Foot-and-mouth disease virus (FMDV), by nature of its RNA genome, possesses a high rate of mutation during replication. This results in extensive genetic polymorphism of virus populations in nature. The emergence of FMDV variants during replication has been reported. Genetic changes in the viral capsid protein (VP1) gene can result in amino acid changes affecting the immunodominant epitopes of FMDV. The genetic heterogeneity of FMDV in the field and the antigenic variants observed after cell culture isolation has been investigated by PCR sequencing and reactivity with monoclonal antibodies. These methods were applied to viruses causing two different outbreaks of FMD before and after replication in cell culture and in the animal host. The VP1 region of the genome was amplified by PCR and sequenced to reveal variant sequences identified after passage and to determine their presence in the original field tissue. In one case, reactivity with monoclonal antibodies was lost after passage as a result of an amino acid change in the subpopulation. These findings suggest that host cells can select specific virus genetic and antigenic subpopulations during virus isolation and propagation.
Bibliographical noteFunding Information:
We would like to thank Drs. C. Brown, J. House, and D. Gregg for their help with animal inoculationsa nd tissue collection, and Dr. D. Moore for help with computer graphicsa nd submissiono f sequencest o GenBank. Thanks to Drs. F. Brown, L. France, P. Mason, L. Capucci, C. Rossi and F. De Simone for stimulatingd iscussionso n FMDV genetic and antigenicv ariation. We are also gratefult o Prof. S. Barei for his encouragemenat nd to Gino Spagnolif or technical assistanceF. . Simona and G. Donini were supportedb y a fellowship from Fon-dazione Iniziative e Zooprofiletticheo f Brescia.
- Foot-and-mouth disease virus
- Genetic variation
- Polymerase chain reaction