF concentration in dogs with malignant tumours was significantly higher than in those with non-malignant growths. A positive correlation between EGF concentration and tumour size was also observed. EGF level in dogs diagnosed with benign tumours was comparable to the control group.

CONCLUSION

The blood serum level of EGF increases significantly in patients with malignant oral tumours and advanced periodontal disease. In malignant tumours, the high level of EGF correlates with the size and invasiveness of the neoplasm.

Porphyromonas gulae Activates Unprimed and Gamma Interferon-Primed Macrophages via the Pattern Recognition Receptors Toll-Like Receptor 2 (TLR2), TLR4, and NOD2

Porphyromonas gulae is an anaerobic, Gram-negative coccobacillus that has been associated with periodontal disease in companion animals. The aims of this study were to analyze the ligation of pattern recognition receptors by P. gulae and the subsequent activation of macrophages. Exposure of HEK cells transfected with Toll-like receptors (TLRs) or NOD-like receptors to P. gulae resulted in the ligation of TLR2, TLR4, and NOD2. The effects of this engagement of receptors were investigated by measuring the synthesis of nitric oxide (NO), CD86 expression, and inflammatory cytokine production by wild-type, TLR2^-/-, and TLR4^-/- macrophages. The addition of P. gulae to unprimed and gamma interferon (IFN-γ)-primed (M1 phenotype) macrophages significantly increased the surface expression of CD86, but only M1 macrophages produced nitric oxide. P. gulae-induced expression of CD86 on unprimed macrophages was dependent on both TLR2 and TLR4, but CD86 expression and NO production in M1 macrophages were only TLR2 dependent. P. gulae induced an increase in secretion of interleukin-1α (IL-1α), IL-1β, IL-6, IL-12p70, IL-13, tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein 1α (MIP-1α) by M1 macrophages compared to that by unprimed controls. Among these cytokines, secretion of IL-6 and TNF-α by M1 macrophages was dependent on either TLR2 or TLR4. Our data indicate that TLR2 and TLR4 are important for P. gulae activation of unprimed macrophages and that activation and effector functions induced in M1 macrophages by P. gulae are mainly dependent on TLR2. In conclusion, P. gulae induces a strong TLR2-dependent inflammatory M1 macrophage response which may be important in establishing the chronic inflammation associated with periodontal disease in companion animals.

Molecular-level evaluation of selected periodontal pathogens from subgingival regions in canines and humans with periodontal disease

Dogs commonly serve as a model for various human conditions, including periodontal diseases. The aim of this study was to identify the anaerobic bacteria that colonize the subgingival areas in dogs and humans by using rapid real-time polymerase chain reaction (RT-PCR)-based tests and to compare the results obtained in each species. Bacterial microflora evaluations, both quantitative and qualitative, were performed by applying ready-made tests on twelve dogs and twelve humans. Five samples were collected from each subject's deepest gingival pockets and joined to form a collective sample. The results of the study revealed interspecies similarities in the prevalences of Porphyromonas (P.) gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum. Red complex bacteria comprised the largest portion of the studied bacterial complexes in all study groups, with P. gingivalis being the most commonly isolated bacterium. The results show similarities in the prevalence of bacterial microflora in dogs and humans. Microbiological analysis of gingival pockets by using rapid real-time PCR-based tests in clinical practice, both veterinary and human, can facilitate the choice of appropriate pharmacological treatment and can provide a basis for subsequent verification of the treatment's effectiveness.

Pathogenicity and genetic profile of oral Porphyromonas species from canine periodontitis

OBJECTIVE

In this study, the presence of the prtC and fimA genes involved in the pathogenicity of oral Porphyromonas spp. isolated from dogs with periodontitis and healthy, as well as their genetic diversity was investigated.

DESIGN

Thirty-two Beagle dogs, 24 with periodontitis and 8 healthy were evaluated. Subgingival samples from only one gingival site of both groups were collected. Bacteria grown in anaerobiosis were identified by RAPID ID 32A kits. From each strain the respective DNA was obtained and used to genotyping by conventional PCR and AP-PCR.

