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PubMed1994

Replacement of glycoprotein B gene in the herpes simplex virus type 1 strain ANGpath DNA by that originating from nonpathogenic strain KOS reduces the pathogenicity of recombinant virus.

Herpes simplex virus type-1 (HSV-1) strain ANGpath and its recombinants, in which the 8.1 kbp BamHI G restriction fragment (0.345-0.399) containing the glycoprotein B (gBpath) gene (UL27) or its subfragments-coding either for cytoplasmic or surface domains of gB-had been replaced with the corresponding fragments from nonpathogenic KOS virus DNA (gBKOS), were tested for their pathogenicity for DBA/2 mice and rabbits. The recombinant ANGpath/B6KOS prepared by transferring the 2.7 kbp SstI-SstI subfragment (0.351-0.368) of the BamHI GKOS fragment still had the original sequence of ANGpath DNA coding for the syn3 marker in the cytoplasmic domain of gB and was pathogenic for mice as well as for rabbits. Virological and immunohistological studies in DBA/2 mice infected with the latter pathogenic recombinant and with ANGpath showed the presence of infectious virus and viral antigen at inoculation site (epidermis, subcutaneous connective tissue and striated muscle in the area of right lip), in homolateral trigeminal nerve and ganglion, brain stem, midbrain, thalamic and hypothalamic nuclei. In contrast, nonpathogenic recombinants ANGpath/syn+B6KOS (prepared by transferring the whole BamHI GKOS fragment) and ANGpath/syn+KOS (prepared by transferring the 0.8 kbp BamHI-SstI subfragment of the BamHI GKOS fragment) showed limited haematogenous and neural spread, but no evidence of replication in CNS; thus, their behaviour resembled that of the wild type strain KOS. The recombinant ANGpath/syn+KOS, which was not pathogenic for mice, still remained pathogenic for rabbits, a phenomenon indicating the presence of an additional locus in the gB molecule participating on virulence. Sequencing the 1478 bp SstI-SstI subfragment of the BamHI G(path) fragment (nt 53,348-54,826 of UL segment) showed the presence of at least 3 mutations as compared to the KOS sequence, from which the change of cytosine to thymine at nt 54,251 altered the codon for arginine to that for histidine (amino acid 515) in the gB polypeptide chain.

Animals↗
PubMed1993

Comparative pathogenicity study of Leptospira interrogans serovar pomona strains.

The comparative pathogenicity study of two Leptospira interrogans serovar pomona strains isolated from pig herds of different epizootiological status is reported. Using monoclonal antibodies (Mabs), the isolates were identified as Leptospira interrogans serovar pomona. The results obtained for the reference strain of L. pomona were identical with those of the two isolates, with the exception of monoclonal serum designated 61-7, which gave a 1:30 titre with the reference strain. In a pig herd comprising 1,000 sows, strain XVIII caused abortion in 300 animals. In the hamster pathogenicity test, this strain killed the hamsters on postinoculation (PI) days 5 or 6. The pathogen was reisolated from their organs. Strain XV did not cause abortion in a herd of 600 sows; it only elicited seroconversion in a proportion of the animals (26 out of 274 blood samples were positive, corresponding to a seropositivity rate of 9.5%). This strain did not kill the hamsters and could be demonstrated from their organs neither by isolation nor by histological examination. The blood serum of two pregnant sows infected with strain XVIII contained high titres of antibodies (1:1,600 and 1:3,200) already on PI day 10. The first urine sample of these animals, taken on PI day 10, also contained large numbers of leptospires. The pathogen was reisolated from urine samples taken at 10-day intervals and from the kidneys of the slaughtered sows. One of the two infected sows delivered four non-viable and a viable piglet. From the kidneys of the non-viable piglets, leptospires were demonstrated by histological examination. In contrast, none of the four pregnant sows inoculated with strain XV aborted. The sows did not produce antibodies detectable by the microscopic agglutination test (MAT). The pathogen could not be isolated from urine samples and from kidney samples taken from the sows at slaughter. Histological demonstration of leptospires from the sows' kidneys also failed.

Animals↗
PubMed1993

[Analysis of pathogenicity of Entamoeba histolytica by polymerase chain reaction].

