Immune responses of phenoloxidase and superoxide dismutase in the manila clam Venerupis philippinarum challenged with Vibrio tapetis – Part I: Spatio-temporal evolution of enzymes' activities post-infection

Abstract

Manila clams, Venerupis philippinarum (Adams and Reeve, 1850), were experimentally challenged with two Vibrio tapetis strains: CECT4600T, the causative agent of Brown Ring Disease (BRD); and LP2 supposedly non-pathogenic in V. philippinarum. Changes in phenoloxidase (PO) and superoxide dismutase (SOD), two major enzymes involved in immunity, were studied in two tissues, the mantle and hemolymph for 30 days after infection in the extrapallial cavity. Bacterial infection in V. philippinarum resulted in modulation of PO and SOD activities that was both tissue- and time-dependent. A response at early times was detected in the mantle and was associated with significant increases in PO and SOD activities in LP2- and CECT4600T-challenged clams 36 h post injection. This first response in the mantle could be explained by the proximity to the injection region (extrapallial cavity). In the hemolymph the response occurred at later times and was associated with an increase in PO activity and a decrease in SOD activity. As hemolymph is a circulating fluid, this response delay could be due to an "integration time" needed by the organism to counteract the infection. Injections also impacted PO and SOD activities in both tissues and confirmed a difference in pathogenicity between the two V. tapetis strains.

Development of a Taqman real-time PCR assay for rapid detection and quantification ofVibrio tapetisin extrapallial fluids of clams

“…These results imply an effect of injection on animals which were supposedly infected by V. tapetis , present in their environment before sampling, despite the quarantine stage. It has already been shown that injection or handling could stimulate bacterial proliferation ( Le Bris et al, 2015 ; Jean et al, in press ). Focusing on non-injected clams, i.e., at 0d for V. tapetis - and FSW-injected clams and all the sampling times for non-injected clams, the interpretation that V. tapetis was present in individuals before sampling is corroborated: 3 individuals among 36 were already carrying bacteria on the day of injection.…”

“…In order to accurately inoculate CECT4600 T at the target dilution of 10 7 cells/mL during the experiment, enumeration of bacteria was performed to measure the absorbance at 492 nm on a Multiskan spectrophotometer (Fisher Scientific, Hampton, NH, USA). Vibrio tapetis culture density was calculated according to the formula 1.3 10 9 × DO − 3.6 10 7 CFU/mL ( Choquet, 2004 ; Le Bris et al, 2015 ).…”

Effect of nutritive status on Mytilus galloprovincialis pollution biomarkers: Implications for large-scale monitoring programs

“…Finally, LPO is indicative of the damage caused by reactive oxygen species (ROS) to cell membrane lipids, and it is useful for assessing exposure to, and the effects of pollutants in mussels (Campillo et al, 2013;Cheung et al, 2001;ICES, 2013;Regoli and Principato, 1995;Regoli, 1998). POs are enzymes involved in humoral immune defenses and are key enzymes of melanization (Luna-Acosta et al, 2011;Le Bris et al, 2014) which is the major innate defense system in invertebrates, during which highly reactive and toxic quinine intermediates are produced to form melanin by polymerization (Cerenius and Soderhall, 2004). Regarding physiological biomarkers, the measurement of the scope for growth (SFG) has also been used as a measure of stress effects caused by pollutants in marine organisms (Albentosa et al, 2012a;Bellas et al, 2014;Halldörson et al, 2005;Widdows et al, 2002Widdows et al, 2002.…”

DNA methylation is associated with expression level changes of galectin gene in mantle wound healing process of pearl oyster, Pinctada fucata

“…The molluscs performed humoral and cellular immune reactions in dealing with pathogens and stress responses [1,2]. In immune reactions, pattern recognition proteins such as the galectins are involved in the recognition of pathogen-associated molecular patterns of microorganisms [3].…”