Comparisons of the complete genomes of Asian, African and European isolates of a recent foot-and-mouth disease virus type O pandemic strain (PanAsia)

During the last 12 years, a strain of foot-and-mouth disease (FMD) virus serotype 0, named PanAsia, has spread from India throughout Southern Asia and the Middle East. During 2000, this strain caused outbreaks in the Republic of Korea, Japan, Russia (Primorsky Territory), Mongolia and South Africa (KwaZulu-Natal Province), areas which last experienced FMD outbreaks in 1934, 1908, 1964, 1974 and 1957, respectively. In February 2001, the PanAsia strain spread to the United Kingdom where, in just over 7 months, it caused outbreaks on 2030 farms. From the UK, it quickly spread to the Republic of Ireland, France and the Netherlands. Previous studies that utilized RT-PCR to sequence the VP1-coding region of the RNA genomes of approximately 30 PanAsia isolates demonstrated that the UK virus was most closely related to the virus from South Africa (99.7% nucleotide identity). To determine if there was an obvious genetic reason for the apparently high level of fitness of this new strain, and to further analyse the relationships between the PanAsia viruses and other FMDVs, complete genomes were amplified using long-range PCR techniques and the PCR products were sequenced, revealing the sequences for the entire genomes of five PanAsia isolates as well as an animal-passaged derivative of one of them. These genomes were compared to two other PanAsia genomes. These analyses revealed that all portions of the genomes of these isolates are highly conserved and provided confirmation of the close relationship between the viruses responsible for the South Africa and UK outbreaks, but failed to identify any genetic characteristic that could account for the unprecedented spread of this strain.