DNA from five isolates of Entamoeba histolytica were examined for their pathogenicity by polymerase chain reaction. Three isolates SH-3,SH-6,SH-8 were isolated from patients with acute amoebic dysentery, whereas SH-5 and SH-7 were isolated from asymptomatic cyst passers. Gel electrophoresis of PCR products showed that primers P11, P12 for pathogenic strains could amplify genomic DNA extracted from SH-8, and primers P13, P14 for nonpathogenic strains could amplify genomic DNA extracted from SH-3,SH-5,SH-6 and SH-7. Furthermore, zymodeme analysis and the reactivity of McAb 4G6, which recognizes the 30 kDa antigen of pathogenic E. histolytica indicated that only SH-8 was pathogenic, while the others were nonpathogenic. The results of the genotypic analysis by PCR were in accord with the phenotypic properties. It is suggested that there are differences in genomic DNA between pathogenic and nonpathogenic strains. PCR is a highly sensitive and specific method for genomic DNA analysis of E. histolytica.

Animals↗
PubMed1994

T cell receptor alpha-chain repertoire of pathogenic autoantibody-inducing T cells in lupus mice.

The production of pathogenic anti-DNA autoantibodies in mice with lupus nephritis is dependent on special autoimmune Th cells that can also transfer the disease into preautoimmune mice. In previous work, these pathogenic Th cells were cloned and their TCR beta-chains were sequenced to reveal a recurrent motif of anionic residues in their CDR3 loops. Accordingly, approximately half of the Th clones were found to be specific for nucleosomal Ag that contain cationic residues. Herein, we analyzed the TCR alpha-chain repertoire of 15 of these pathogenic Th clones and found them to be heterogeneous, even among the nucleosome-specific Th clones. Most of these autoimmune TCR alpha-chains contained anionic residues in their CDR3 in addition to cationic residues. Therefore, these pathogenic Th clones of lupus probably recognize epitopes with mixed charge runs that are derived from autoantigens, such as histone-DNA complexes. Interestingly, the V alpha gene segments used by 10 of these Th clones derived from the (SWR x NZB)F1 lupus mice differed from previously reported sequences indicating that they were new members or alleles of the respective V alpha gene family. One of the Th clones used a gene from an entirely new murine V alpha gene family, identified here as V alpha 23, which consisted of approximately two members that were conserved among strains with different V alpha haplotypes. Knowledge of the primary structure of the TCR expressed by these pathogenic Th clones of lupus would help in the analysis of their antigenic specificities and also would be essential for studying their regulation in transgenic mice carrying these autoimmune TCR genes.

Amino Acid Sequence↗
PubMed1977

Behaviour of Salmonellae non-pathogenic for mice. I. Neutralization of their toxicities by induced antiprotein antibodies.

Groups of mice hyperimmunized with proteins from Salmonella strains which are not pathogens for mice (S. typhi o901, S. typhi Ty2, S. blockley, S. newport) resisted inoculation with concentrations of homologous and related heterologous liver bacteria, which killed all the controls in 20-48 hrs. The toxicity of the Salmonella tested was about 100-1000 times lower than that of the pathogenic S. typhimurium and concentrations of 10(8) or 10(9) bacteria (according to the strains used) were necessary to kill all the controls. In contrast to the period of incubation (2-12 days) required for S. typhimurium to kill all the controls and eventually some of the immunized mice, too, the killing with the human pathogenic Salmonella took place within 20-48 hrs. The toxicity of the big concentrations of bacteria needed to kill the controls was apparently neutralized by the antiprotein antibodies induced in the immunized mice. In no group of mice resisting inoculations with 1 x 10(8) or 1 x 10(9) of the homologous or heterologous tested Salmonellae protection could be obtained against infection with 1LD100 (1 x 10(6) of S. typhimurium. These results underline the specificity of host-parasite relations in infection and minimize the role attributed to the cellular mechanism, which is insufficient for protection against an infection if the pathogen tested is not specific for the host in experiment. In contrast to events in mice protected against the infection with S. typhimurium, and its related "in vivo", S. paratyphi B and S. paratyphi C, the antibodies initially present in the sera of the mice immunized with proteins from the human pathogens were no longer found 25 days after the infections. Reinfections of some of the groups of the surviving mice did not result in protections.