RESULTS

Dogs with periodontitis harbored 28 P. gulae, 2 P. creviocaricanis, 1 P. cangingivalis and 7 P. macacae; and from healthy dogs, 11 P. gulae and 5 P. circumdentaria. In P. gulae isolated from periodontal dogs the gene prtC was observed in 19 (67.85%) and in 7 (63.63%) from healthy dogs. P. gulae strains from periodontal dogs harbored either the gene fimA I or fimA II; while strains from healthy dogs harbored the gene fimA I, fimA II, fimA III or fimA IV, as well as 1 P. circumdentaria the gene fimA II. By AP-PCR strains were grouped in different clusters suggesting heterogeneity of these microorganisms.

CONCLUSIONS

The results presented herein inform that Porphyromonas spp. isolated from dogs with and without periodontitis harbored the prtC and fimA genes and it could be a role in the establishment of the infectious process.

Black-pigmented anaerobic bacteria associated with ovine periodontitis

Periodontitis is a polymicrobial infectious disease that causes occlusion change, tooth loss, difficulty in rumination, and premature culling of animals. This study aimed to detect species of the genera Porphyromonas and Prevotella present in the periodontal pocket of sheep with lesions deeper than 5mm (n=14) and in the gingival sulcus of animals considered periodontally healthy (n=20). The presence of microorganisms was evaluated by polymerase chain reaction (PCR) using specific primers for Porphyromonas asaccharolytica, Porphyromonas endodontalis, Porphyromonas gingivalis, Porphyromonas gulae, Prevotella buccae, Prevotella intermedia, Prevotella loescheii, Prevotella melaninogenica, Prevotella nigrescens, Prevotella oralis, and Prevotella tannerae. Prevalence and risk analysis were performed using Student's t-test and Spearman's correlation. Among the Prevotella and Porphyromonas species detected in the periodontal lesions of sheep, P. melaninogenica (85.7%), P. buccae (64.3%), P. gingivalis (50%), and P. endodontalis (50%) were most prevalent. P. gingivalis (15%) and P. oralis (10%) prevailed in the gingival sulcus. P. gulae and P. tannerae were not detected in the 34 samples studied. Data evaluation by t-test verified that occurrence of P. asaccharolytica, P. endodontalis, P. gingivalis, P. buccae, P. intermedia, P. melalinogenica, and P. nigrescens correlated with sheep periodontitis. The findings of this study will be an important contribution to research on pathogenesis of sheep periodontitis and development of its control measures.

Porphyromonas gulae Has Virulence and Immunological Characteristics Similar to Those of the Human Periodontal Pathogen Porphyromonas gingivalis

Periodontitis is a significant problem in companion animals, and yet little is known about the disease-associated microbiota. A major virulence factor for the human periodontal pathogen Porphyromonas gingivalis is the lysyl- and arginyl-specific proteolytic activity of the gingipains. We screened several Porphyromonas species isolated from companion animals-P. asaccharolytica, P. circumdentaria, P. endodontalis, P. levii, P. gulae, P. macacae, P. catoniae, and P. salivosa-for Lys- and Arg-specific proteolytic activity and compared the epithelial and macrophage responses and induction of alveolar bone resorption of the protease active species to that of Porphyromonas gingivalis Only P. gulae exhibited Lys-and Arg-specific proteolytic activity. The genes encoding the gingipains (RgpA/B and Kgp) were identified in the P. gulae strain ATCC 51700 and all publicly available 12 draft genomes of P. gulae strains. P. gulae ATCC 51700 induced levels of alveolar bone resorption in an animal model of periodontitis similar to those in P. gingivalis W50 and exhibited a higher capacity for autoaggregation and binding to oral epithelial cells with induction of apoptosis. Macrophages (RAW 264.7) were found to phagocytose P. gulae ATCC 51700 and the fimbriated P. gingivalis ATCC 33277 at similar levels. In response to P. gulae ATCC 51700, macrophages secreted higher levels of cytokines than those induced by P. gingivalis ATCC 33277 but lower than those induced by P. gingivalis W50, except for the interleukin-6 response. Our results indicate that P. gulae exhibits virulence characteristics similar to those of the human periodontal pathogen P. gingivalis and therefore may play a key role in the development of periodontitis in companion animals.

