Boid inclusion body disease (BIBD) is a fatal disorder of boid snakes that is suspected to be caused by a retrovirus. In order to identify this agent, leukocyte cultures (established from Python molurus specimens with symptoms of BIBD or kept together with such diseased animals) were assessed for reverse transcriptase (RT) activity. Virus from cultures exhibiting high RT activity was banded on sucrose density gradients, and the RT peak fraction was subjected to highly efficient procedures for the identification of unknown particle-associated retroviral RNA.

A 7-kb full retroviral sequence was identified, cloned, and sequenced. This virus contained intact open reading frames (ORFs) for gag, pro, pol, and env, as well as another ORF of unknown function within pol. Phylogenetic analysis showed that the virus is distantly related to viruses from both the B and D types and the mammalian C type but cannot be classified. It is present as a highly expressed endogenous retrovirus in all P.

Molurus individuals; a closely related, but much less expressed virus was found in all tested Python curtus individuals. Burgmuller Op 109 Pdf Writer on this page. All other boid snakes tested, including Python regius, Python reticulatus, Boa constrictor, Eunectes notaeus, and Morelia spilota, were virus negative, independent of whether they had BIBD or not. Virus isolated from P. Molurus could not be transmitted to the peripheral blood mononuclear cells of B. Constrictor or P. Thus, there is no indication that this novel virus, which we propose to name python endogenous retrovirus (PyERV), is causally linked with BIBD.

Retroviruses were identified in snakes more than 30 years ago, when C-type-like particles were observed by electron microscopy in the tissues of a tumor-bearing viper (-) and were later shown to be related to primate D-type retroviruses (). Retrovirus-like particles subsequently detected in snakes also involved mostly animals affected with proliferative disorders (,, ) but were also found in normal tissues (). Recently, a systematic PCR-based search for endogenous retroviruses related to murine leukemia virus (MLV) showed a widespread distribution of such C-type sequences among terrestrial animals, including amphibians, reptiles, birds, and mammals (). In 1994, a retrovirus responsible for boid inclusion body disease (BIBD) in snakes, a disease known for more than 20 years to occur in snakes of both the Boinae and Pythoninae subfamilies of Boidae, was described in private and zoological snake collections all over the world (,, ). Clinical signs of BIBD include chronic regurgitation and central nervous system (CNS) disease manifested in head tremors, disorientation, lack of motor coordination, paresis, and/or paralysis. Histologic examination revealed numerous eosinophilic intracytoplasmic inclusion bodies in the epithelial cells of all major organs, including neurons within the CNS.