TABLE 1.
Passage of chimeric virusa
| Passage no. | Yield (PFU/ml) | Amino acid changes inb:
|
|
|---|---|---|---|
| SIN E2 | RR E1 | ||
| 0 | 1 × 104 | ||
| 5 | 3 × 105 | Asp-248→Tyr | None |
| 10 | 2 × 106 | Asp-248→Tyr | Gln-411→Leu |
a
Passage series 1. P0 was initiated by infection of BHK cells with a single plaque, and the yield is that after 72 h. For P1 to P10, the culture fluid from the preceding passage was diluted fivefold and used to infect a new plate of cells, and the yield is that after 48 h of infection.
b
The entire region encoding structural proteins in virus present in P5 and P10 virus was cloned and sequenced, and the sequence was compared with that in the chimeric cDNA clone pSIN(RRE1).