FIG. 7.

Successful replacement of both the IHNV M and G genes by their VHSV counterparts. After four passages, viral genomic RNA extracted from supernatants of cells infected with either wild-type IHNV or rIHNV-M-Gvhsv was amplified by RT-PCR with specific M or G primers derived from IHNV or VHSV sequences. PCR products were analyzed on a 1% agarose gel with (+) or without (−) restriction enzyme digestion. A control without reverse transcriptase (−RT) was added to ensure that no contaminating plasmids were present in the rIHNV-M-Gvhsv-infected cell supernatant. The sizes of the fragments (in nucleotides) are given on the left for the IHNV M and G genes and on the right for the VHSV M and G genes.