El presente estudio tuvo como objetivo determinar la presencia de anticuerpos de cinco serovares de Leptospira spp en cuyes de crianza familiar-comercial en Cajamarca, Perú. Se colectaron muestras de ...sangre de 242 cuyes, aparentemente sanos y destinados a consumo de cinco granjas. Los sueros fueron procesados mediante la prueba de microaglutinación (MAT), considerando títulos >1/100 de serorreactividad como seropositivos. Se utilizaron cepas de referencia de los serovares Bratislava, Canicola, Hardjo, Icterohaemorrhagiae y Pomona. Se encontraron seroprevalencias de 40.50% (98/242) (IC95%: 34.3-46.7%) de anticuerpos contra Leptospira spp. Los serovares reactivos fueron Icterohaemorrhagiae (19.01%, 46/242), Canicola (16.53%, 40/242) y Pomona (8.68%, 21/144). No hubo serorreactividad para los serovares Bratislava y Hardjo. No hubo asociación estadística con las variables sexo o granja. La seropositividad indica exposición y circulación de Leptospira spp, lo cual representa un riesgo de salud pública y salud animal.
The mechanisms of disease pathogenesis in leptospirosis are poorly defined. Recent developments in the application of genetic tools in the study of Leptospira have advanced our understanding by ...allowing the assessment of mutants in animal models. As a result, a small number of essential virulence factors have been identified, though most do not have a clearly defined function. Significant advances have also been made in the in vitro characterization of leptospiral interaction with host structures, including extracellular matrix proteins (such as laminin, elastin, fibronectin, collagens), proteins related to hemostasis (fibrinogen, plasmin), and soluble mediators of complement resistance (factor H, C4b-binding protein), although none of these in vitro findings has been translated to the host animal. Binding to host structures may permit colonization of the host, prevention of blood clotting may contribute to hemorrhage, while interaction with complement resistance mediators may contribute to survival in serum. While not a classical intracellular pathogen, the interaction of leptospires and phagocytic cells appears complex, with bacteria surviving uptake and promoting apoptosis; mutants relating to these processes (such as cell invasion and oxidative stress resistance) are attenuated in vivo. Another feature of leptospiral biology is the high degree of functional redundancy and the surprising lack of attenuation of mutants in what appear to be certain virulence factors, such as LipL32 and LigB. While many advances have been made, there remains a lack of understanding of how Leptospira causes tissue pathology. It is likely that leptospires have many novel pathogenesis mechanisms that are yet to be identified.
Leptospirosis is a disease caused by pathogenic spirochetes of the genus Leptospira, transmitted by wild and domestic animals. Rodents play a fundamental role in the transmission cycle of this ...zoonosis but the function of reptiles is unknown. For example, crocodilians could play an important role in the transmission of this disease by living in ideal environments (bodies of shallow water and high temperatures) for the colonization of this bacterium. However, few studies have documented the presence of zoonotic diseases in caiman populations. Our objective was to assess the prevalence of antibodies to leptospira and the presence of Leptospira spp. in wild and captive Caiman latirostris. Blood samples were taken from 45 individuals (20 wild and 25 captive). Before extraction, we cleaned each caiman's neck in order to prevent contamination of samples. We determined the presence of antibodies in serum by microscopic agglutination test (MAT) and polymerase chain reaction (PCR) to detect DNA of the bacteria. We excluded 9 of the 45 samples analyzed by MAT because 5 had lipemic serum and 4 were contaminated (colonized by other organisms). Of the 36 caimans studied by microscopic agglutination test (MAT), 56% (20/36) were considered reactive (titers ≥50). In 74% (14/19) of captive samples and 35% (6/17) of wild samples, antibodies to leptospira were detected by MAT. The serogroup with highest occurrence was Pyrogenes (85%, n = 17/20), presenting coagglutinations with Icterohaemorrhagiae (25%, n = 5/20). One sample from a captive animal was positive for PCR, and we could not isolate leptospires because of agar contamination. Of the 45 blood agar media, 17.8% were contaminated and the rest were negative. This work determined the presence of Leptospira spp. in one caiman and a high prevalence of antibodies in captive caiman relative to wild individuals.
