FIG. 2.

Infectivity of HMPV in various cell lines as analyzed by using EGFP-expressing HMPV. (A) The full-length genome cDNA of the HMPV JPS02-76 strain flanked by the T7 promoter (T7) and hepatitis delta virus ribozyme (Rz) sequence was cloned into pBluescript vector (Stratagene). An additional transcription unit for EGFP was created between the N and P genes. Restriction enzyme recognitions sites for Tth111I and SacI were used for cloning. GE, gene end sequence; GS, gene start sequence; Le, leader sequence; Tr, trailer sequence. (B) Infectivity titers of rJPS02-76EGFP were determined in various cell lines. Cell lines were infected with the same stock of rJPS02-76EGFP and incubated in appropriate culture media in the absence of trypsin. At 30 h p.i., EGFP-expressing cell numbers (cell infectious units) were counted. The number determined in LLC-MK2 cells was set to 100%. LLC-MK2, Vero, Vero C1008, and CV-1 cells are monkey kidney-derived cell lines. HEK293 cells are a human kidney-derived cell line. H157, H322, H358, H1299, H460, A549, EBC-1, and Calu-3 cells are human lung carcinoma cell lines. HeLa cells are a human cervical adenocarcinoma cell line. L929 cells are a mouse fibroblast line. B95a cells are a marmoset B-lymphoblastoid cell line. CHO cells are a hamster ovary-derived cell line.