Evaluation of Subgingival Bacteria in the Dog and Susceptibility to Commonly Used Antibiotics

The aim of the present investigation was to evaluate the subgingival aerobic and anaerobic flora of 13 dogs with periodontal disease and the susceptibility of these bacteria to antibiotics currently approved in Italy for treatment of canine infections. Of the anaerobic bacteria, Bacteroides fragilis was most frequently isolated, followed by Peptostreptococcus + Porphyromonas gingivalis and Prevotella intermedia. Of the aerobic bacteria, α-hemolytic Streptococcus was most frequently isolated, often associated with Escherichia coli or Pasteurella multocida. Resistance of anaerobic and aerobic bacteria to various antibiotics was generally high. Anaerobic bacteria appeared to be susceptible to amoxicillin + clavulanic acid, doxycycline, and erythromycin; aerobic bacteria appeared to be susceptible to amoxicillin + clavulanic acid, erythromycin, gentamycin, and sulfa-trimethoprim. Bacteroides fragilis was resistant to all of the antibiotics tested. The emerging worldwide problem of bacterial resistance to antibiotics resulting from overuse and misuse of antibiotics is discussed.

Porphyromonas bronchialis sp. nov. Isolated from Intraoperative Bronchial Fluids of a Patient with Non-Small Cell Lung Cancer

Porphyromonas strains, including Porphyromonas-like strains, have been isolated from oral and various other systemic infections. The characterization of such strains is a crucial issue, because such information contributes to both the taxonomy of anaerobic bacteria and the clinical aspects of infectious diseases. We previously isolated four Porphyromonas-like strains from intraoperative bronchial fluids of a patient with non-small cell lung cancer. This study aimed to characterize the genetic, biochemical and chemotaxonomic aspects of these isolates. Each strain only grew under anaerobic conditions and their colony morphology was convex, 0.1-1.0 mm in diameter, light gray, and slightly glistening colony, with no black or brown pigmentation on blood agar plates after five-day incubation. The pigmentation was helpful to differentiate the isolates from other Porphyromonas, as most of Porphyromonas species show the pigmentation. In the 16S rRNA gene phylogenetic analysis (98% sequence identity of isolates indicates the same species), the four isolates were closely related to one another (99.7-100.0%), but not related to Porphyromonas (P.) catoniae, the closest species (96.9%). In addition, the DNA-DNA hybridization data revealed less than 16% similarity values between a representative isolate and the P. catoniae, indicating that the strains were genetically independent. Biochemically, the isolates could be differentiated from closely related species, i.e., P. catoniae, P. gingivalis, P. gulae, and P. pogonae, with trypsin activity (negative only in the isolates) and leucine arylamidase activity (positive only in the isolates). We therefore propose a new species to include these isolates: Porphyromonas bronchialis sp. nov.

Presence of Porphyromonas and Prevotella species in the oral microflora of cattle with periodontitis

Abstratc: Bovine periodontitis is a progressive purulent infectious process associated with the presence of strictly and facultative anaerobic subgingival biofilm and epidemiologically related to soil management in large geographic areas of Brazil. This study aimed to detect species of the genera Porphyromonas and Prevotella, which occurr in periodontal pockets of cattle with lesions deeper than 5mm (n=26) and in gingival sulcus of animals considered periodontally healthy (n=25). Presence of the microorganisms was evaluated by independent-culture medium diagnostic method, using polymerase chain reaction (PCR) with specific primers of Porphyromonas asaccharolytica, P. endodontalis, P. gingivalis, P. gulae, Prevotella buccae, P. intermedia, P. loescheii, P. melaninogenica, P. nigrescens, P. oralis and P. tannerae. The species P. endodontalis (80.7%), P. melaninogenica (73.1%) and P. intermedia (61.5%) were the most predominant in samples of cattle with periodontitis. Regarding non-injured gingival sulcus of cattle, P. endodontalis (40%) and P. loeschei (40%) prevailed. Porphyromonas gingivalis, P. gulae and Prevotella tannerae were not detected in the 51 samples studied. Data evaluation by T test, enabled to verify that ocorrence of Porphyromonas asaccharolytica (p=0.000003), P. endodontalis (p=0.0023), Prevotella buccae (p=0.0017), P. intermedia (p=0.0020), P. melaninogenica (p=0.00006) and P. oralis (p=0.0028) is correlated with bovine periodontitis.