Microbiology; Immunology; Bacteria; Broad-snouted caiman; Leptospire; Reptiles; Zoonosis
The leptospiral outer membrane Haake, David A; Zückert, Wolfram R
Current Topics in Microbiology and Immunology,
01/2015, Letnik:
387
Journal Article, Book Chapter
Recenzirano
Odprti dostop
The outer membrane (OM) is the front line of leptospiral interactions with their environment and the mammalian host. Unlike most invasive spirochetes, pathogenic leptospires must be able to survive ...in both free-living and host-adapted states. As organisms move from one set of environmental conditions to another, the OM must cope with a series of conflicting challenges. For example, the OM must be porous enough to allow nutrient uptake, yet robust enough to defend the cell against noxious substances. In the host, the OM presents a surface decorated with adhesins and receptors for attaching to, and acquiring, desirable host molecules such as the complement regulator, Factor H.Factor H. On the other hand, the OM must enable leptospires to evade detection by the host's immune system on their way from sites of invasion through the bloodstream to the protected niche of the proximal tubule. The picture that is emerging of the leptospiral OM is that, while it shares many of the characteristics of the OMs of spirochetes and Gram-negative bacteria, it is also unique and different in ways that make it of general interest to microbiologists. For example, unlike most other pathogenic spirochetes, the leptospiral OM is rich in lipopolysaccharide (LPS). Leptospiral LPS is similar to that of Gram-negative bacteria but has a number of unique structural features that may explain why it is not recognized by the LPS-specific Toll-like receptor 4 of humans. As in other spirochetes, lipoproteins are major components of the leptospiral OM, though their roles are poorly understood. The functions of transmembrane outer membrane proteins (OMPs) in many cases are better understood, thanks to homologies with their Gram-negative counterparts and the emergence of improved genetic techniques. This chapter will review recent discoveries involving the leptospiral OM and its role in leptospiral physiology and pathogenesis.
Sentinel species such as crocodilians are used to monitor the health of ecosystems. However, few studies have documented the presence of zoonotic diseases in wild populations of these reptiles. ...Herein we analyzed 48 serum samples from
Crocodylus acutus
(
n
= 34) and
C. moreletii
(
n
= 14) from different sites in the state of Quintana Roo (Mexico) to detect antibodies to
Leptospira interrogans
by means of a microscopic agglutination test (MAT).
Crocodylus acutus
and
C. moreletii
tested positive to 11 and 9 serovars, respectively, with Grippotyphosa being the serovar with the highest prevalence in Cozumel island (100%), Banco Chinchorro Biosphere Reserve (70.6%), and Río Hondo (100%), while in Chichankanab Lake, it was Bratislava (75%). Titers ranged from 1:50 to 1:3200, and the most frequent was 1:50 in all study sites.
Leptospira
is present in fresh and saltwater individuals due to the resistance of the bacterium in both environments. Cases of infected people involved with crocodile handling and egg collection suggest that these reptiles could play an important role in the transmission of leptospirosis. Preventive medicine programs should consider the monitoring of reptiles, and testing the soil and water, to prevent outbreaks of leptospirosis in facilities containing crocodiles.
Modern swine production employs a high degree of technology and is organized in various production stages, in which reproduction is one of the most significant. However, reproductive losses ...associated to fetal death are still high. Fetal losses, including fetal mummification, may occur at a rate below 1.5% in a sound herd. The causes of fetal death can be very diverse, and include various infectious agents. Therefore, investigating the causes of fetal losses is important in the decision-making process related to the control and prophylaxis of the herd. The goal of this study was to carry out a molecular survey, analyzing porcine circovirus 2 (PCV2), porcine parvovirus (PPV), and pathogenic Leptospira as potential agents related to fetal death in swine farms in Southern Brazil. We collected samples from three farms with a mummified index ≥ 2.5%. Fragments of brain, lung, kidney, liver, and heart were sampled for PCR analysis. Out of 100 samples examined, 87, 68, and 22 were positive for PCV2, PPV, and Leptospira spp., respectively. Moreover, we also identified coinfections with two and three pathogens in the same sample. Our findings contribute to the spreading of scientific knowledge related to infectious causes (PPV, PCV2, and pathogenic leptospires) of fetal losses in swine, as evidenced by the high frequencies of the investigated agents.
