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Updated: Aug 29, 2026
Tractable Mammalian Cell Infections with Protozoan-primed Bacteria
Published on: April 2, 2013
Supplementation of Perkinsus marinus cultures with host plasma or tissue homogenate enhances their infectivity
Christopher G Earnhart1, Mary Ann Vogelbein, Gwynne D Brown
1Department of Environmental and Aquatic Animal Health, School of Marine Science, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA.
Abstract:
The protozoan oyster parasite Perkinsus marinus can be cultured in vitro in a variety of media; however, this has been associated with a rapid attenuation of infectivity. Supplementation of defined media with products of P. marinus-susceptible (Crassostrea virginica) and -tolerant (Crassostrea gigas, Crassostrea ariakensis) oysters alters proliferation and protease expression profiles and induces differentiation into morphological forms typically seen in vivo. It was not known if attenuation could be reversed by host extract supplementation. To investigate correlations among these changes as well as their association with infectivity, the effects of medium supplementation with tissue homogenates from both susceptible and tolerant oyster species were examined. The supplements markedly altered both cell size and proliferation, regardless of species; however, upregulation of low-molecular-weight protease expression was most prominent with susceptible oysters extracts. Increased infectivity occurred with the use of oyster product-supplemented media, but it was not consistently associated with changes in cell size, cell morphology, or protease secretion and was not related to the susceptibility of the oyster species used as the supplement source.
Insights
Supplementing oyster parasite Perkinsus marinus cultures with oyster extracts improved infectivity. This enhancement occurred regardless of oyster species, suggesting a universal mechanism for reversing parasite attenuation in vitro.
Area of Science:
- Marine biology
- Parasitology
- Aquaculture
Background:
- Perkinsus marinus is a protozoan oyster parasite.
- In vitro culturing of P. marinus leads to loss of infectivity (attenuation).
- Oyster extracts can alter parasite proliferation and protease expression.
Purpose of the Study:
- To investigate if host oyster extract supplementation can reverse P. marinus attenuation.
- To examine the correlation between culture changes and infectivity.
- To determine if oyster species susceptibility influences the reversal of attenuation.
Main Methods:
- Culturing P. marinus in vitro.
- Supplementing culture media with tissue homogenates from susceptible (Crassostrea virginica) and tolerant (Crassostrea gigas, Crassostrea ariakensis) oysters.
- Analyzing changes in cell size, proliferation, protease expression, and infectivity.
Main Results:
- Supplementation altered cell size and proliferation irrespective of oyster species.
- Upregulation of low-molecular-weight proteases was more pronounced with susceptible oyster extracts.
- Increased infectivity was observed with supplemented media but not consistently linked to specific morphological or protease changes.
Conclusions:
- Oyster extract supplementation can enhance P. marinus infectivity in vitro.
- The beneficial effect on infectivity is not dependent on the susceptibility of the oyster species used for extract.
- Further research is needed to elucidate the exact mechanisms driving infectivity enhancement.
