FIG 1.

Schematic representation of WT PR8 H1N1 virus, Ms virus, and NSs virus. Viruses containing wild-type segments (A), Ms (B), NSs (C), and both Ms and NSs (D) are indicated. Black boxes at the end of each viral segment, viral 3′ and 5′ noncoding regions; white boxes, PR8 viral products from the NS (NS1 and NEP) and M (M1 and M2) segments; light gray boxes, the region until the splicing donor in both viral segments (NS and M); dark gray boxes, sequence of the PTV-1 2A autoproteolytic cleavage site. In the virus illustrations, the WT and split NS and M viral segments are indicated with gray and black lines, respectively.