The foot-and-mouth disease virus (FMDV) causes a highly infectious disease of all cloven-footed animals. The RNA genome of the virus continuously evolves, leading to the generation of new strains; this necessitates the selection of new vaccine strains to ensure complete protection. Infection with one FMDV serotype does not provide cross-protection against the other FMDV serotypes. Many of the recovered animals may become carriers of the FMDV, but they still remain susceptible to the other serotypes. Coinfection with multiple FMDV serotypes has been reported and studied to understand the virus evolution. Isolation and characterization of all the involved serotypes in the mixed infection case is essential to understand the molecular evolution of the virus. In this study, two cases of coinfection were studied by selective isolation of each of the FMDV serotypes under the cross-serotype-specific immune pressure. It was estimated that the virus present in a minimum of 10^−0.92 TCID₅₀ could be isolated from the mixed population containing other serotypes in infective doses of 10^0.25 TCID₅₀ or less. All involved serotypes present in the mixed infection cases were isolated, without any cross-contamination. Virus characterization revealed that genotype 2 was of serotype A virus from a sample collected in 1995, which was last reported in 1986, indicating a possible subdued prevalence of the genetic group even after vanishing from the field.

口蹄疫病毒 (FMDV) 会引起所有偶蹄动物的高度传染性疾病。病毒的RNA基因组不断进化，导致新毒株的产生；这需要选择新的疫苗株以确保完全保护。感染一种 FMDV 血清型不会提供针对其他 FMDV 血清型的交叉保护。许多恢复的动物可能成为口蹄疫病毒的携带者，但它们仍然对其他血清型易感。已报告并研究了多种 FMDV 血清型的共感染以了解病毒的进化。混合感染病例中所有相关血清型的分离和表征对于了解病毒的分子进化至关重要。在这项研究中，通过在交叉血清型特异性免疫压力下选择性分离每种 FMDV 血清型，研究了两例合并感染病例。据估计，该病毒至少存在于 10^-0.92 TCID ₅₀可以从包含其他血清型的混合群体中以 10 ^0.25 TCID ₅₀或更低的感染剂量分离。混合感染病例中存在的所有相关血清型均被隔离，没有任何交叉污染。病毒特征表明，基因 2 是 1995 年收集的样本中的血清 A 型病毒，最后一次报告是在 1986 年，这表明该基因组的流行率即使在从田间消失后也可能有所减弱。