These lineages come to be known as strains. If enough mutations accumulate in a lineage, the viruses may evolve clear-cut differences in how they function. If enough mutations accumulate in a lineage, the viruses may evolve clear-cut differences in how they function. These lineages come to be known as strains. These lineages come to be known as strains. If enough mutations accumulate in a lineage, the viruses may evolve clear-cut differences in how they function.。
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