LOCALIZATION AND BACTERIOSTASIS OF VIBRIO INTRODUCED INTO THE PACIFIC WHITE SHRIMP, LITOPENAEUS VANNAMEI

Burgents, Joseph E., Louis E. Burnett, Eric V. Stabb, Karen G. Burnett

ABSTRACT
Although numerous mechanisms of immune defense have been described in crustaceans, the tissue distribution and fate of live bacteria introduced into the host remains unclear.  In the present study, Litopenaeus vannamei were injected with a sublethal dose of kanamycin-resistant Vibrio campbellii expressing green fluorescent protein.  Accumulation of intact bacteria was quantified by real-time PCR, while bacteriostasis was quantified as the percentage of intact bacteria that could not be recovered by selective plating.  Over the 240 min examined, the lymphoid organ contained the greatest number of intact V. campbellii per gram tissue as well as the lowest percentage of culturable V. campbellii compared to other tissues, including the hemolymph.  In contrast, the gills and hepatopancreas accumulated intact bacteria, but contained a significantly greater percentage of culturable bacteria than the hemolymph after 240 min.  These data suggest that the lymphoid organ plays a major role in bacterial uptake and bacteriostasis in penaeid shrimp.

Published:
Burgents, J. E., L. E. Burnett, E. V. Stabb, K. G. Burnett. 2005. Localization and bacteriostasis of Vibrio introduced into the Pacific white shrimp, Litopenaeus vannamei. Dev. Comp. Immunol. 29:681-691.

HYPOXIA AND HYPERCAPNIC HYPOXIA AFFECT THE LOCALIZATION AND BACTERIOSTASIS OF VIBRIO IN THE PACIFIC WHITE SHRIMP, LITOPENAEUS VANNAMEI

Burgents, Joseph E., Karen G. Burnett, Louis E. Burnett

ABSTRACT
Low oxygen (hypoxia) and low pH, caused by elevated CO₂ (hypercapnia), are characteristic of estuarine environments.  Although hypoxia and hypercapnic hypoxia decrease the resistance of shrimp to bacterial pathogens, the direct effects of these variables on the immune system are unknown.  Here we present evidence demonstrating in the penaeid shrimp Litopenaeus vannamei that both hypoxia and hypercapnic hypoxia affect the localization and the bacteriostasis of bacteria in various tissues.  L. vannamei were injected with a sub-lethal dose of a pathogenic strain of Vibrio campbellii expressing green fluorescent protein and resistance to kanamycin.  Real-time PCR was used to determine the number of intact V. campbellii in selected tissues; selective plating was used to quantify those bacteria that were culturable.  Under well-aerated, normoxic conditions the lymphoid organ was the main site of bacterial accumulation and killing 4 h after injection.  Exposure to hypercapnic hypoxia or hypoxia appeared to shift the overall distribution of V. campbellii from the lymphoid organ to the hepatopancreas and the gills.  Both hypercapnic hypoxia and hypoxia also increased the percentage of culturable bacteria recovered from the tissues, suggesting an overall decrease in bacteriostatic activity.

Burgents, J. E., K. G. Burnett, L. E. Burnett.  2005. Effects of hypoxia and hypercapnic hypoxia on the localization and the elimination of Vibrio campbellii in Litopenaeus vannamei, the Pacific white shrimp.  Biol. Bull. 208:159-168.