title: Viral gametocytic hypertrophy of Crassostrea gigas in France: from occasional records to disease emergence?
abstract: Viral gametocytic hypertrophy was reported for the first time in 2001 in Pacific oyster Crassostrea gigas in France. Since this date, the number of reported cases and the distribution area have increased every year; however, the cases are not associated with macroscopic signs or increased mortality rates. Both male and female gametes were hypertrophied and basophilic inclusions were observed in gamete nuclei. Transmission electron microscopy revealed the presence of viral particles in these intranuclear basophilic inclusions. These particles had characteristics similar to those of the Papillomaviridae and Polyoma viridae families: they were small, non-enveloped, icosahedral, and 44 to 56 nm in diameter. The viral particles were found in male, female and hermaphrodite oysters and no significant difference in viral infection was observed between those groups. The frequency of detection and the intensity of infection were low and no host defence reaction was recognised, suggesting that the viral particles had a weak impact on C. gigas. The viral particles described in the present study seem to be similar to these described in C. virginica in the USA and Canada and in C. gigas in Korea, but further studies are required to confirm their identity. The issue of a possible emergence of this infection is discussed.
authors.affiliation: Laboratoire de Génétique et de Pathologie, IFREMER, Station de La Tremblade, Ronce les Bains, BP 133, 17390 La Tremblade, France. celine.garcia@ifremer.fr
authors.forename: Céline
authors.initials: C
authors.lastname: Garcia
authors.forename: Maeva
authors.initials: M
authors.lastname: Robert
authors.forename: Isabelle
authors.initials: I
authors.lastname: Arzul
authors.forename: Bruno
authors.initials: B
authors.lastname: Chollet
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Joly
authors.forename: Laurence
authors.initials: L
authors.lastname: Miossec
authors.forename: Thierry
authors.initials: T
authors.lastname: Comtet
authors.forename: Franck
authors.initials: F
authors.lastname: Berthe
mesh_terms: D000818:Animals; D049896:Crassostrea / Q000821:virology*; D005260:Female; D005602:France; D005854:Germ Cells / Q000473:pathology / Q000821:virology; D008297:Male; D009865:Oocytes / Q000821:virology; D013094:Spermatozoa / Q000473:pathology / Q000821:virology; D014780:Viruses / Q000302:isolation & purification* / Q000472:pathogenicity* / Q000648:ultrastructure