Total nucleic acids were extracted from rat sera or synovium, using the NucleoSpin Tissue kit from Macherey Nagel, following the manufacturer’s protocol. The presence of adenovirus and baculovirus DNA genomes in the rat sera and synovium were then evaluated by PCR using primers specific for each virus. For the HAdV5, the forward primer 5′-GCTGTATTTGCCCGAC-3′ and reverse primer 5′-CATGGCCTCAAGCGTG-3′, amplified a fragment of 465 nt of the hexon gene. For the baculovirus, the forward primer 5′-GCTGTATTTGCCCGAC-3′ and reverse primer 5′-CATGGCCTCAAGCGTG-3′, amplified a fragment of 1095 nt of the baculovirus-CAR gene.