Animals↗
PubMed1996

The pheromone response factor coordinates filamentous growth and pathogenicity in Ustilago maydis.

In Ustilago maydis, the a and b mating type loci regulate cell fusion, filamentous growth and pathogenicity. The a locus encodes a pheromone-based cell recognition system, and the b locus specifies two homeodomain proteins. The expression of all genes in the a and b loci is induced by pheromone. We have identified a HMG protein (Prf1) that binds sequence specifically to pheromone response elements present in the a and b loci. prf1 mutants do not express the a and b genes and are sterile. The disruption of prf1 in pathogenic haploid strains results in a loss of pathogenicity. The constitutive expression of the b genes restores pathogenicity and induces filamentous growth in the absence of the pheromone signal. These results provide evidence that pheromone signalling, filamentous growth and pathogenic development are linked through Prf1.

Amino Acid Sequence↗
PubMed1995

[Pathogenic role of intracellular energy insufficiency (hypoenergy) in the development of circulatory collapse (hemodynamic shock)].

Hemodynamic shock syndrome represents an acute circulatory failure due to a decrease of arteriovenous pressure gradient. Three unrelated groups of processes, cardiogenic, vasohypotonic and hypovolemic mechanisms, are possible starting points of the shock syndrome pathogenesis. The basic features of those principal pathogenic steps are outlined in the paper. In addition, clinical practice very often encounters a complex forms of the syndrome, which include two or all three basic pathogenic mechanisms simultaneously. Direct consequence of arteriovenous pressure gradient loss is diminishing perfusion of tissues. Tissue hypoperfusion causes a progressive depletion of cellular energy rich compounds. Such lowering of cellular ATP concentration (cellular hypoenergosis), very often less than 0.1 mmol/L, plays an important pathogenic role in the conversion of homeostatic regulation processes from a negative into a positive feedback mode. Positive feedback regulation amplifies deterioration of arteriovenous blood pressure gradient loss, which reversely intensifies the degree of energy depletion in tissues. Individual cell death decreases a tissue adjustment capacity to hypoperfusion. The critical step leading to a decompensation (systemic failure) or progressive phase of the shock is the reversal of the homeostasis into the positive feedback mode of action. Final outcome of the syndrome reflects a degree of compensation capacity loss as well as irreversible tissue alterations. Clinical manifestations correlate with the underlying pathogenic processes. Short summary of clinical correlative relations with the pathogenic processes, at the cellular, molecular and/or energy level, is given in the paper.

Adenosine Triphosphate↗
PubMed1996

[The relationship between placental pathology and certain pathogens detected in paraffin-embedded tissues in cases of intrauterine growth retardation].

OBJECTIVE: To study the relationship between placental pathology and certain pathogens detected in paraffin-embedded placental tissues in cases of intrauterine growth retardation (IUGR). METHODS: The PCR-DNA techniques were used for determination of pathogens, including toxoplasma, cytomegalovirus and herps simplex type II in paraffin-embedded placental tissues from 53 cases of IUGR. RESULTS: Among 53 cases of IUGR, the pathogens were detected in 19 cases (35.85%). The relationships of pathogens detected to placental pathology were analyzed. Pathogens were found in 10 of 18 placentas with villitis, 7 of 11 placentas with villous maturation retarded and 2 of 3 intervillous space infections respectively. The incidence of infection in the pathological placentas was 59.38%. CONCLUSIONS: The study suggested that the haematogenous infections could play important roles in unknown causes of IUGR.

Adult↗
PubMedDate not supplied

Influence of the host system on the pathogenicity, immunogenicity, and antigenicity of infectious bursal disease virus.

