Paramyxovirus Infection in Snakes

Matthew A. Sand; Kathryn G. Smith; Christopher R. Gregory, DVM, PhD; Branson W. Ritchie, DVM, PhD; and Kenneth S. Latimer, DVM, PhD

Undergraduate Honors Microbiology Program (Sand), and Undergraduate Honors Biology Program (Smith), The University of Georgia, Athens, GA 30602; Department of Small Animal Medicine (Gregory, Ritchie) and Department of Pathology (Latimer), College of Veterinary Medicine, The University of Georgia, Athens, GA 30602

In 1972, a disease outbreak characterized by respiratory distress, lethargy, and death occurred on a snake farm in Zurich, Switzerland.¹ A virus subsequently was isolated from lung tissue of one of the dead snakes. This virus initially was classified as a paramyxo-like virus and designated Fer-de-Lance Virus (Fig. 1). Since the original disease outbreak and identification of a viral etiology in 1972, ophidian paramyxoviruses (OPMV) have emerged as important pathogens of viperid snakes.

Fig. 1. Fer-de-Lance, the species of snake in which ophidian paramyxovirus infection was originally described and diagnosed.

The first report of OPMV infection in the United States occurred in 1980 in a private collection of snakes in Florida.² In a second outbreak, OPMV was isolated from snakes that died at a Louisiana Zoo.³ Similar viruses also have been isolated from non-viperid snakes including a black mamba, corn snakes, beauty snakes, and Moellendorff’s rat snakes.⁴ Clinical signs of OPMV include a sudden gaping of the mouth, followed by violent convulsions, regurgitation, and expulsion of a brownish fluid from the glottis. Death usually follows within hours of the first convulsion. A variety of lesions have been described in snakes dying with OPMV infections, including proliferative pneumonia, encephalitis, and pancreatic hyperplasia.

Paramyxoviruses are single-stranded RNA viruses of the family Paramyxoviridae. Members of this viral family not only cause respiratory disease (influenza), but also may produce neurological disease (such as canine distemper in dogs). Diagnosis of paramyxovirus infection in snakes has involved a variety of techniques including routine histology, immunohistochemistry, fluorescent antibody staining, hemagglutination inhibition, and virus isolation with molecular characterization.^5-8

The goal of this research project is to develop sensitive and specific molecular methods to diagnose paramyxovirus infection in snakes. The first objective is to develop molecular probes for the post mortem diagnosis paramyxovirus infection in formalin-fixed, paraffin embedded tissue specimens. The second objective is to develop an antemortem diagnostic test to detect paramyxovirus in biological specimens using the reverse transcriptase – polymerase chain reaction (RT-PCR) technique (Fig. 2).

Fig. 2. Digital image of an agarose gel demonstrating the presence of an RT-PCR product (arrow at lane 5) amplified from ophidian paramyxovirus-infected tissues.  The molecular marker is at lane 1; negative controls are at lanes 2-4.

References

1. Clark HF, Leif FS, Lunger PD, Waters D, Leloup P, Foelsch DW, Wyler RW: Fer de Lance virus (FDLV): a probable paramyxovirus isolated from a reptile. J Gen Virol 44:405-418, 1979.

2. Jacobson E, Gaskin JM, Simpson CF, Terrell TG: Paramyxo-like virus infection in a rock rattlesnake. J Am Vet Med Assoc 177:796-799, 1980.

3. Jacobson E, Gaskin JM, Page D, Iverson WO, Johnson JW: Illness associated with paramyxo-like virus infection in a zoologic collection of snakes. J Am Vet Med Assoc 179:1227-1230, 1981.

4. Jacobson E, Gaskin JM, Wells S, Bowler K, Schumacher J: Epizootic of ophidian paramyxovirus in a zoological collection: Pathological, microbiological, and serological findings. J Zoo Wildlife Med 23:318-327, 1992.

5. Jacobson ER, Adams HP, Geisbert TW, Tucker SJ, Hall BJ, Homer BL: Pulmonary lesions in experimental ophidian paramyxovirus pneumonia of Aruba Island rattlesnakes, Crotalus unicolor. Vet Pathol 34:450-459, 1997.

6. Homer BL, Sundberg JP, Gaskin JM, Schumacher J, Jacobson ER: Immunoperoxidase detection of ophidian paramyxovirus in lung using a polyclonal antibody. J Vet Diagn Invest 7:72-77, 1995.

7. Richter GA, Homer BL, Moyer SA, Williams DS, Scherba G, Tucker SJ, Hall BJ, Pedersen JC, Jacobson ER: Characterization of paramyxoviruses isolated from three snakes. Virus Res 43:77-83, 1996.

8. Ahne W, Batts WN, Kurath G, Winton JR: Comparative sequence analysis of sixteen reptilian paramyxoviruses. Virus Res 63:65-74, 1999

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