THE CULTIVATION OF DENGUE-1 (HAWAIIAN) VIRUS IN TISSUE CULTURE

Abstract

A carrier culture of dengue-1 virus in human skin cell (strain HuS 2806) was established and maintained for 15 months without any obvious change in character of the cell or the virus. Virus was consistently recovered from culture fluid. Titers varied from 10 to 100,000 mouse LD50 per .03 ml but tended to increase in later months. An unexplained feature of the culture was the reappearance of titratable virus in culture fluid within 30 minutes after repeated washing and fluid changes of infected cells. Substitution of ox serum ultrafiltrate for the horse serum component of the growth medium resulted in morphologic changes suggestive of cytopathogenicity but these changes could not be correlated with significant virus release. Treatment of the culture with fluorescent antibody (indirect method) resulted in specific fluorescent foci within the cytoplasm of at least 10% of the cells, indicating that this proportion of cells contained viral antigen. The carrier culture virus was compared with the original dengue-1 strain by using the serum neutralization test in mice. Rabbit antisera neutralized the carrier culture virus as well as the homologous virus (with neutralization indexes in excess of 100 mouse LD50).