Characteristic in vitro evolution pattern of foot and mouth disease virus A81/Castellanos/Arg/87.

The in vitro evolution of Foot and mouth disease virus (FMDV) A/81/Castellanos/Arg/87 (A/Castellanos/87) was studied by partial biological and biochemical characterization of viral populations selected after 25 passages on secondary fetal bovine kidney cell monolayers. These passages were performed in the presence or absence of immune pressure exerted in the form of antiviral polyclonal serum. While the viral populations passaged in the absence of immune pressure acquired characteristics such as antigenic heterogeneity, VP1 amino acid modification and plaque size reduction, the populations selected after immune pressure also presented both neutralizing resistance and attenuation for suckling mice. The comparison with other previously studied FMDV strains suggests that FMDV A/Castellanos/87 adopts a differential response to immunological pressure and other selective forces. In addition, the sequencing analysis of viral selected populations shows a restriction in the number and type of amino acid replacements tolerated by FMDV capsid proteins.