The effect of the host system on the pathogenicity, immunogenicity, and antigenicity of infectious bursal disease virus (IBDV) was investigated. One classic (SAL) and one variant strain (IN) of IBDV were passaged separately six times in three host systems, namely BGM-70 continuous cell line, primary chicken embryo fibroblast (CEF) cells, or embryonating chicken eggs (embryos) or one time in the bursa of Fabricius (BF) of specific-pathogen-free (SPF) chickens. Passage in BGM-70 cells or CEF cells resulted in loss of pathogenicity, but viruses passaged in embryos or BF maintained their pathogenicity. For the immunogenicity study, the viruses described above were used to prepare live and inactivated vaccines, containing 10(3) mean embryo infectious doses (EID50s) and 10(5) EID50s respectively. These vaccines induced different levels of protection. It was concluded that the antigen titration methodology employing embryonating chicken eggs was not suitable for titration of viruses propagated in other host systems because of varying degrees of adaptation and/or pathogenicity of the viruses resulting in variability in antigen mass of the tested vaccines. To test this assumption, an antigen-capture enzyme-linked immunosorbent assay was used as a titration system to compare the antigenicity of viruses propagated in BGM-70 cells or BF. Preparations containing similar antigen masses were inactivated then inoculated into two age groups of SPF chickens and antibody titers were monitored. During the experimental period, the geometric mean virus-neutralizing (VN) antibody titers of the vaccinated groups did not differ significantly (P > 0.05).

Animals↗
PubMed1996

Wastewater treatment and elimination of pathogens: new prospects for an old problem.

Although the development of wastewater treatment technology is more than one hundred years old, most wastewater treatment plants existing today do not eliminate pathogens satisfactorily. Even in highly developed nations, receiving waters, serving in many cases as drinking water resources, are contaminated with pathogens. Surface waters also contain large concentration of phosphate due to long lasting wastewater discharges. Cyanobacteria and algal overgrowth is the consequence. Present drinking water technology only partially overcomes the pollution; it can not be ruled out that drinking water originating from polluted resources contains pathogens. This situation frequently goes on unnoticed because current indicator organisms are not representative for all pathogens. As studies have shown that small concentrations of pathogens also pose a risk for the consumer health, this state of affairs is a matter of concern. Microfiltration technology is able to significantly eliminate bacteria and protists from wastewater. Viruses, although smaller than the pore size of the filters, are reduced too because, in wastewater, they are frequently bound to larger particles. If the microfiltration of wastewater is preceded by the addition of coagulants for the precipitation of phosphate, the precipitate will be retained by the filter. The effluent obtained contains very low concentrations of phosphate. As viruses also adsorb to the precipitate, the amount of viruses eliminated increases and with increasing amounts of coagulant they become undetectable.

Communicable Disease Control↗
PubMed1977

[Comparing studies on biochemical characteristics for pathogenicity and antibiotic resistance of staphylococci (author's transl)].

735 strains of staphylococci obtained from routine material were examined for biochemical characteristics claimed by BAIRD-PARKER (Bergey's Manual of Determinative Bacteriology, 1974) to be pathogenic features); the behaviour of the strains showing these properties was then compared to that of 12 antibiotics. Thereby, 237 of the 735 strains (32.2%, tab. 2) were positive for the combination of pathogenic features as proposed by BAIRD-PARKER (aerobic and anaerobic mannitol fermentation, beta-haemolysis, and positive coagulase reactivity), with approx. 30% of the Staphylococcus strains showing white pigmentation and 70% of them showing yellow pigmentation. The number of strains showing the combination of aerobic mannitol fermentation, beta-haemolysis, and positive coagulase reactivity was significantly higher: 341 out of 735 strains (46.4%, tab. 2). A comparison of the resistance to 12 antibiotics with the combination of pathogenic features of BAIRD-PARKER (Tab. 4) showed that he white Staphylococcus strains with this combination exhibited a significantly higher resistance to 6 of the tested antibiotics than the white Staphylococcus strains not showing these characteristics. Such a correlation between biochemical characteristics and resistance behaviour could not be demonstrated in the yellow Staphylococcus strains. The value of biochemical characteristics as features of pathogenicity and the resistance behaviour of staphylococcal strains to antibiotics in vitro for their pathogenic behaviour in vivo is discussed in relation to comparable results reported by other authors.

Anti-Bacterial Agents↗
PubMed1996

[Avian Chlamydia psittaci phyla and their pathogenic significance for turkeys].

