FIG. 4.

(A) Heparin-Sepharose chromatography of E^rns and E2. In a separate experiment, purified E^rns or E2 was loaded on the column at a concentration of 0 mM NaCl. Proteins were eluted with a stepwise NaCl gradient (0 to 1,000 mM). The fractions were assayed for E^rns or E2 in an ELISA as described in Materials and Methods. The results of E^rns and E2 are presented in a single graph. The NaCl concentration is shown for the E^rns fractions. The concentration NaCl of the E2 fractions did not differ significantly from the concentration of the corresponding E^rns fractions. (B) Heparin-Sepharose chromatography of CSFV strain Brescia C1.1.1. Cell-free, partially purified virus was loaded on the column at a concentration of 100 mM NaCl and eluted with a stepwise NaCl gradient of 100 to 1,000 mM. Fractions were assayed for virus in a plaque assay as described in Materials and Methods. The NaCl concentration of fractions was determined by measuring the osmolarity.