Experimental Infection of Lacertids with Lizard Erythrocytic Viruses

Abstract

Objective: Lizard erythrocytic viruses (LEVs) produce inclusions in the cytoplasm of erythrocytes, but their impact on the infected host is poorly understood. This work reports on an experimental study of the infection process in Lacerta monticola and Lacerta schreiberi from Serra da Estrela Mountain, Portugal. Methods: A time sequence light microscope and transmission electron microscope (TEM) study of the infection process was performed in peripheral blood erythrocytes of experimentally infected lizards. Virions were searched for by TEM in visceral organs and bone marrow of the animals. Results: Infection was usually restricted to erythrocytes, but occasionally became systemic and induced disease. In the first case, a prevalence of infected erythrocytes of up to 98% followed by recovery was observed. In the latter, infection spread to leukocytes, leading to the death of the infected animals. Conclusions: The potential of LEVs to induce systemic infections was demonstrated. Sequential TEM examination of LEV-infected cells is described for the first time, demonstrating features such as dense inclusions related to virus nucleoid formation, intranuclear virions, intermediate structures in virion capsid morphogenesis and virus release by budding.

Intraerythrocytic iridovirus in central bearded dragons (Pogona vitticeps)

“…18,26 In some cases, erythrocytic inclusions have been associated with marked anemia, 17,26 but experimental infection has failed to reproduce anemia unless the lizards were maintained in a cold environment. 3 Many viral diseases of poikilothermic vertebrates are highly temperature dependent, including iridoviruses, and the current data does not differentiate among the relative roles of host and virus on temperature-dependence of disease. 19,30 Therefore, the pathogenicity of EIVs in reptiles is not well defined.…”

Viruses Infecting Reptiles

“…Pathology associated with erythrocytic necrosis virus infections in reptiles is unclear, but morphological changes in infected erythrocytes have been documented. A transmission study conducted with the lizards Lacerta monticola and Lacerta schreiberi showed that infection with these agents can, in some cases, become systemic and may lead to death [37]. Recently, a PCR was successfully used to detect an iridovirus in a ribbon snake with erythrocytic inclusions in Florida, USA.…”

Lizards

“…52 Marschang et al isolated irido-like viruses of two different genera, Iridovirus and Ranavirus, from a four-horned chameleon, a green iguana, and a leaf-tailed gecko (Uroplatus fi mbriatus). 55 However, in some instances the virus infected leukocytes and killed the infected animals. 53 Lizard erythrocytic viruses (LEVs) have been described under the family Iridoviridae 54 and their pathogenicity (e.g., LEVs) is poorly understood.…”

“…53 The genus Iridovirus had been described in insects but not reptiles, which suggests the possibility of transmission of iridoviruses from insects to reptiles. 55 Other reports of LEVs include nine fl ap-necked chameleons (Chamaeleo dilepis), 54 one Fischer's chameleon (Bradypodion fi scheri), 54 two four-horned chameleons, 56 and a high-casqued chameleon (Chamaeleo hoehnelli). Alves de Matos et al performed an experimental infection of two lizard species (Lacerta monticola and Lacerta schreiberi) and demonstrated that the infection was mostly restricted to erythrocytes.…”