The present study demonstrates that Chlamydia psittaci is an important cause of respiratory disease in turkeys in Europe. The serotyping of isolates revealed that European turkeys frequently become infected with Chlamydia psittaci serovar D strains, but also can become infected with serovar A and B strains. In turkeys, differences in pathogenicity were observed not only between strains belonging to the serovars A (strain 84/55), serovar B (strain 89/1326) and serovar D (Texas Turkey strain and strain 92/1293), but also between two strains belonging to the same serovar D (Texas Turkey strain and strain 92/1293). In order to find an explanation for these differences in pathogenicity, the pathogenesis of the infection was studied in specific pathogen free turkeys. However, for all three serovars examined a similar pathogenetic sequence of events was deduced. In order to try and elucidate the observed differences in pathogenicity between different Chlamydia psittaci strains, the bacterium-host cell interaction was studied in BGM cell culture using transmission electron microscopy and immuno electron microscopy. Strains most pathogenic for turkeys, namely the serovar A strain and strain 92/1293 (serovar D) produced significantly larger inclusions with more numerous infectious organisms, produced the most severe degenerative changes in the host cell an also replicated freely in the cytoplasm of the host cell.

Animals↗
PubMed1997

[Pathogenic organisms in milk and milk products: the situation in France and in Europe].

Milk and dairy products harbour a natural microbial flora and/or other micro-organisms, which vary within the wide range of products available on the French market. The origin of contamination by pathogenic bacteria varies with the type of product and the mode of production and processing. Contamination of milk and dairy products by pathogenic micro-organisms can be of endogenous origin, following excretion from the udder of an infected animal. Contamination may also be of exogenous origin, through direct contact with infected herds or through the environment (e.g. water, personnel). Treatment and processing of milk can inhibit or encourage the multiplication of micro-organisms. The authors describe the relevant aspects of bacterial physiology and ecology, the occurrence of bacteria in dairy products, and the public health significance for each of the principal micro-organisms found in such products. Bacteria most frequently involved are mycobacteria, Brucella sp., Listeria monocytogenes, Staphylococcus aureus and enterobacteria (including toxigenic Escherichia coli and Salmonella). At present, systems of testing and surveillance are required for the control of pathogenic bacteria in milk and dairy products, as specified by regulations currently being developed for all countries in the European Union. Preventive measures should take into account the well-established facts concerning the potential microbiological impact of pathogenic bacteria on milk and dairy products. There should be increased recourse to risk analysis methods to assess the threat to the consumer with regard to the presence of pathogenic bacteria in food.

Animals↗
PubMed2002

Molecular diagnostic procedures for production of pathogen-free propagation material.

Production of disease-free propagation material is a major means of controlling most bacterial diseases of plants, particularly when neither resistant clones nor effective chemical treatments are available. For this purpose sensitive, specific and rapid detection methods are required. The advent of molecular biology and, in particular, the polymerase chain reaction (PCR) has opened new ways for the characterization and identification of plant pathogens and the development of disease-management strategies. PCR-based detection methods rely on the development of primers for the specific detection of the pathogen. The use of pathogenicity genes as targets for primer design is the preferred procedure for obtaining specific primers but other procedures may also be useful for this purpose. In the present review we describe four examples of procedures for detecting four important bacterial pathogens in Israel: Erwinia herbicola pv gypsophilae in gypsophila, Xanthomonas campestris pv pelargonii in geranium, Agrobacterium tumefaciens in asters and roses, and Xanthomonas campestris pv campestris in crucifers. Procedures for constructing specific PCR primers for each bacterium are illustrated and discussed as well as the combination of PCR with other methods.

Agrobacterium tumefaciens↗
PubMedDate not supplied

Clearance of blood-borne pathogens mediated through bispecific monoclonal antibodies bound to the primate erythrocyte complement receptor.

The primate erythrocyte complement receptor facilitates both the immune adherence reaction and the immune complex clearance properties of primate erythrocytes. These phenomena have been studied for more than 40 years. However, it has only recently become apparent that these characteristics of primate erythrocytes may be useful in the generation of a therapy based on bispecific monoclonal antibodies. Our approach uses bispecific monoclonal antibody constructs (heteropolymers) that promote binding of specific target pathogens to primate erythrocytes via the complement receptor. Once bound to the erythrocytes, the pathogen-heteropolymer complex should be cleared from the circulation, phagocytosed and destroyed in the liver. Results with several prototype target pathogens in monkey models indicate it may be possible to use this technology to develop a robust and general therapy for the treatment of diseases associated with blood-borne pathogens.