A longitudinal assessment of changes in bacterial community composition associated with the development of periodontal disease in dogs

Periodontal disease is the most widespread oral disease in dogs. Whilst the involvement of bacteria in the aetiology of periodontitis is well established the role of individual species and their complex interactions with the host is not well understood. The objective of this research was therefore to perform a longitudinal study in dogs to identify the changes that occur in subgingival bacterial communities during the transition from mild gingivitis to the early stages of periodontitis (<25% attachment loss). Subgingival plaque samples were collected from individual teeth of 52 miniature schnauzer dogs every six weeks for up to 60 weeks. The microbial composition of plaque samples was determined using 454-pyrosequencing of the 16S rDNA. A group of aerobic Gram negative species, including Bergeyella zoohelcum COT-186, Moraxella sp. COT-017, Pasteurellaceae sp. COT-080, and Neisseria shayeganii COT-090 decreased in proportion as teeth progressed to mild periodontitis. In contrast, there was less evidence that increases in the proportion of individual species were associated with the onset of periodontitis, although a number of species (particularly members of the Firmicutes) became more abundant as gingivitis severity increased. There were small increases in Shannon diversity, suggesting that plaque community membership remains relatively stable but that bacterial proportions change during progression into periodontitis. This is the first study to demonstrate the temporal dynamics of the canine oral microbiota; it showed that periodontitis results from a microbial succession predominantly characterised by a reduction of previously abundant, health associated taxa.

Porphyromonas gulae 41-kDa fimbriae induced osteoclast differentiation and cytokine production

Porphyromonas gulae is considered to be associated with canine periodontitis. We have previously reported that the P. gulae American Type Culture Collection (ATCC) 51700 comprised 41-kDa fimbriae. The purpose of the present study was to demonstrate the roles of 41-kDa fimbrial protein in periodontal disease. In this study, we examined the involvement of the 41-kDa fimbrial protein in osteoclast differentiation and cytokine production in murine macrophages. Furthermore, alveolar bone resorption induced by P. gulae infection in rats was evaluated. To estimate osteoclast differentiation, bone marrow cells and MC3T3-G2/PA6 cells were cultured with or without the 41-kDa fimbrial protein for 7 days. BALB/c mouse peritoneal macrophages were stimulated with the 41-kDa fimbrial protein, and the levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α production were determined by enzyme-linked immunosorbent assay. Osteoclast differentiation was significantly enhanced by treatment with the 41-kDa fimbrial protein in a dose-dependent manner. The total area of pits formed on the dentine slices with osteoclasts incubated with the 41-kDa fimbrial protein was significantly greater than that of the control. The purified 41-kDa fimbrial protein induced IL-1β and TNF-α production in BALB/c mouse peritoneal macrophages after 6 hr of incubation in a dose-dependent manner. The bone loss level in rats infected with P. gulae was significantly higher than that of the sham-infected rats. These results suggest that P. gulae 41-kDa fimbriae play important roles in the pathogenesis of periodontal disease.

Evaluation of a topical gel containing a novel combination of essential oils and antioxidants for reducing oral malodor in dogs

OBJECTIVE

To evaluate the effectiveness of a topically applied gel containing essential oils (menthol and thymol) and polyphenolic antioxidants (phloretin and ferulic acid) for reducing halitosis in dogs.

ANIMALS

20 dogs.

