Rabbit haemorrghagic disease: new types of virus on our territory?

Rabbit haemorrghagic disease (RHD) is highly contagious and acute fatal hepatitis of the European rabbit (Oryctolagus cuniculus). This disease is widespread throughout the world and is characterized by a high number of deaths in affected animals. Preventive vaccination against RHD has contributed to a significant reduction in losses also in the Czech Republic. Rabbit haemorrghagic disease virus (RHDV) is currently present in several mutually different antigenic variants-RHDV (the original variant and the oldest one), RHDVa (newer variant) and RHDV2 (the latest variant). The clinical disease caused by RHDV2, unlike the RHDV and RHDVa, has lower lethality–infected rabbits may begin to die since the 15th day of age. The vaccines containing RHDV and RHDVa do not protect the rabbits against RHDV2 infection. The virus cannot be cultivated in cell cultures. Therefore we did virus detection and genotyping of viral variants by real time RT-PCR and sequencing. Using genotyping, it was found that all viral strains received from Collection of Animal Pathogenic Microorganisms (CAPM VÚVeL v.v.i., Brno, Czech Republic) belong to RHDV. We have proven that Czech RHDV strains from 1988 –1992 belong to the genotype G2 as well as the foreign strains coming from the same time period. On the contrary, the Czech strains from 1994 –1996 are ranked to genotypes G3 –G5.However, none of them has been detected at present. We have demonstrated two different subtypes of RHDV (RHDVa –two strains and RHDV2-six strains) in the liver of the dead rabbits coming from different regions of the Czech Republic. Phylogenetic analysis showed that individual RHDV2 strains can be divided into two clusters, which differ slightly by geographic distribution. Compared to RHDVa, the RNA concentration of RHDV2in the liver tissue of dead rabbits was significantly higher. But, in dead non-vaccinated pups the highest RNA concentration was found in the spleen, not in the liver. Because the vaccine used so far against RHDV does not have the required protective effect against RHDV2, we recommend adding RHDV2to the vaccination scheme.Submitting country: Czech Republic; Language: Czech; Contact: efsa.focalpoint@mze.c