Comparison of the effects of UV-A radiation on Leptospira interrogan serovar Bataviae, Canicola and Pomona

Motivated by the lack of related studies and an insufficient understanding of the response of pathogenic spirochetes, including leptospira to ultraviolet-A (UV-A) (or other stresses), we comparatively studied the effects of UV-A radiation on the Leptospira interrogans serovar Bataviae,Canicola and Pomona. The main purpose of this work was to investigate the effects of UV-A irradiation—both short term (immediate) and long term (post-irradiation)—on leptospires at different UV-A dosages, controlled by the duration of exposure time. It was observed that survival fractionslinearly decrease from 100 to about 70, 60 and 50% for serovar Pomona, Bataviae and Canicola, respectively. This indicates that, for different serovars, UV-A irradiation has a quantitatively different effects on growth. Short term effects suggest that Pomona may be more resistant to UV-A than the other serovars. Long term effects show that, when compared with the control group, the treated groups of bacteria re-grow when the exposure time is equal or lesser than 6 h (~ 2 - 6), while the groupsexposed for 12 h or longer experienced little change or a slight decrease. This may indicate that UV-A radiation is able to inhibit the growth of bacteria, but does not prevent self-defense from taking place. UV-A radiation’s effect on antigenic components was also investigated. The immunoblotting method was used and the results are supported by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results. Possible explanations for these results are discussed

Effects of Static Magnetic Field on Growth of Leptospire, Leptospira interrogans serovar canicola: Immunoreactivity and Cell Division

The effects of the exposure of the bacterium, Leptospira interrogans serovar canicola to a constant magnetic field with magnetic flux density from a permanent ferrite magnet = 140 mT were studied. Changes in Leptospira cells after their exposure to the field were determined on the basis of changes in their growth behavior and agglutination immunoreactivity with a homologous antiserum using darkfield microscopy together with visual imaging. The data showed that the exposed Leptospira cells have lower densities and lower agglutination immunoreactivity than the unexposed control group. Interestingly, some of the exposed Leptospira cells showed abnormal morphologies such as large lengths. We discussed some of the possible reasons for these observations.Comment: 21 pages, 5 figures, 1 tabl

Use of immunoblotting as an alternative method for serogrouping Leptospira.

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2015-11-10T12:41:53Z No. of bitstreams: 1 Doungchawee G Use of immunoblotting as an....pdf: 155445 bytes, checksum: c9aa29f37f22843335663c13e0f3cb52 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2015-11-10T12:55:07Z (GMT) No. of bitstreams: 1 Doungchawee G Use of immunoblotting as an....pdf: 155445 bytes, checksum: c9aa29f37f22843335663c13e0f3cb52 (MD5)Made available in DSpace on 2015-11-10T12:55:07Z (GMT). No. of bitstreams: 1 Doungchawee G Use of immunoblotting as an....pdf: 155445 bytes, checksum: c9aa29f37f22843335663c13e0f3cb52 (MD5) Previous issue date: 2007Mahidol University. Faculty of Science. Department of Pathobiology. Bangkok, ThailandMahidol University. Faculty of Science. Department of Biochemistry. Bangkok, ThailandFundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Weill Medical College of Cornell University. Division of International Medicine and Infectious Disease. New York, NY, USAMahidol University. Faculty of Science. Department of Pathobiology. Bangkok, ThailandNational Institute of Health. Research Center for Leptospira Laboratory. Nonthaburi, ThailandMahidol University. Medical Molecular Biology Unit. Office for Research and Development. Department of Medicine Siriraj Hospital. Bangkok, ThailandLeptospirosis is a worldwide zoonotic disease caused by a spirochaete bacterium, Leptospira. Serological detection of this micro-organism basically relies on a conventional microscopic agglutination test (MAT), which has some limitations and disadvantages. In the present study, immunoblotting has been applied as an alternative method for differentiating serogroups and serovars of leptospires. Leptospiral whole-cell lysates from a total of 26 serovars were subjected to immunoblotting using rabbit antisera against individual serovars. The findings clearly demonstrated that the pattern of immunoreactive bands could be used to differentiate between leptospires of different serogroups, consistent with MAT results. There was a multi-band pattern that was unique for the pathogenic Leptospira antigens and was not observed in the non-pathogenic Leptospira biflexa and non-leptospiral bacteria (i.e. Escherichia coli, Burkholderia pseudomallei and Helicobacter pylori). For pathogenic Leptospira species, a prominent smear-like band at approximately 19-30 kDa was present when the antigens were probed with the homologous antisera. The molecular size of the prominent band, although it showed a cross-reaction between members within the same serogroup, differed among different serovars. The results obtained from polyclonal antibodies (antisera) were confirmed using mAb. With its simplicity and safety of experimental procedures, it is proposed that immunoblotting may potentially be useful as an alternative method for differentiating between serogroups of leptospires

