Description of the first haemocytic rod-shaped virus from a penaeid prawn

Abstract

Epizootic losses of hybrid Penaeus esculentus by P. monodon crosses initiated an electron microscopical investigation. A haemocytic rod-shaped virus was found in the gill tissues as well as infectious hypodermal and haematopoietic necrosis virus in other tissues (reported elsewhere). Within the cytoplasm of small-granule haemocytes and the nucleus of other unrecognised cells, rod-shaped virions were present. The virions were 588 x 119 nm with extraordinarily long virions being 888 nm. Some were encapsulated by a smaller envelope which forced the long virions to become either V- or U-shaped. Empty capsids 496 x 50 nm were also seen in the nucleoplasm. Capsid originators were 50 to 60 nm long. The virus is named penaeid haemocytic rod-shaped virus (PHRV) until its relationship to other haemocytic viruses can be ascertained. However, PHRV showed affinities to the genus Bracovirus within the Polydnaviridae and the size and morphology were somewhat similar to rod-shaped virus of Carcinus maenus (RV-CM).