Molecular epidemiology of classical swine fever in Cuba

The origin and evolution of the classical swine fever (CSF) epizootic that occurred in Cuba from 1993 to 1997 has been investigated by the analysis of E2 gene sequences from 15 representative viral isolates as well as the vac cine and the challenge strains used in this country. In the phylogenetic tr ee derived from these sequences, the Cuban isolates were located in a defin ed cluster within the previously reported genomic subgroup 1.2. This cluste r was related, although distinguishable, from the live vaccine used in Cuba since 1965. Two further groups were identified. One of them included the e arly viruses isolated in the western part of Cuba until 1996 and the strain Margarita, used for vaccine potency tests since 1965. These results are co nsistent with the strain Margarita being the origin of the western outbreak s. The viruses isolated from 1996 in eastern Cuba defined a related, but in dependent group. The level of sequence variation observed in this group doe s not exclude an independent origin for the eastern isolates. (C) 1999 Else vier Science B.V. All rights reserved.