Myxomatosis and rabbit haemorrhagic disease (RHD) are two viral diseases affecting the European rabbit. Both are almost invariably fatal in the naive animal; therefore, there is a real need for safe and efficacious vaccines against both of these diseases.

Vaccination against myxomatosis has been practiced for some time. Vaccines are based on a closely related poxvirus (Shope fibroma virus) or on attenuated strains of myxoma virus. Each has its advantages and disadvantages. Shope based vaccines may be considered less immunogenic and provide only short term protection, whereas attenuated myxoma vaccines may be immunosuppressive, particularly in young rabbits. Such immunosuppression in animals held in large rabbitries can lead to serious problems of bacterial respiratory infection.

Vaccines against RHD currently consist of inactivated, adjuvanted virus preparations derived from infected rabbit livers. These products are able to stimulate effective immune responses; however, the adjuvants may sometimes cause unwanted site reactions, particularly in dwarf and show animals.

Here we show that a live attenuated myxoma virus expressing the capsid protein of RHDV is able to provide protection against both myxomatosis and RHD following challenge 1 year post vaccination.

A group of 20 rabbits were given a single vaccination of Nobivac Myxo-RHD, in a volume of 1.0 ml administered by the sub-cutaneous route, a second group of 10 unvaccinated rabbits were kept as controls.

At 12 months post vaccination, 5 control animals and 10 vaccinated animals were challenged with myxoma virus. All 5 controls died or had to be euthanised as a result of the challenge; all vaccinated animals survived. Six of the 10 challenged vaccinated rabbits showed no clinical signs whatsoever, 3 of the remaining 4 showed some transient minor signs which were indicative of an active anti myxoma immune response. The fourth vaccinated rabbit exhibited a transient ocular discharge which was unlikely to be attributable to the challenge.

At 13 months post vaccination, the remaining control and vaccinated animals were challenged with RHDV. All control animals died or had to be euthanised within 48 hours of challenge, whereas all vaccinated animals survived challenge and did not show any signs of disease.

We demonstrate here that a novel, live, myxoma-vectored RHDV vaccine provides comprehensive protection against both myxomatosis and RHD one year after a single subcutaneous injection.