Rabbit hemorrhagic disease virus (RHDV)  NOTE: THIS TEST IS NOT PERFORMED ON SAMPLES TAKEN FROM ANIMALS OWNED OR LOCATED IN THE STATE OF CALIFORNIA.

Test code: S0238 - Ultrasensitive qualitative detection of rabbit hemorrhagic disease virus by reverse transcription coupled real time polymerase chain reaction

Rabbit hemorrhagic disease virus (RHDV) is a non-enveloped positive-stranded RNA virus of the genus Lagovirus within family Caliciviridae. The virus is suspected to have evolved from a pre-existing avirulent rabbit calicivirus. Nonpathogenic rabbit caliciviruses are circulating in Europe, Australia, and New Zealand. Because of its close similarity to the nonpathogenic rabbit caliciviruses, serological detection of RHDV is very difficult due to cross-reactivity.

At least five distinct genotypes of RHDV have evolved:

RHDV (classical) only affects adult European rabbits (Oryctolagus cuniculus). This virus was first reported in China in 1984, from which it spread to much of Asia, Europe, Australia, and elsewhere. A few isolated outbreaks of RHDV had been reported in the United States and Mexico, but they remained localized and were eradicated.

RHDV2 has distinctive genetic, antigenic, and pathogenic features. RHDV2 can kill rabbits previously vaccinated with RHDV vaccines, and affects young European rabbits as well as hares (Lepus spp). These features strongly suggest that the virus is not derived from RHDVa or RHDV (classical), but from some other unknown source. RHDV2 has since spread through most of Europe, and to Australia, Canada, and the United States. RHDV2 is highly contagious and, unlike other rabbit hemorrhagic disease viruses, it affects both domestic and wild rabbits. The RHDV2 virus is very resistant to extreme temperatures. It can spread through direct contact or exposure to an infected rabbit’s excretions or blood. The virus can also survive and spread from carcasses, food, water, and other contaminated materials. People can spread the virus indirectly by carrying it on their clothing and shoes. When rabbits are infected with RHDV2, the only signs of the disease may be sudden death and bloodstained noses caused by internal bleeding. Infected rabbits may also develop fever, hesitancy to eat, respiratory symptoms and neurological signs.

These viruses cannot be cultured easily. Detection of antibody against the virus is not specific due to cross reactivity with non-pathogenic rabbit calicivirus (Nagesha et al., 2000). Molecular detection by polymerase chain reaction (PCR) is the preferred diagnostic method due to its high specificity and sensitivity.

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of RHDV infection.
• Help ensure that rabbit colonies and populations are free of this virus
• Early prevention of spread of RHDV among a colony or population
• Minimize human exposure to this virus
• Safety monitoring of biological products that derive from rabbits

References:
Nagesha, H., McColl, K., Collins, B. et al. (2000) The presence of cross-reactive antibodies to rabbit haemorrhagic disease virus in Australian wild rabbits prior to the escape of virus from quarantine. Arch. Virol. 145: 749–757.

Specimen requirements: Oral swab, or fecal pellet, or 0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml fresh or frozen tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative reverse transcription coupled real time PCR

Normal range: Nondetected