The Usefulness of Human Lung Embryonal Fibroblast Cells (MRC-5) for Isolation of Enteroviruses and Adenoviruses

Although various cell lines have been used for virus isolation, few study of virus isolation using MRC-5 cell, a human embryonic lung fibroblasts, have been reported in Japan. MRC-5 and other cell lines (Caco-2, Vero, RD-18s, LLC-MK2, HeLa, MDCK, FL, B95a and HMV-II), and suckling mouse were compared for isolation of viruses from clinical specimens. A total of 3, 284 specimens, collected from clinics and hospitals in Saitama Prefecture between July 1997 and August 2001, were inoculated in these cells. A total of 1, 252 viral strains were isolated and 1, 190 viral strains of these were identified. MRC-5 detected 209 of specimens positive for various viruses. As for adenovirus, a total of 132 viral strains were isolated using cell lines described above, and 100 of 132 viral strains were isolated in MRC-5. MRC-5 showed the highest sensitivity for isolation of adenovirus 3 and 7 (79.1% and 100%) of all other cells. The sensitivity in isolation of these viruses in HeLa was 58.1% and 50.0%, respectively. It showed that MRC-5 is able to isolate enterovirus, especially coxsackie virus A 16 and enetrovirus 71 with a high sensitivity (85.7% and 73.7%). RD-18s detected 35.7% and 26.3% of coxsackie virus A16 and enterovirus 71 isolates, LLC-MK2 detected 60.7% and 47.4%, and Vero detected 48.6% and 52.6%, respectively. Coxsackie virus B group was not isolated, except for a few coxsackie virus B5 strains. Enteroviruses except coxsackie virus A 16 and enterovirus 71 were isolated more frequently in Caco-2 and RD-18s. Seven hundred thirteen strains of influenza viruses were isolated in MDCK and Caco-2, but none was isolated in MRC-5. It was probably due to the maintenance medium without trypsin. The isolation rate of herpes simplex virus in Vero was 88.9% and MRC-5 showed 77.8%, it was high secondary to Vero by MRC-5. However, the CPE was detected in a few days in MRC-5, it was earlier than in Vero. The MRC-5 is possible to be maintained without changing the maintenance medium and passaged for 2 weeks, and clear CPE was observed. On the other hand, the disadvantages in using the MRC-5 were that the passage was limited and that the split ratio was only 1: 2. However, the MRC-5 was used successfully for virus isolation, especially coxsackie virus A16, enterovirus 71 and adenoviruses, from clinical specimens.