RESUMO: A produção moderna de suínos emprega um alto grau de tecnologia e é organizada em várias etapas de produção, nas quais a reprodução é uma das mais importantes. No entanto, as perdas reprodutivas associadas à morte fetal ainda são altas. Perdas fetais, incluindo mumificação, podem ocorrer em taxa abaixo de 1,5% em rebanhos sadios. As causas da morte fetal podem ser diversas, incluindo causas infecciosas. Portanto, a investigação de causas relacionadas à ocorrência de perdas fetais é importante no processo relacionado ao controle e profilaxia do rebanho. O objetivo deste estudo foi realizar um levantamento molecular, incluindo circovírus suíno 2 (PCV2), parvovírus suíno (PPV), e leptospiras patogênicas como potenciais agentes relacionados à morte fetal em suínos no sul do Brasil. Foram coletadas amostras de três granjas com índice de fetos mumificados ≥ 2,5%. Fragmentos de cérebro, pulmão, rim, fígado e coração foram amostrados para análise por PCR. Das 100 amostras examinadas, 87 foram positivas para PCV2, 68 foram positivas para PPV e 22 foram positivas para Leptospira spp. Além disso, também identificamos co-infecções com dois e três patógenos em uma mesma amostra. Os resultados encontrados contribuem para a disseminação do conhecimento científico relacionado às causas infecciosas (PCV2, PPV e Leptospiras patogênicas) relacionadas às perdas fetais em suínos, assim como evidenciam a alta frequência dos agentes pesquisados.
We examined 33 rodents captured in an urban area of Osaka City, Japan for IgG antibodies against Seoul virus, severe fever with thrombocytopenia syndrome virus, hepatitis E virus, Leptospira ...interrogans, Yersinia pestis, spotted fever, typhus and scrub typhus group rickettsiae. We found that 3 (9.1%) and 1 (3.0%) of the 33 rodents had antibodies against L. interrogans and spotted fever group rickettsiae, respectively. DNAs of leptospires were detected from 2 of the 3 seropositive rodents, but DNA of rickettsia was not detected. Phylogenetic analysis and multiple locus sequence typing revealed that the 2 leptospires were L. interrogans belonging to a novel sequence type. There is a potential risk for acquiring rodent-borne zoonotic pathogens even in cities in developed countries.
Leptospirosis caused by pathogenic species of the genus Leptospira is a re-emerging zoonotic disease, which affects a wide variety of host species and is transmitted by contaminated water. The ...genomes of several pathogenic Leptospira species contain a gene named invA, which contains a Nudix domain. However, the function of this gene has never been characterized. Here, we demonstrated that the invA gene was highly conserved in protein sequence and present in all tested pathogenic Leptospira species. The recombinant InvA protein of pathogenic L. interrogans strain Lai hydrolyzed several specific dinucleoside oligophosphate substrates, reflecting the enzymatic activity of Nudix in Leptospira species. Pathogenic leptospires did not express this protein in media but temporarily expressed it at early stages (within 60 min) of infection of macrophages and nephric epithelial cells. Comparing with the wild type, the invA-deficient mutant displayed much lower infectivity and a significantly reduced survival rate in macrophages and nephric epithelial cells. Moreover, the invA-deficient leptospires presented an attenuated virulence in hamsters, caused mild histopathological damage, and were transmitted in lower numbers in the urine, compared with the wild-type strain. The invA revertant, made by complementing the invA-deficient mutant with the invA gene, reacquired virulence similar to the wild type in vitro and in vivo. The LD50 in hamsters was 1000-fold higher for the invA-deficient mutant than for the invA revertant and wild type. These results demonstrate that the InvA protein is a Nudix hydrolase, and the invA gene is essential for virulence in pathogenic Leptospira species.
