To the Editor: During November 2012-February 2013, rabbit hemorrhagic disease virus (RHDV) strains belonging to the new variant RHDV were isolated in Portugal from wild European rabbits (Oryctolagus cuniculus subsp.
These subspecies are equally susceptible to RHDV (3).
Before the new variant of RHDV emerged and, on the basis of phylogenetic relationships, RHDV strains had been divided into 6 genogroups (G1-G6) (1), with strains of G6, or RHDVa, having a distinct antigenic profile (6).
The identification of rabbit caliciviruses (RCVs) (5,6), nonpathogenic viruses antigenetically similar to RHDV, and recent descriptions of a pathogenic RCV (7), an RHDV variant grouping with RCV viruses in phylogenetic analysis (8), and nonpathogenic RHDV (9) raise questions about the origins, classification, and nomenclature of these viruses.
Macroscopic lesions in infected kits were consistent with RHDV infection usually observed only in adult rabbits (4).
Carlsbad, CA, USA), LA-Taq polymerase (Takara Bio, Otsu, Japan), and forward and reverse primers annealing at nt 6056-6075 and 6775-6794, respectively (positions refer to the genomic sequence of RHDV Ast/89; GenBank accession no.
After blocking with milk diluted in phosphate-buffered saline, RHDV strains isolated from whole liver extracts of infected animals were incubated on coated plates at dilutions corresponding to 1 x [10.
Human saliva samples were recognized by 5 of 6 RHDV strains.
GenBank accession numbers for complete and partial rabbit caliciviral nucleotide sequences used for phylogenetic analysis are as follows: RHDV strains USA IA00 (AF258618), USA UT01 (EU003582), USA NY01 (EU003581), USA IN05 (EU003579), JX China 97 (DQ205345), China CD (AY523410), China WHNRH (DQ280493), Italy 90 (EU003580), Germany FRG (NC001543), China WX84 (AF402614), Mexico 89 (AF295785), Spain AST89 (Z49271), Ireland 18 (DQ367359), Italy BS89(X87607), EBHSV (NC002615), RCV (X96868), MRCV (GQ166866).
The rabbits were free of Pasteurella multocida, Bordetella bronchiseptica, Encephalitozoon cuniculi, Treponema cuniculi, Clostridium piliforme, myxomatosis virus, RHDV, Toxoplasma spp.
Since 2012, the new variant of RHDV has been detected in most rabbit farms in Spain (6), and in several wild populations distributed across Spain and Portugal (7), suggesting that it has rapidly spread throughout the Iberian Peninsula.
On the other hand, the number of lynxes killed on roads doubled in 2013 (n = 14) in relation to 2012 (n = 7), and this has been linked to increased lynx displacements related to rabbit scarcity potentially associated with the impact of the new variant of RHDV (http://www.