Concurrent porcine circovirus type 2a (PCV2a) or PCV2b infection increases the rate of amino acid mutations of porcine reproductive and respiratory syndrome virus (PRRSV) during serial passages in pigs.

Highlights: [•] The genetic variability of PRRSV during serial passage in PCV2-infected pigs was investigated. [•] PRRSV structural genes ORF6 and ORF7 mutated at various degrees over time in vivo. [•] A significantly higher mutation rate was observed when pigs were co-infected with PCV2. [Copyright &y& Elsevier]