Fig. 6.

The characterization of the GA-derived chimeric virus. (A) vRNAs were extracted from RespPRRSV (Resp), Hun4 F112 (Hu), or the GA-derived chimeric virus (Chi). Primers specific for a small region of F1 were used to obtained DNA products representing the 5′ end of the genome, and primers specific for a small region of F4 were used to generate DNA products representing the 3′ end of the genome. 5′ end products were digested with AatII and NaeI, while 3′ end products were digested with EcoRV and NruI. Undigested and digested products were analyzed on a 1% agarose gel. (B and C) MARC-145 cells were infected with RespPRRSV (Resp), Hun4 F112 (Hu), or the GA-derived chimeric virus (Chi). (B) The infected cells were overlaid with medium containing 0.9% agar. On day 4 post-infection, the cells were stained with cystal violet, and plaque sizes were documented. (C) Culture supernatants were collected every 24 h post-infection and the virus titers were measured by plaque assay.