Early Diagnosis of Leptospirosis by Immunoglobulin M Immunoblot Testing▿

There is an urgent need for the development of serodiagnostic approaches with improved sensitivity for patients with acute leptospirosis. Immunoblots were performed on 188 sera collected from 74 patients with laboratory-confirmed early leptospiral infection to detect immunoglobulin M (IgM) antibodies to antigens pooled from 10 leptospiral strains prevalent in Thailand. Sera from patients with other febrile diseases served as controls. IgM reactivity to seven distinct antigens, with apparent molecular masses of 14 to 18, 19 to 23, 24 to 30, 32, 35/36, 37, and 41/42 kDa, was observed. The low-molecular-mass 14- to 18-kDa band was the most frequently detected antigen, being recognized in sera from 82.4% of patients during the first 3 days after the onset of symptoms. We evaluated the accuracy of the IgM immunoblot (IgM-IB) test by using reactivity to the 14- to 18-kDa band and/or at least two bands among the 19- to 23-, 24- to 30-, 32-, 35/36-, 37-, and 41/42-kDa antigens as the diagnostic criterion. The sensitivities of the IgM-IB test and the microscopic agglutination test (MAT) were 88.2% and 2.0%, respectively, with sera from patients 1 to 3 days after the onset of symptoms. In contrast, the IgM-IB test was positive with only 2/48 (4.2%) sera from patients with other febrile illnesses. The high sensitivity and specificity of the IgM-IB test for acute leptospirosis would provide greatly improved diagnostic accuracy for identification of patients who would benefit from early antibiotic intervention. In addition, the antigens identified by the IgM-IB test may serve as components of a rapid, accurate, point-of-care diagnostic test for early leptospirosis

Environmental and Behavioral Risk Factors for Severe Leptospirosis in Thailand

A nationwide prevention and control campaign for leptospirosis in Thailand has led to a decreased incidence rate, but the mortality and case fatality rates have remained stable. Regarding the limited knowledge of risk factors, a case-control study of the association between environmental and behavioral exposure with severe leptospirosis was implemented to identify the risk factors among adults in Thailand. The study was conducted in 12 hospital-based sites. Hospitalized patients with suspected clinical symptoms of leptospirosis were tested for leptospirosis by culture, loop mediated isothermal amplification (LAMP), real-time PCR, and the microscopic agglutination test (MAT). All participants answered a standardized questionnaire about potential risk factors. Risk factors were identified by univariable and multivariable logistic regression. Of the 44 confirmed cases, 33 (75.0%) presented with severe illness, as determined by clinical criteria, and were categorized as severe cases. Non-severe cases were defined as patients with non-severe symptoms of leptospirosis. Living nearby a rubber tree plantation (adjusted OR 11.65, 95% CI 1.08–125.53) and bathing in natural bodies of water (adjusted OR 10.45, 95% CI 1.17–93.35) were both significantly associated with an increased risk of severe leptospirosis. We recommend designating rubber plantations in Thailand as high-risk zones and closely monitoring hospitalized patients in those areas