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Infectious Form (infectious + form)
Selected AbstractsProductive Chlamydia trachomatis lymphogranuloma venereum 434 infection in cells with augmented or inactivated autophagic activitiesFEMS MICROBIOLOGY LETTERS, Issue 2 2009Niseema Pachikara Abstract Autophagy, a eukaryotic cellular activity leading to the degradation of cellular components, serves as a defense mechanism against facultative intracellular bacteria as well as a growth niche for the obligate intracellular bacterium Coxiella burnetii. We here demonstrate that the obligate intracellular bacterial pathogen Chlamydia trachomatis lymphogranuloma venereum strongly induced autophagy in the middle of the chlamydial developmental cycle (24 h after infection), a time point with maximal level of chlamydial replication, but not during the early stages with low overall chlamydial metabolism (before 8 h). No autophagy induction was evident in cells exposed to heat- and UV-inactivated elementary bodies (EBs, the infectious form of Chlamydia) or to inocula from which EBs had been removed before inoculation. Blocking chlamydial development with chloramphenicol also prevented autophagy induction in cells infected with infectious EBs. It appears that autophagy is activated primarily in response to the metabolic stress consequent to chlamydial replication. However, autophagy-defective ATG5,/, cells supported chlamydial development as efficiently as autophagy-proficient ATG5+/+ cells. [source] Infectious haemolytic anaemia causes jaundice outbreaks in seawater-cultured coho salmon, Oncorhynchus kisutch (Walbaum), in ChileJOURNAL OF FISH DISEASES, Issue 12 2006P A Smith Abstract In the last 9 years, epizootics of an icterus condition has affected coho salmon, Oncorhynchus kisutch (Walbaum), reared in seawater cages in southern regions of Chile. At necropsy, fish from field cases exhibited signs of jaundice accompanied by pale light-brown livers and dark spleens. Histopathological and haematological results indicated that these fish presented haemolytic anaemia. After microbiological examination no bacterial or viral agents could be identified as aetiological agents of this disease. In an infectivity trial, coho salmon, Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), were inoculated intraperitoneally with a filtrate of an organ homogenate (0.45 ,m) from a diseased coho salmon and held for 60 days in tanks supplied with fresh water. The disease was only reproduced in coho salmon in which mortalities, beginning at day 23 post-inoculation (p.i.), reached a cumulative value of 24% at day 27 p.i. This condition was transmitted to non-inoculated cohabiting coho salmon suggesting that it is a waterborne disease. Thus, this icteric condition is caused by an infectious form of haemolytic anaemia, probably of viral aetiology, and coho salmon are more susceptible than either Atlantic salmon or rainbow trout. [source] Performance of recombinant ESAT-6 antigen (ML0049) for detection of leprosy patientsLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2007O. Parkash Abstract Aims:, The study was aimed to evaluate the Mycobacterium leprae recombinant early secreted antigenic target-6 (rESAT-6) for its serological performance in leprosy patients. Methods and Results:, Employing enzyme-linked immunosorbent assay (ELISA), serum samples were tested for prevalence of immunoglobulin G antibodies against M. leprae rESAT-6. The results revealed that the sensitivity of the assay for smear-positive leprosy patients was 82·4% (14 of 17) while for smear-negative patients it was 19·4% (six of 31). Interestingly, the performance of ESAT-6-based assay was statistically comparable with anti-phenolic glycolipid-I antibody-detecting ELISA, a most widely studied serological assay in leprosy. Regarding specificity, none of the 48 controls was positive indicating that antibody response to ESAT-6 was highly specific. Moreover, a high concordance between bacterial index and anti-ESAT-6 antibody-detecting assay was noted. Conclusions:, Recombinant ESAT-6 seems to be a potential serological reagent for detection of M. leprae infection. Significance and Impact of the Study:, ESAT-6 serology may have utility for (i) early diagnosis, particularly, of highly infectious form (multibacillary, MB) of leprosy, (ii) monitoring the response in smear-positive leprosy patients during the course of the chemotherapy, (iii) classification of leprosy patients into MB and paucibacillary groups for treatment purpose. Hence, further research on these lines is warranted. [source] Legionella pneumophila couples fatty acid flux to microbial differentiation and virulenceMOLECULAR MICROBIOLOGY, Issue 5 2009Rachel