An Overview of Erythrocytic Iridoviruses in Reptiles and First Molecular Characterization of an Erythrocytic Iridovirus
Erythrocytic inclusions ultrastructurally consistent with iridoviruses have been identified in reptiles, amphibians and fish. In reptiles, these inclusions were formerly misidentified as parasitic protozoa and named Toddia sp. and Pirhemocyton sp. Clinically significant anemia has been documented in association with erythrocytic viruses in several squamate species, and experimental infections have been fatal.1,2 These viruses have never been further characterized. A wild peninsula ribbon snake (Thamnophis sauritus sackenii) in Florida was found to have hypochromic erythrocytes containing two different types of inclusions: purple granular inclusions, and pale crystalline inclusions that were round or rectangular in shape. Transmission electron microscopy revealed homogenous albuminoid vacuoles and enveloped particles morphologically consistent with a member of the Iridoviridae. Histopathology of the animal revealed necrotizing hepatitis. Consensus polymerase chain reaction (PCR) was used to amplify a region of iridoviral DNA-dependent DNA polymerase for sequencing. Bayesian and maximum likelihood phylogenetic analysis found that this virus was distinct from other known iridoviral genera and species and may represent a novel genus and species.
1. Alves de Matos AP, et al. Experimental infection of lacertids with lizard erythrocytic viruses. Intervirology. 2002;45,150–159.
2. Paperna I, Alves de Matos AP. Erythrocytic viral infections of lizards and frogs: new hosts, geographical locations and description of the infection process. Annales de Parasitologie Humaine et Comparee. 1993;68,11–23.