Clearing mechanisms of Vibrio vulnificus biotype I in the black tiger shrimp Penaeus monodon

Abstract

Vibrio species' infections are a common sequelae to environmental stress or other disease processes in shrimp, but the mechanism by which the shrimp eliminate the bacteria is poorly understood. In this study, the penetration, fate and the clearing of V. vulnificus were investigated in Penaeus monodon. A bacterial disease isolate from a shrimp farm was identified as V. vulnificus biotype I. Polyclonal antiserum was raised in rabbits against the bacterium and the specificity was verified by ELISA and immunoblot against a range of Vibrio spp. and other Gram-negative bacteria. The bacteria were then administered to P. monodon juveniles by injection, immersion and oral intubation. An indirect immunoperoxidase technique was employed in a time course study to follow the bacteria and bacterial antigens in the tissue of the shrimp. Bacteria were cleared by a common route, regardless of the method of administration. Observations in immersion challenge were similar to a combination of those for oral and injection challenges. With immersion, bacteria entered the shrimp through damaged cuticle or via insertion points of cuticular setae. Shortly after entry, whole bacterial cells were observed in the haemolymph and connective tissue. They were either phagocytosed by haemocytes, or broken down outside host cells. Haemocytes containing bacterial cells or antigens (HCB) were observed in the connective tissue and haemolymph. HCB accumulated around the hepatopancreas, midgut, midgut-caecum, gills, heart and lymphoid organ. Free bacterial antigens also accumulated in the heart and lymphoid organ. Bacteria entering through the mouth by oral intubation or immersion were broken down so that only soluble or very fine particles entered the hepatopancreas. Bacterial antigens passed through the hepatopancreas into the haemolymph. Antigens were initially observed in the haemolymph sinuses and subsequently accumulated in the heart and lymphoid organ. Bacterial antigens were released from the shrimp, initially through the gills and subsequently through hepatopancreatic B-cells, branchial podocytes and sub-cuticular podocytes. KEY WORDS: Shrimp · Vibrio · Penaeus monodonResale or republication not permitted without written consent of the publisher

Time-related action of Lactobacillus plantarum in the bacterial microbiota of shrimp digestive tract and its action as immunostimulant

“…Additionally, haemocytes can aggregate into haemocytic nodules, in which cell adhesion molecules such as peroxinectin apprehend microorganisms between them (Jiravanichpaisal et al, 2006) and, then, are mechanically eliminated from the circulation through the gills (Martin et al, 2000). Haemocytes can also attach to other organs as the lymphoid organ (Braak et al, 2002) and the hepatopancreas (Alday-Sanz et al, 2002), thus, reducing the number of circulating haemocytes.…”

Vibrio parahaemolyticus and V. harveyi cause detachment of the epithelium from the midgut trunk of the penaeid shrimp Sicyonia ingentis

“…Although there have been numerous studies describing morphological changes to tissues in shrimp infected with Vibrio (Lightner & Lewis 1975, Egusa et al 1988, Aruma 1989, Chen et al 1992, de la Peña et al 1993, Jiravanichpaisal & Miyazaki 1994, Sung et al 1994, Hameed 1995, Lee et al 1996, Esteve & Herrera 2000, Alday-Sanz et al 2002, this is the first to demon-25…”

“…The hemocytes associated with the basal lamina of S. ingentis are well placed to fight pathogens passing into the body through the MGT. Longer-term studies are needed to determine if fixed hemocytes and other immune responses (Alday-Sanz et al 2002, van de Braak et al 2002 can defend the MGT until the intact epithelial layer can be restored or if death of a shrimp lacking the epithelium is inevitable. Ingested pathogens like Vibrio spp., which cause detachment of the epithelium in the MGT, can affect high mortality in S. ingentis by eliminating 2 layers that protect the shrimp from infections: the epithelium and the peritrophic membrane it secretes.…”

“…However, Vibrio spp. are among the chitinoclastic bacteria associated with shell disease (Cook & Lofton 1973) and may enter through wounds in the exoskeleton or pores (Jiravanichpaisal & Miyazaki 1994, Alday-Sanz et al 2002. The gills may appear susceptible to bacterial penetration because they are covered by a thin exoskeleton (Taylor & Taylor 1992), but their surfaces are cleaned by the setobranchs (Bauer 1998).…”

Characterization of abalone Haliotis tuberculata–Vibrio harveyi interactions in gill primary cultures

“…Although the entrance routes of V. harveyi bacteria in abalone have not yet been identified, recent studies evidenced that the gills might be directly infected by bacteria (Travers et al 2008a). In decapod crustacea, the gills have been shown as the main site of bacterial accumulation, suggesting a role of this tissue in the interactions with pathogens (Martin et al 1993;Alday-Sanz 2002;Burgents et al 2005).…”