RESUMEN
Mycoplasma hyopneumoniae is an economically significant swine pathogen that causes porcine enzootic pneumonia (PEP). Important processes for swine infection by M. hyopneumoniae depend on cell surface proteins, many of which are secreted by secretion pathways not completely elucidated so far. A putative type I signal peptidase (SPase I), a possible component of a putative Sec-dependent pathway, was annotated as a product of the sipS gene in the pathogenic M. hyopneumoniae 7448 genome. This M. hyopneumoniae putative SPase I (MhSPase I) displays only 14% and 23% of sequence identity/similarity to Escherichia coli bona fide SPase I, and, in complementation assays performed with a conditional E. coli SPase I mutant, only a partial restoration of growth was achieved with the heterologous expression of a recombinant MhSPase I (rMhSPase I). Considering the putative surface location of MhSPase I and its previously demonstrated capacity to induce a strong humoral response, we then assessed its potential to elicit a cellular and possible immunomodulatory response. In assays for immunogenicity assessment, rMhSPase I unexpectedly showed a cytotoxic effect on murine splenocytes. This cytotoxic effect was further confirmed using the swine epithelial PK(15) cell line in MTT and annexin V-flow cytometry assays, which showed that rMhSPase I induces apoptosis in a dose dependent-way. It was also demonstrated that this pro-apoptotic effect of rMhSPase I involves activation of a caspase-3 cascade. The potential relevance of the rMhSPase I pro-apoptotic effect for M. hyopneumoniae-host interactions in the context of PEP is discussed.
Asunto(s)
Apoptosis , Proteínas de la Membrana/metabolismo , Mycoplasma hyopneumoniae/enzimología , Neumonía Porcina por Mycoplasma/microbiología , Serina Endopeptidasas/metabolismo , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Caspasa 3/genética , Caspasa 3/metabolismo , Línea Celular , Proteínas de la Membrana/genética , Mycoplasma hyopneumoniae/genética , Serina Endopeptidasas/genética , Porcinos , Factores de VirulenciaRESUMEN
Leptospirosis is a worldwide zoonotic infection caused by pathogenic Leptospira. Synanthropic rodents are recognized carriers of leptospires; however, the role of wild rodents in the epidemiology of the disease is still incipient. In this work, we describe Leptospira strain isolated from Cavia aperea (Brazilian guinea pig). The isolated strain was characterized by partial rpoB gene sequencing, variable-number tandem-repeats and histopathological analysis. The strain was identified as Leptospira interrogans, serogroup Icterohaemorrhagiae and caused clinical signs of leptospirosis in the hamster model, attesting to its virulence. In conclusion, these findings could be useful for elucidating the epidemiological role of C. aperea in leptospirosis.
Asunto(s)
Cobayas/microbiología , Leptospira interrogans serovar icterohaemorrhagiae/aislamiento & purificación , Leptospirosis/veterinaria , Enfermedades de los Roedores/microbiología , Animales , Proteínas Bacterianas/genética , Brasil/epidemiología , Cricetinae , ADN Bacteriano/química , ADN Bacteriano/genética , Marcadores Genéticos , Riñón/microbiología , Riñón/patología , Leptospira interrogans serovar icterohaemorrhagiae/clasificación , Leptospira interrogans serovar icterohaemorrhagiae/genética , Leptospira interrogans serovar icterohaemorrhagiae/patogenicidad , Leptospirosis/epidemiología , Leptospirosis/microbiología , Mesocricetus , Repeticiones de Minisatélite/genética , Enfermedades de los Roedores/epidemiología , Análisis de Secuencia de ADN , Virulencia , ZoonosisRESUMEN
Leptospirosis is an important global zoonotic disease caused by pathogenic Leptospira spp. species. Swine leptospirosis has a major economic impact because pigs are sources of animal protein and by-products. The signs of swine leptospirosis are abortion, stillbirth, birth of weak or ill piglets, appearing 14-60 days after infection. The reference method for diagnosis of leptospirosis is the microscopic agglutination test (MAT), in which serum samples are reacted with live antigen suspensions of leptospiral serovars. However, MAT is laborious and time consuming as a diagnostic procedure when dealing with a large number of samples; therefore, efforts are being made to develop novel, sensitive, and specific diagnostic tests for leptospirosis. In this study, a recombinant LipL32 based on enzyme-linked immunosorbent assay (rLipL32/ELISA) was evaluated as a screening test for the detection of pathogenic leptospiral-specific antibodies. A total of 86 swine serum samples tested by MAT were used to develop rLipL32/ELISA. Compared to positive and negative sera tested by MAT, rLipL32/ELISA showed 100 % sensitivity, 85.1 % specificity, and 91.86 % accuracy. No positive reaction for other bacterial diseases (enzootic pneumonia and brucellosis) was observed. The rLipL32/ELISA reported in this study is a specific, sensitive, and convenient test for the detection of antibodies against swine leptospiral infection and can be used as a rapid screening test in epidemiological surveys.