Effect of temperature on defense parameters in Manila clam Ruditapes philippinarum challenged with Vibrio tapetis

Abstract

Brown Ring Disease (BRD), a vibriosis affecting the clam Ruditapes philippinarum, is present on the Atlantic coasts of Western Europe and is considered to be a cold water disease. The present work investigated the effect of temperature on immune response and its relationships with BRD development. Clams maintained at different temperatures (8, 14 and 21°C) were experimentally challenged with the pathogen Vibrio tapetis, the etiologic agent of BRD. Results demonstrated significant effects of temperature on disease development and on hemolymph immune parameters including total and viable hemocyte counts, lysozyme and leucine aminopeptidase activities. Thirty days after challenge, clams maintained at 21°C displayed significantly higher values for all the measured immune parameters in comparison to specimens incubated at 14°C. Improved performance of the immune system was associated with a low BRD prevalence. The recovery process, which occured mainly at 21°C, was associated with high percentages of viable hemocytes and high activities of leucine amino-peptidase and lysozyme. This laboratory study clearly demonstrates that temperature strongly affects BRD development and clam immune response during infection. Favourable immune status at higher temperature may confer upon the clam a better capacity to fight the disease agent, and therefore to recover more easily.KEY WORDS: Immunomodulation · Temperature · Hemocyte · Leucine aminopeptidase · Lysozyme · Disease · Clam · Vibrio Resale or republication not permitted without written consent of the publisherDis Aquat Org 59: [249][250][251][252][253][254][255][256][257][258][259][260][261][262] 2004 tal induction of the disease after V. tapetis challenge performed under standard conditions (14°C, 33 ‰) has shown that physiological functions such as nutrition and the immune defense system are severely affected in diseased clams , Plana 1995, Plana et al. 1996. Generally, at 14°C, the immune response in hemolymph, during the development of BRD, displays a 2-phase pattern: an early induction of cellular and humoral response in hemolymph (total hemocyte counts [THC] and enzymatic activities such as leucine aminopeptidase and lysozyme), followed by an inhibition of these defense parameters (Oubella et al. 1993, Allam et al. 2000b. In severely infected clams, a concomitant increase in THC in the extrapallial fluids is measured suggesting their mobilisation to the site of infection (Oubella et al. 1993, Allam et al. 2000a. Mass mortalities of BRD-infected clams can result from the decline of metabolic activity, sometimes associated with a septicemic invasion of V. tapetis in hemolymph and tissues (Plana et al. 1996, Allam et al. 2002.In marine invertebrates, disease prevalence is controlled by environmental factors (Harvell et al. 1999). In the case of BRD, field studies have suggested the influence of temperature on disease prevalence (Paillard et al. 1997). Along the French Atlantic coast, there is a clear boundary at the Loire river; the observed BRD prevalences...

Hemocytes of the carpet shell clam (Ruditapes decussatus) and the Manila clam (Ruditapes philippinarum): Current knowledge and future prospects

“…In laboratory experiments, temperature and salinity were shown to influence immune status of clams. In R. philippinarum, low water temperature and salinity induced a decrease in the concentration of hemocytes, lysozyme activity, and phagocytosis capacity (Reid et al, 2003;Paillard et al, 2004b). Several other laboratory experiments underscored the effects of temperature and salinity on hemocyte parameters in various bivalve species (Chu and La Peyre, 1993b;Fisher et al, 1996;Chu, 1998;Allamet al, 2002;Liu et al, 2004;Matozzo et al, 2007;Monari et al, 2007).…”

Hemolymph microbiome of Pacific oysters in response to temperature, temperature stress and infection

“…The outcome in temperate regions can be much less predictable, depending on thermal optima and ranges of hosts and pathogens (Thomas and Blanford, 2003). For example, temperatures over 20 1C are necessary for oyster summer mortalities to occur (Samain et al, 2007;Watermann et al, 2008), but it is low temperatures (o14 1C) that promote development of brown ring disease in clams (Paillard et al, 2004).…”

Impact of Brown Ring Disease on the energy budget of the Manila clam Ruditapes philippinarum

“…Disease progression is estimated by the extent of the symptomatic deposit decribed by Paillard and Maes (1994). Infected clams show depressed defence-associated activities (Allam et al, 2000;Paillard et al, 2004). The effects of BRD on Manila clams have been reviewed recently by Paillard (2004b).…”