Animals↗
PubMed2025

Pathogenicity assessment of genetic variants identified in patients with severe hypertriglyceridemia: Novel cases of familial chylomicronemia syndrome from the Dyslipidemia Registry of the Spanish Atherosclerosis Society.

PURPOSE: Genetic testing is required to confirm a diagnosis of familial chylomicronemia syndrome (FCS). We assessed the pathogenicity of variants identified in the FCS canonical genes to diagnose FCS cases. METHODS: 245 patients with severe hypertriglyceridemia underwent next-generation sequencing. Preliminary variant pathogenicity criteria and classification, based on the American College of Medical Genetics and Genomics guidelines, were obtained online and verified. Phenotype evaluation was based on lipoprotein lipase activity deficiency, a clinical score, and/or type I hyperlipoproteinemia determined in 25 patients. RESULTS: Twenty-four biallelic variants were analyzed. Evidence-based criteria allowed the reclassification of 8 likely pathogenic (LP) variants in the LPL, APOA5, and LMF1 genes into pathogenic (P) and the change of 2 variants of uncertain significance (VUS) to LP. Conversely, 2 variations in LMF1 remained as VUS. Additionally, 1 variant in LPL and 2 in GPIHBP1 were likely benign. Twenty FCS cases had biallelic P/LP variants and 1 patient, with an FCS phenotype, harbored biallelic VUS. FCS was excluded from 4 patients with pathogenic/likely benign combinations. CONCLUSION: The analysis of the clinical and biochemical features of patients with variants in the FCS canonical genes allowed a confident variant classification that helped in the diagnosis of novel FCS cases.

Humans↗
PubMed2006

Incorporating geographic settings into a social network analysis of injection drug use and bloodborne pathogen prevalence.

Using social network analysis, we investigated how communal meeting places can link injection drug user (IDU) populations and create opportunities for the transmission of bloodborne pathogens. In our locale, specific hotels played a key role in the injection drug scene. Within this hotel network some IDU injected at only one hotel while others injected at multiple hotels; this latter group potentially acted as spatial bridges linking relatively distinct hotel networks. Pathogen prevalence showed a gradation with the highest prevalence occurring at the centre of the network. Consistent with pathogen prevalence, people most central to the network were more likely to engage in risky injection practices. Incorporating geographic place into analyses involving IDU can contribute to an understanding of pathogen transmission patterns in an area and assist public health efforts to develop targeted intervention programs.

Adult↗
PubMed2006

Mycoplasma hyorhinis in Taiwan: diagnosis and isolation of swine pneumonia pathogen.

This study attempted to determine whether one multiplex polymerase chain reaction (PCR) is an effective adjunct method for diagnosing Mycoplasma hyopneumoniae and Mycoplasma hyorhinis infection, and whether M. hyorhinis should be considered as an enzootic pneumonia or porcine respiratory disease complex pathogen in Taiwan. To our knowledge, this study is the first to isolate and identify M. hyorhinis as a porcine pathogen in Taiwan. A novel isolation method and a multiplex PCR test were applied to detect and isolate M. hyorhinis. The correlation of M. hyorhinis with swine pneumonia was also examined using a challenge test. Based on weight, 18 pigs were assigned to three groups and housed throughout the study in a specific-pathogen-free (SPF) facility and provided with aseptic feed and water. Groups 1 (n=6) and 2 (n=6) were challenged with 5mL M. hyorhinis culture via tracheal intubation on day 1. The M. hyorhinis strains ATIT-1, -3, and-7 were used to infect group 1 and the strain ATCC 27717 was used for group 2. Culture medium was replaced by phosphate-buffered saline in group 3 (n=6). All pigs were slaughtered on day 28, and their lungs were removed for examination of lesions. Of the six pigs in group 1 challenged with wild-type strains, two had typical mycoplasma pneumonia lesions. No gross lung lesions were observed in groups 2 and 3. Although further examination is necessary to confirm that wild-type strains can cause pneumonia, it appears that M. hyopneumoniae is no longer the only mycoplasma pathogen implicated in the diagnosis of swine enzootic pneumonia (SEP).

Animals↗