In vitro Interactions between Hemocytes of the Eastern Oyster, Crassostrea virginica Gmelin, 1791 and Cryptosporidium parvum Oocysts

Abstract

It was demonstrated by an in vitro slide phagocytosis assay that hemocytes of the Eastern oyster, Crassostrea virginica Gmelin, 1791 are capable of rapid recognition and internalization of infectious Cryptosporidium parvum (AUCP-1 strain) oocysts. The incubation of hemocyte monolayers (8.5 x 10(4) cells) that had received 6.8 x 10(5) or 3.4 x 10(5) oocysts was arrested at 5, 15, 30, 60, 90, and 120 min and the oocytes detected by acid-fast stain and immunofluorescent antibody (IFAT). An average of 20.5, 38.3, 50.2, 58.9, 69.0, and 75.0% oocysts were phagocytosed after 5, 15, 30, 60, 90, and 120 min, respectively. The intensity of fluorescence of phagocytosed oocysts significantly decreased over time (P < 0.01), and their round shape was altered. The number of cells containing oocysts and the mean number of ingested oocysts (range: 1.2-4.5 per cell) increased significantly over time (P < 0.01), whereas the numbers of nonphagocytosed oocysts that were adherent to the glass slides significantly decreased (P < 0.05). By extrapolation, the results indicate that Cr. virginica is capable of internalizing up to 6.4 x 10(6) Cryptosporidium oocysts per ml of its hemolymph.

Recovery, Bioaccumulation, and Inactivation of Human Waterborne Pathogens by the Chesapeake Bay Nonnative Oyster, Crassostrea ariakensis

“…The progressively decreasing pathogen levels in oyster tissue over time and the fact that only viable pathogens were detected indicate that nonviable cells disintegrate rapidly, most likely because they are being digested by the hemocytes (18). The best example in the present study was provided by G. lamblia cysts, which were detected no longer than 2 weeks after exposure.…”

In vitro phagocytosis of Giardia duodenalis cysts by hemocytes of the Asian freshwater clam Corbicula fluminea

“…The hemocytes of C. japonica have phagocytosed in vitro infectious Vibrio parahaemolyticus and Escherichia coli (Kumazawa and Morimoto 1992). Hemocytes of the marine shell®sh Crassostrea virginica have phagocytosed in vivo and in vitro C. parvum oocysts (Fayer et al 1997;Graczyk et al 1997b).…”

Viability and infectivity of oocysts recovered from clams, Ruditapes philippinarum , experimentally contaminated with Cryptosporidium parvum

“…oocysts from water (Fayer et al 1997;Graczyk et al 1997b;Tamburrini and Pozio 1999). Furthermore, in vitro phagocytosis of C. parvum oocysts by Eastern oyster (Crassostrea virginica) haemocytes was demonstrated after 15, 30, 60 and 120 min of incubation (Graczyk et al 1997c). Oocysts contained in Eastern oyster haemocytes were infective in mice (Fayer et al 1997.…”