Marine Biodiversity Records

Research Article

Suspected viral erythrocytic necrosis (VEN) in a juvenile blackbar triggerfish, Rhinecanthus aculeatus, from Lizard Island, Great Barrier Reef, Australia

Angela J. Daviesa1a2 c1, Lynda Curtisa3, Alexandra S. Gruttera3 and Nico J. Smita2

a1 School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, UK

a2 Department of Zoology, University of Johannesburg, Auckland Park, Johannesburg, South Africa

a3 School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia

Abstract

Suspected viral erythrocytic necrosis (VEN) was detected in blood films from an immature blackbar triggerfish, Rhinecanthus aculeatus, captured on a patch reef at Lizard Island, Great Barrier Reef in November 2005, probably the first record of such an infection from Australia. The fish was kept in captivity and sampled intermittently until December 2007. Giemsa-stained blood films showed initially ~18% of mature erythrocytes affected by the VEN-like condition, but accompanying erythroblasts appeared free from infection. Erythrocytes with VEN-like bodies were smooth or crenated in outline, while the inclusion bodies were intracytoplasmic, single or paired, round in outline, stained deep magenta and were between 0.5–1.7 μm across. Bodies associated with clouds of granular material, fine eosinophilic haloes, and distinct pink-stained comet-tails, were also observed. The DNA content of the VEN-like bodies was confirmed by their green fluorescence following acridine orange staining. Infection levels in this fish fell to 0.4% of mature erythrocytes by May 2006 and persisted at this level until December 2007, when the fish died after just over two years in captivity. Squashes of haematophagous, juvenile gnathiid isopods taken from this fish on initial capture, also contained eosinophilic VEN-like bodies within digesting erythrocytes, suggesting that these crustaceans may be vectors of the condition observed.

(Received April 14 2009)

(Accepted July 02 2009)

Keywords

  • suspected viral erythrocytic necrosis (VEN);
  • blackbar triggerfish;
  • Rhinecanthus aculeatus;
  • Great Barrier Reef

Correspondence:

c1 Correspondence should be addressed to: A.J. Davies, School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, UK email: ajdavies.russell@kingston.ac.uk