REPLICATION OF HELICOVERPA-ZEA NUCLEAR POLYHEDROSIS-VIRUS IN HOMOLOGOUS CELL-LINES GROWN IN SERUM-FREE MEDIA

A parental cell line, BCIRL-HZ-AM1 (HZAM1) derived from Helicoverpa ze a (Boddie) (Lepidoptera:Noctuidae) pupae and one of its clones BCIRL-H Z-AM1-B3 (HZ1B3), were grown as attached cells in two commercial insec t serum-free media, EX-CELL 400 and SF-900, and one modified vertebrat e serum-free medium, MCM1. A serum-containing medium, TC199-MK, in whi ch the cell lines were normally propagated, was used as control. Cell doubling times for HZAM1 in EX-CELL 400, SF-900, and TC199-MK, were 27 , 28, and 30 hr, respectively; in contrast, there was negligible growt h in MCM1. The shortest cell doubling time for HZ1B3 in serum-free med ium was 25 hr, as observed in EX-CELL 400. Other cell doubling times w ere: 35 hr in TC199-MK, 38 hr in MCM1, and 45 hr in SF-900. Total extr acellular virus production of H. zea nuclear polyhedrosis virus (HzSNP V)-infected HZAM1 cells was similar in all media (3.0-6.3 x 10(5) PFU/ ml). Extracellular virus titers for HZ1B3 in EX-CELL 400 and SF-900 we re similar (3-4 x 10(5) PFU/ml) but less than those produced in HZAM1. For HZ1B3, the lowest extracellular virus titer was recorded in MCM1 (0.8 x 10(5) PFU/ml) and the highest in TC199-MK (12 x 10(5) PFU/ml), Production of HzSNPV occlusion bodies (OB) by HZAM1 cells differed sli ghtly between the media (2.9-6.2 x 10(7) OB/ml). For HZ1B3 cells, OB p roduction was similar in TC199-MK, EX-CELL 400, and SF-900 (3.6-6.0 x 10(7) OB/ml), but considerably lower in MCM1 (1.0 x 10(7) OB/ml), Occl usion bodies from both infected cell lines grown in serum-free media a nd in TC199-MK were equally infectious for H. zea larvae. (C) 1995 Aca demic Press, Inc.