PROCEDURES

A blinded crossover clinical trial was conducted. Dogs received a dental cleaning and examination (periodontal examination including periodontal probing and assessments of plaque, calculus, and gingivitis). Owners then applied a gel (active or placebo) to oral soft tissues twice daily for a 4-week period. Teeth of the dogs were cleaned again, and owners applied the other gel for a 4-week period. Clinicians scored halitosis immediately after the initial cleaning and at 4 and 8 weeks, and owners scored halitosis weekly.

RESULTS

Halitosis assessment by clinicians revealed that both groups had improvement in halitosis scores. Two dogs were removed because of owner noncompliance. In the active-to-placebo group (n = 9), halitosis was significantly reduced during application of the active gel but increased during application of the placebo. Seven of 9 owners reported increased halitosis when treatment was changed from the active gel to the placebo. In the placebo-to-active group (n = 9), halitosis decreased during application of the placebo and continued to decrease during application of the active gel. Seven of 9 owners reported a decrease in halitosis with the active gel.

CONCLUSIONS AND CLINICAL RELEVANCE

An oral topically applied gel with essential oils and polyphenolic antioxidants applied daily after an initial professional dental cleaning decreased oral malodor in dogs.

Periodontal disease associated with red complex bacteria in dogs

OBJECTIVE

Red complex bacteria (Treponema denticola, Tannerella forsythia and Porphyromonas gingivalis) play a major role in the aetiology of periodontal disease in humans. This study was designed to evaluate the association of such bacteria with periodontal disease in dogs.

METHODS

Seventy-three subgingival samples taken from dogs ranging from 2 months to 12 years (median age 4 years) were tested for red complex bacteria using a polymerase chain reaction assay.

RESULTS

Thirty-six of 73 (49 · 3%) dogs were found to be positive for T. forsythia and P. gingivalis. Dogs with gingivitis or periodontitis were more likely to be infected with T. forsythia and P. gingivalis [odds ratio (OR) 5 · 4 (confidence interval (CI) 1 · 9-15 · 6), P = 0 · 002] than healthy animals. Only 3 (4 · 1%) of 73 samples were positive for red complex bacteria, but the association with periodontal disease was not significant.

CONCLUSION AND CLINICAL RELEVANCE

The results indicate that involvement of red complex bacteria in periodontal disease in dogs is similar to that observed in humans. Only the concurrent presence of T. forsythia and P. gingivalis were correlated to periodontal disease in dogs in this study.

Comparative analysis of gingival tissue antigen presentation pathways in ageing and periodontitis

AIM

Gingival tissues of periodontitis lesions contribute to local elevations in mediators, including both specific T cell and antibody immune responses to oral bacterial antigens. Thus, antigen processing and presentation activities must exist in these tissues to link antigen-presenting cells with adaptive immunity. We hypothesized that alterations in the transcriptome of antigen processing and presentation genes occur in ageing gingival tissues and that periodontitis enhances these differences reflecting tissues less capable of immune resistance to oral pathogens.

MATERIALS AND METHODS

Rhesus monkeys (n = 34) from 3 to 23 years of age were examined. A buccal gingival sample from healthy or periodontitis sites was obtained, total RNA isolated, and microarray analysis was used to describe the transcriptome.

RESULTS

The results demonstrated increased transcription of genes related to the MHC class II and negative regulation of NK cells with ageing in healthy gingival tissues. In contrast, both adult and ageing periodontitis tissues showed decreased transcription of genes for MHC class II antigens, coincident with up-regulation of MHC class I-associated genes.

CONCLUSION

These transcriptional changes suggest a response of healthy ageing tissues through the class II pathway (i.e. endocytosed antigens) and altered responses in periodontitis that could reflect host-associated self-antigens or targeting cytosolic intracellular microbial pathogens.

Isolation of Treponema and Tannerella spp. from equine odontoclastic tooth resorption and hypercementosis related periodontal disease

REASONS FOR PERFORMING STUDY

Red complex bacteria, i.e. Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia, are involved in the onset and progression of periodontal disease in man, yet seldom inhabit the oral cavity of healthy individuals. Periodontal disease is also encountered in horses, with equine odontoclastic tooth resorption and hypercementosis (EOTRH) constituting a particular form of disease. However, only little is known about the oral microbiome of healthy and periodontitis-affected equids.