La leptospirose est une zoonose de distribution mondiale provoquant plus d'un million de cas sévères chez l'Homme et causant des infections chez les animaux. Les agents responsables de cette maladie ...sont les espèces pathogènes du genre Leptospira, bactéries atypiques dont les mécanismes de virulence sont largement méconnus. Des vaccins humains et vétérinaires existent mais leur action est restreinte à certains sérovars qui ne reflètent que partiellement l'épidémiologie actuelle, complexe et fluctuante dans l'espace et le temps. Les objectifs de la thèse présentée dans ce manuscrit ont été d'une part de caractériser de nouveaux facteurs de virulence de Leptospira et d'autre part d'identifier des candidats vaccins capables d'induire une protection croisée dans le cadre du projet collaboratif COVALEPT mené par Merial, regroupant des partenaires académiques et industriels. Dans un premier temps, un outil de numération par cytométrie en flux, plus rapide et performant que la méthode standard, a été développé. Par la suite, l'étude de mutants générés par transposition aléatoire ou spontanés a permis d'identifier trois facteurs de virulence : LIC12144, requis pour la synthèse des lipopolysaccharides, FliM, essentiel à la motilité, et LIC11221, potentiellement impliqué dans le chimiotactisme. De plus, deux candidats vaccins, une protéine recombinante et une souche vivante atténuée, ont été conçus et ont démontré une efficacité partielle contre la maladie en modèle rongeur. En conclusion, ce travail apporte des connaissances inédites sur les facteurs de virulence de Leptospira et permet d'envisager le développement de vaccins à large spectre de protection contre la leptospirose
Leptospirosis is a worldwide zoonosis responsible for more than 1 million human cases and severe infections in animals. The causative agents are pathogenic species of Leptospira. The virulence mechanisms of these atypical bacteria remain largely unknown. Human and animal vaccines exist but the protection is restricted to a few serovars, representing only partially the complex and fluctuating epidemiology of the disease. The aims of the thesis presented in this manuscript were to characterize new virulence factors on Leptospira on the one hand and to identify new cross-protective vaccine candidates on the other hand, in the context of the COVALEPT collaborative project led by Merial, gathering industrial and academic partners. First, a flow cytometry based enumeration method for leptospires was developed, more rapid and efficient than the current standard technique. Then, the study of mutants generated by random transposition and spontaneously avirulent strains led to the identification of three virulence factors: LIC12144, required for lipopolysaccharides biosynthesis, FliM, essential for motility, and LIC11221 which may be involved in chemotaxis. Finally, two vaccine candidates conferring partial protection against the disease in a rodent model were conceived, a recombinant protein and a live attenuated strain. Altogether, this work brings new knowledge on Leptospira virulence and supports the development of broad spectrum vaccines against leptospirosis
Le réseau d’épidémiosurveillance en pathologie équine (RESPE) a mis en place, à la fin de 2008, un sous-réseau consacré à la surveillance des causes d’avortement et de perte néonatale ayant une ...importance sanitaire, économique et/ ou zoonosique. C’est à dire les herpès viroses HVE1, HVE4, l’artérite virale VAE et la leptospirose, zoonose considérée comme maladie émergente chez le Cheval. Durant ces deux premières années, les objectifs ont été globalement atteints. La surveillance des trois catégories étiologiques d’avortement a permis la diffusion d’alertes lors de cas positifs. L’avortement herpétique (HVE1) reste la première cause virale d’avortement infectieux de la Jument (5% de l’ensemble des avortements). Ces cas d’avortements herpétiques sont restés sporadiques ; bien qu’étant observés dans des effectifs parfois importants, la vaccination limite la diffusion de l’infection. Le virus HVE 4 est abortif, mais l’avortement dû à celui-ci est rare. Les leptospires sont suspectés dans 7 % et probablement impliqués dans 2% des cas. Aucun avortement dû au virus de l’artérite n’a été constaté au cours de ces deux années. Cependant, afin de mieux répondre aux objectifs fixés, il est nécessaire d’augmenter le nombre de déclarations. Il est indispensable de mettre en place un suivi systématique des foyers positifs et/ ou suspects afin d’augmenter les informations épidémiologiques. Seule l’accumulation de ces données permettra de comprendre la circulation des agents pathogènes dans les élevages et autorisera la mise en place de mesures préventives, ainsi que l’évaluation de la vaccination.
Towards the end of 2008, the RESPE epidemiological surveillance network created a sub-network to monitor equine infectious diseases responsible for abortions and neonatal losses in France, with medical, economic and/or zoonotic relevance. These diseases include herpes viral diseases EHV1, EHV4, equine viral arteritis (EVA) and leptospirosis, a zoonosis considered as an emerging disease in horses. The herpes virus EHV-1 remains a major cause of infectious abortion in mares (5% of all abortions). Cases remain sporadic, and although they occur in groups which can be quite large, vaccination may help limit the spread of infection. On the other hand, abortions due to HVE-4 are rare. Leptospira are suspected in 7% and probably involved in 2% of cases. No abortion due to equine viral arteritis has been reported over the past two years. To meet the set objectives with greater efficiency, the number of case reports must be increased by broadening the geographical and zootechnical limits, and by monitoring systematically all positive and/ or suspected foci through contact with the person reporting the cases and/ or the breeder. The accumulation of such data is the only way we will improve our understanding of the circulation of pathogens in farms, and thus be able to implement precautionary measures and evaluate the impact of vaccination.
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