Vertical and horizontal transmission of tilapia larvae encephalitis virus: the bad and the ugly.

Impairment of innate immunity in tilapia larvae after vertical and horizontal infection with the newly characterized tilapia larvae encephalitis virus (TLEV) was accessed by evaluation of cell-mediated reactive oxygen species (ROS) production in affected fish with the use of horseradish peroxidase-amplified luminol-dependent chemiluminescence assay. The priming in-vivo infection with TLEV resulted in downregulation of ROS response in both vertically- and horizontally-infected fish; this suppression was further exacerbated by specific in-vitro booster infection with the same virus. Application of Ca ionophore and phorbol myristate acetate as alternative nonspecific boosters enabled restoration of ROS release in vertically-infected but not in horizontally-infected larvae. The results indicate severe TLEV-imposed phagocyte dysfunction in affected larvae. The difference in restoration potential of ROS production after vertical and horizontal virus transmission is interpreted in the frame of principal distinctions between the two modes.

Chemiluminescent analysis of light-irradiated leukocytes as a diagnostic tool for fast identification of pathological states.

OBJECTIVE: Reactive oxygen species (ROS), mainly produced by polymorphonuclear neutrophils (PMN), are a significant part of host defense in pathologic states. We attempted to relate numbers of PMN and ROS generated within PMN to develop an alternative photochemical approach for evaluation of the potential of these cells to resist the development of inflammatory pathology. BACKGROUND DATA: Lack of sensitivity to light has been reported in healthy cells, while sensitivity to light characterizes cell pathology. METHODS: Human leukocytes from 34 donors were isolated and irradiated with a non-laser blue light (2 and 5 mW/cm(2) for 2 minutes), and a luminol-dependent chemiluminescence assay that reflects intracellular production of ROS was applied thereafter. The levels of basal chemiluminescence (BCL) were related to respective numbers of PMN. RESULTS: A light-insensitive cluster was discovered within the total sample and was considered to be a discrete nonpathological group. Following elimination of this group, the rest of the sample was divided into three well-defined light-sensitive groups, which were attributed to various pathological states, and differed in PMN numbers and BCL counts. Within these groups the two traits were interrelated, and each PMN range was associated with a respective level of intracellular ROS. CONCLUSIONS: Leukocyte responsiveness to light can be used for discrimination between pathological and nonpathological states and prognostic evaluation of pathological development. Patients exhibiting similar clinical symptoms could be divided into separate groups with potentially different outcomes. A novel definition of nonpathological states as well as the mechanism underlying the bell-shaped curve that delineates the relationship between PMN number and intracellular ROS is suggested in pathological states.

Visible light affects chemiluminescence of carp (Cyprinus carpio) blood leukocytes.

OBJECTIVE: Visible light irradiations at doses of 5 and 12 J/cm(2) were applied to carp buffy coat leukocytes. MATERIALS AND METHODS: The leukocytes response was measured by a chemiluminescence (CL) assay as basal (spontaneous) bCL and Ca ionophore-induced stimulated CL (StCL). RESULTS: The irradiation caused a significant decrease in bCL in six out of 14 fish (susceptible fish) and rendered eight out of 14 fish unsusceptible. An inhibitory effect of light intensity dependence was more pronounced at 12 J/cm(2). Furthermore, this inhibitory effect of irradiation on bCL was found in fish which displayed higher (433 +/- 90 cpm/mL) pre-irradiation bCL, compared to unsusceptible subjects (88 +/- 30 cpm/mL, p < 0.05). Similar differences in the intensity of preirradiation StCL were found between these fish groups (13,053 +/- 5086 as compared to 1077 +/- 294, p = 0.03). Moreover, the time-to-peak of StCL was significantly shorter in susceptible fish, indicating their hyper-reactivity. CONCLUSION: These data show the inhibitory effect of visible light irradiation on blood leukocyte CL response in fish. These results suggest the prevention of host hyper-response which may occur under natural conditions of fish life. An Electron Paramagnetic Resonance (EPR) study of illuminated carp blood cells reveals the formation of Ascorbate free radicals (AFR) that may explain the decrease in reactive oxygen species (ROS) concentration following irradiation.