OBJECTIVE

We aimed to test the hypothesis that red complex bacteria are also associated with EOTRH-related periodontal disease.

STUDY DESIGN

Controlled cross-sectional study.

METHODS

We screened DNA purified from crevicular fluid derived from 23 EOTRH-affected and 21 disease-free horses for the presence of Treponema spp., Tannerella spp. and Porphyromonas gingivalis DNA by polymerase chain reaction. Subsequently, amplified DNA was bidirectionally sequenced and identified via BLAST analysis.

RESULTS

Treponema and/or Tannerella DNA was detected in 100% of periodontitis-related samples and in 52.2% of DNA derived from healthy horses. Twenty-six amplicon sequences were 98-100% homologous to published bacterial sequences, which mostly corresponded to Treponema pectinovorum, oral Treponema clones JU025 and OMZ 840, and Tannerella forsythia. P. gingivalis DNA was only found in 3 EOTRH-related samples. Forty-three amplicon sequences revealed weaker homologies ranging between 80% and 97% to known Treponema or Tannerella strains, partly because of their heterogeneity, partly because they obviously represented so far unknown types.

CONCLUSIONS

This is the first report in which known and novel Treponema and Tannerella spp. were isolated in association with EOTRH-related periodontal disease.

Purification and characterization of a novel secondary fimbrial protein from Porphyromonas gulae

Background

Porphyromonas gulae are black-pigmented anaerobic bacteria isolated from the gingival sulcus of various animal hosts and are distinct from Porphyromonas gingivalis originating in humans. We previously reported the antigenic similarities of 41-kDa fimbriae between P. gulae ATCC 51700 and P. gingivalis ATCC 33277. In this study, to clarify the presence of another type of fimbriae of P. gulae, we have purified and characterized the secondary fimbrial protein from P. gulae ATCC 51700.

Methods

The secondary fimbrial protein was purified from P. gulae ATCC 51700 using an immunoaffinity column coupling with antibodies against the 41-kDa fimbrial protein. The expression of fimbriae on the cell surface of P. gulae ATCC 51700 was investigated by transmission electron microscopy. The N-terminal amino acid sequence was determined by an amino acid sequencer system.

Results

The molecular mass of this protein was approximately 53-kDa, as estimated by SDS-PAGE. The polyclonal antibodies against the 53-kDa protein did not react with the 41-kDa fimbrial protein of P. gulae ATCC 51700. Immunogold electron microscopy revealed that anti-53-kDa fimbrial serum bound to fimbria on the cell surface of P. gulae ATCC 51700. The amino acid sequence of the N-terminal 15 residues of the 53-kDa fimbrial protein showed only 1 of 15 residues identical to the 41-kDa fimbrial protein.

Conclusion

The 53-kDa fimbriae are different in molecular weight and antigenicity from the 41-kDa fimbrial protein of P. gulae ATCC 51700. These results clearly suggest that the 41-kDa and the 53-kDa fimbriae are distinct types of fimbriae expressed simultaneously by this organism.

Effects of immunization with natural and recombinant lysine decarboxylase on canine gingivitis development