L. Edwards Summary During its life cycle, Legionella pneumophila alternates between at least two phenotypes: a resilient, infectious form equipped for transmission and a replicative cell type that grows in amoebae and macrophages. Considering its versatility, we postulated that multiple cues regulate L. pneumophila differentiation. Beginning with a Biolog Phenotype MicroArray screen, we demonstrate that excess short-chain fatty acids (SCFAs) trigger replicative cells to cease growth and activate their panel of transmissive traits. To co-ordinate their response to SCFAs, L. pneumophila utilizes the LetA/LetS two-component system, but not phosphotransacetylase or acetyl kinase, two enzymes that generate high-energy phosphate intermediates. Instead, the stringent response enzyme SpoT appears to monitor fatty acid biosynthesis to govern transmission trait expression, as an altered distribution of acylated acyl carrier proteins correlated with the SpoT-dependent differentiation of cells treated with either excess SCFAs or the fatty acid biosynthesis inhibitors cerulenin and 5-(tetradecyloxy)-2-furoic acid. We postulate that, by exploiting the stringent response pathway to couple cellular differentiation to its metabolic state, L. pneumophila swiftly acclimates to stresses encountered in its host or the environment, thereby enhancing its overall fitness. [source] Murine splenocytes produce inflammatory cytokines in a MyD88-dependent response to Bacillus anthracis sporesCELLULAR MICROBIOLOGY, Issue 2 2007Ian J. Glomski Summary Bacillus anthracis is a sporulating Gram-positive bacterium that causes the disease anthrax. The highly stable spore is the infectious form of the bacterium that first interacts with the prospective host, and thus the interaction between the host and spore is vital to the development of disease. We focused our study on the response of murine splenocytes to the B. anthracis spore by using paraformaldehyde-inactivated spores (FIS), a treatment that prevents germination and production of products associated with vegetative bacilli. We found that murine splenocytes produce IL-12 and IFN-, in response to FIS. The IL-12 was secreted by CD11b cells, which functioned to induce the production of IFN-, by CD49b (DX5) NK cells. The production of these cytokines by splenocytes was not dependent on TLR2, TLR4, TLR9, Nod1, or Nod2; however, it was dependent on the signalling adapter protein MyD88. Unlike splenocytes, Nod1- and Nod2-transfected HEK cells were activated by FIS. Both IL-12 and IFN-, secretion were inhibited by treatment with B. anthracis lethal toxin. These observations suggest that the innate immune system recognizes spores with a MyD88-dependent receptor (or receptors) and responds by secreting inflammatory cytokines, which may ultimately aid in resisting infection. [source] A new technique of anterior TAP enhances the positivity of CMV by PCR in hypertensives anterior uveitisACTA OPHTHALMOLOGICA, Issue 2009P KOCH Purpose Anterior uveitis can be severely disabling. Especially, hypertensives anterior uveitis can lead to a decrease in visual acuity, posterior synechiaes, cataract, glaucoma, etc. Diagnosis is frequently complex. Two main aetiologies are retained: non infectious (auto-immunes) and infectious forms. Amongst the lasts, various aetiologies are possible. Viral anterior uveitis remained difficult to diagnose for a long time. However, since the emergence of the polymerase chain reaction (PCR), the diagnosis is definitely easier. Nevertheless, anterior TAP result is determined by different limitations including the puncture technique, the PCR primers used, and of course the investigated virus. Methods We hereby propose a new technique of anterior TAP that allowed us to increase our PCR results in CMV anterior uveitis. Two samples were obtained: firstly, a conventional anterior TAP was realised; followed by a rinsing of the anterior chamber with saline solution. A Goldman-Witmer index for rubeola was performed in the first sample. Both samples were examined for viral PCR (HSV1, 2, VZV, CMV, EBV, Rubeola) Results We did not found any side effect of the technique used by comparison with normal anterior TAP. Diagnosis was obtained in 20 of the 35 eyes tested. Rubeola diagnosis was obtained in 11/20 eyes, VZV in 1/20, HSV1 in 4/20, and CMV in 4/20. Intriguingly, CMV diagnosis was obtained in three cases only in the second syringe and not in the first Conclusion We have, to date, detected 4 cases of CMV anterior uveitis in a cohort of 35 patients with anterior uveitis. We did not meet any complication but obtained interesting results concerning CMV diagnosis, using a rinsing of the anterior chamber (second syringe). [source] | ||||||||||