Isolation and molecular characterization of a second serotype of the encephalomyelitis virus
Encephalomyocarditis virus (EMCV) and Theilovirus are the two species of the Cardiovirus genus. Whereas theiloviruses comprise several sero-/genotypes, all known EMCV isolates are serologically very similar and are thought to belong to one serotype, named EMCV-1. Here, a novel EMCV type is described. Strain RD 1338 (D28/05) was isolated from a wood mouse (Apodemus sylvaticus) in Germany and can be distinguished from EMCV-1 by serological and molecular means. Failure of EMCV-1 specific hyperimmune sera to neutralize RD 1338 suggests a distinct serotype. The viral genome was de novo sequenced using next-generation Illumina/Solexa technologies. Considerable differences of the BC-loop/loop I/loop II sequences of VP1, the VP2 puff and the VP3 knob provide a structural basis for deviant serological properties. Sequence alignments reveal amino acid identities of 75 percent for the P1 region and 84 percent for the P2 and P3 regions when comparing RD 1338 to EMCV-1 strains and some 60 percent and less than 50 percent amino acid identities, respectively, for comparisons with theilovirus strains. Phylogenetic analyses of the P1, 2C and 3CD gene regions support the establishment of an EMCV-2 serotype. In contrast to the theilovirus sero-/genotypes that show a narrow host range, EMCV-1 infects a wide variety of hosts. The host range of EMCV-2 remains to be determined.