Reptilia-related viruses

Viruses in reptiles

The etiology of reptilian viral diseases can be attributed to a wide range of viruses occurring across different genera and families. Thirty to forty years ago, studies of viruses in reptiles focused mainly on the zoonotic potential of arboviruses in reptiles and much effort went into surveys and challenge trials of a range of reptiles with eastern and western equine encephalitis as well as Japanese encephalitis viruses. In the past decade, outbreaks of infection with West Nile virus in human populations and in farmed alligators in the USA has seen the research emphasis placed on the issue of reptiles, particularly crocodiles and alligators, being susceptible to, and reservoirs for, this serious zoonotic disease. Although there are many recognised reptilian viruses, the evidence for those being primary pathogens is relatively limited. Transmission studies establishing pathogenicity and cofactors are likewise scarce, possibly due to the relatively low commercial importance of reptiles, difficulties with the availability of animals and permits for statistically sound experiments, difficulties with housing of reptiles in an experimental setting or the inability to propagate some viruses in cell culture to sufficient titres for transmission studies. Viruses as causes of direct loss of threatened species, such as the chelonid fibropapilloma associated herpesvirus and ranaviruses in farmed and wild tortoises and turtles, have re-focused attention back to the characterisation of the viruses as well as diagnosis and pathogenesis in the host itself.

1. Introduction

2. Methods for working with reptilian viruses

3. Reptilian viruses described by virus families

3.1. Herpesviridae

3.2. Iridoviridae

3.2.1 Ranavirus

3.2.2 Erythrocytic virus

3.2.3 Iridovirus

3.3. Poxviridae

3.4. Adenoviridae

3.5. Papillomaviridae

3.6. Parvoviridae

3.7. Reoviridae

3.8. Retroviridae and inclusion body disease of Boid snakes

3.9. Arboviruses

3.9.1. Flaviviridae

3.9.2. Togaviridae

3.10. Caliciviridae

3.11. Picornaviridae

3.12. Paramyxoviridae

4. Summary

5. Acknowledgements

6. Competing interests

7. References

Three novel herpesviruses associated with stomatitis in Sudan plated lizards (Gerrhosaurus major) and a black-lined plated lizard (Gerrhosaurus nigrolineatus)

Glossal stomatitis was observed in a Sudan plated lizard (Gerrhosaurus major) with severe dyspnea. On necropsy, intranuclear inclusion bodies were seen in the periglottal lingual epithelium. Labial stomatitis was seen in a second Sudan plated lizard and a black-lined plated lizard (G. nigrolineatus). Degenerate polymerase chain reaction (PCR) primers targeting a conserved region of herpesvirus DNA-dependent DNA polymerase gene were used to amplify products from lesions from each lizard. Nucleotide sequencing of the PCR products showed that the sequence from each lizard was unique. Phylogenetic and comparative sequence analyses suggest that these viruses are novel members of the subfamily Alphaherpesvirinae, and they are here termed gerrhosaurid herpesviruses 1-3. Results of our analyses suggest that the genus Gerrhosaurus can be infected by these novel herpesviruses.

The diversity and unity of Herpesviridae

The family herpesviridae contains over 100 viruses endogenous to humans and to a wide variety of eukaryotic organisms. Inclusion in the family is based on architecture of the virion. The viruses differ significantly with respect to base composition and sequence arrangements of their DNAs, but share many biologic properties including the ability to remain latent in their hosts. On the basis of their biologic properties the herpesviruses have been classified into three subfamilies, i.e. alphaherpesvirinae, betaherpesvirinae and gammaherpesvirinae. The members of each subfamily share many properties including greater conservation and colinear arrangements of their genes. As a rule, more than one herpesvirus has been isolated from animals of economic importance and both humans have yielded viruses belong to all three subfamilies of the herpesviridae.

Isolation of a reovirus from the snake, Python regius. Brief report

A reovirus isolated from a moribund snake was not neutralized by antisera against mammalian serotypes, did not agglutinate human O erythrocytes, and produced fusion of IgH 2 cells. The genome contained 10 segments of dsRNA.

Restriction endonuclease analysis of mitochondrial DNA from virus-transformed, tumor and control cells of human, hamster and avian origin. Sequence conservation and intraspecific variation

This study compares over 70 recognition sites for restriction endonucleases on mtDNAs from various control versus malignant cells, derived from Syrian hamster, chick embryo, viper and human cells, exhibiting a wide spectrum of cellular transformation and tumor histories. Agents for transformation in vitro and in vivo include Rous sarcoma viruses, simian virus 40, polyoma virus and adenovirus. The results show a striking intraspecific sequence homogeneity of different mtDNAs regardless of tissue origin and oncogenic history. mtDNA from human biopsy specimens of tumor versus pathologically normal areas yielded indistinguishable restriction cleavage patterns reflecting either the "wild-type' form (with seven restriction endonucleases) or, in one individual, a variant pattern detected with HpaI. The precise position of the HpaI variant site was determined on the physical map of human mtDNA. Additional cleavage sites in the previously reported restriction map of Syrian hamster mtDNA are also presented. It is concluded that (1) mtDNA sequence in higher animal cells are highly conserved in malignant transformation; (2) no evidence for integration of viral sequences in mtDNA is apparent; (3) variant patterns in mtDNA are likely to be intraspecific polymorphisms that pre-exist neoplastic transformation. The possibility is discussed that altered regulatory interaction with the mitochondrial genome, rather than evident changes in mtDNA primary structure, determine anomalous mitochondrial functions in malignant transformation.