Differences in the virulence of two strains of Foot-and-Mouth Disease Virus Serotype A with the same spatiotemporal distribution

During the 2000-2001 epidemic of Foot-and-Mouth Disease Virus (FMDV) in Argentina, two FMDV serotype A viruses were identified among others. Since different pathogenic properties between these virus strains were noticed in cattle, we evaluated several biological properties and features of FMDV A/Arg/00 and FMDV A/Arg/01 in order to compare these viruses in terms of virulence and pathogenicity. Our results indicate that FMDV A/Arg/00 grows less efficiently than FMDV A/Arg/01, exemplified by smaller sized plaques, retarded one-step growth curves and overall low viral yields. Also, FMDV A/Arg/00 displayed the lowest specific infectivity in suckling mice requiring 50-fold more infectious particles than FMDV A/Arg/01 to generate a LD50 in suckling mice. Finally, FMDV A/Arg/00 did not cause death in adult C57Bl/6 mice even at high doses (10(7)-10(6) PFU) whereas FMDV A/Arg/01 resulted lethal in doses as low as 10(2) PFU. Overall, we were able to demonstrate that these virus strains differ from each other in terms of virulence and pathogenicity. (c) 2009 Elsevier B.V. All rights reserved.