Periodontal disease, gingival inflammation (gingivitis) and periodontal attachment loss (periodontitis), causes tooth loss and susceptibility to chronic inflammation. Professionally scaling and cleaning the teeth regularly controls the disease, but is expensive in companion animals. Eikenella corrodens is common in canine oral cavities where it is a source of lysine decarboxylase (LDC). In human dental biofilms (plaques), LDC converts lysine to cadaverine and impairs the gingival epithelial barrier to bacteria. LDC vaccination may therefore retard gingivitis development. Year-old beagle dogs provided blood samples, and had weight and clinical measurements (biofilm and gingivitis) recorded. After scaling and cleaning, two dogs were immunized subcutaneously with 0.2mg native LDC from E. corrodens and 2 sets of four dogs with 0.2mg recombinant LDC purified from Escherichia coli. A third set of 4 dogs was immunized intranasally. Rehydragel(®), Emulsigen(®), Polygen™ or Carbigen™ were used as adjuvant. Four additional pairs of dogs were sham-immunized with each adjuvant alone (controls). Immunizations were repeated twice, 3 weeks apart, and clinical measurements were obtained after another 2 weeks, when the teeth were scaled and cleaned again. Tooth brushing was then stopped and the diet was changed from hard to soft chow. Clinical measurements were repeated after 1, 2, 3, 4, 6 and 8 weeks. Compared with sham-immunized dogs, gingivitis was reduced over all 8 weeks of soft diet after subcutaneous immunization with native LDC, or after intranasal immunization with recombinant LDC in Carbigen™, but for only 6 of the 8 weeks after subcutaneous immunization with recombinant LDC in Emulsigen(®) (repeated measures ANOVA). Subcutaneous vaccination induced a strong serum IgG antibody response that decreased during the soft diet period, whereas intranasal immunization induced a weak serum IgA antibody response that did not decrease. Immunization with recombinant LDC may provide protection from gingivitis if procedures are optimized.

PG0026 is the C-terminal signal peptidase of a novel secretion system of Porphyromonas gingivalis

Protein substrates of a novel secretion system of Porphyromonas gingivalis contain a conserved C-terminal domain (CTD) of ∼70-80 amino acid residues that is essential for their secretion and attachment to the cell surface. The CTD itself has not been detected in mature substrates, suggesting that it may be removed by a novel signal peptidase. More than 10 proteins have been shown to be essential for the proper functioning of the secretion system, and one of these, PG0026, is a predicted cysteine proteinase that also contains a CTD, suggesting that it may be a secreted component of the secretion system and a candidate for being the CTD signal peptidase. A PG0026 deletion mutant was constructed along with a PG0026C690A targeted mutant encoding an altered catalytic Cys residue. Analysis of clarified culture fluid fractions by SDS-PAGE and mass spectrometry revealed that the CTD was released intact into the surrounding medium in the wild type strain, but not in the PG0026 mutant strains. Western blot experiments revealed that the maturation of a model substrate was stalled at the CTD-removal step specifically in the PG0026 mutants, and whole cell ELISA experiments demonstrated partial secretion of substrates to the cell surface. The CTD was also shown to be accessible at the cell surface in the PG0026 mutants, suggesting that the CTD was secreted but could not be cleaved. The data indicate that PG0026 is responsible for the cleavage of the CTD signal after substrates are secreted across the OM.

The canine oral microbiome

Determining the bacterial composition of the canine oral microbiome is of interest for two primary reasons. First, while the human oral microbiome has been well studied using molecular techniques, the oral microbiomes of other mammals have not been studied in equal depth using culture independent methods. This study allows a comparison of the number of bacterial taxa, based on 16S rRNA-gene sequence comparison, shared between humans and dogs, two divergent mammalian species. Second, canine oral bacteria are of interest to veterinary and human medical communities for understanding their roles in health and infectious diseases. The bacteria involved are mostly unnamed and not linked by 16S rRNA-gene sequence identity to a taxonomic scheme. This manuscript describes the analysis of 5,958 16S rRNA-gene sequences from 65 clone libraries. Full length 16S rRNA reference sequences have been obtained for 353 canine bacterial taxa, which were placed in 14 bacterial phyla, 23 classes, 37 orders, 66 families, and 148 genera. Eighty percent of the taxa are currently unnamed. The bacterial taxa identified in dogs are markedly different from those of humans with only 16.4% of oral taxa are shared between dogs and humans based on a 98.5% 16S rRNA sequence similarity cutoff. This indicates that there is a large divergence in the bacteria comprising the oral microbiomes of divergent mammalian species. The historic practice of identifying animal associated bacteria based on phenotypic similarities to human bacteria is generally invalid. This report describes the diversity of the canine oral microbiome and provides a provisional 16S rRNA based taxonomic scheme for naming and identifying unnamed canine bacterial taxa.